Enhancing the Magnetization, Dielectric Loss and Photocatalytic Activity of Co-cu Ferrite Nanoparticles Via the Substitution of Rare Earth Ions

Enhancing the Magnetization, Dielectric Loss and Photocatalytic Activity of Co-cu Ferrite Nanoparticles Via the Substitution of Rare Earth Ions | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Enhancing the Magnetization, Dielectric Loss and Photocatalytic Activity of Co-cu Ferrite Nanoparticles Via the Substitution of Rare Earth Ions M.A. Abdo, S.F. Mansour, Faten Al-Hazmi, M.S. AlHammad, M.S. Sadeq This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-770192/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract This study reports the impact of lanthanum substituted Co-Cu ferrite nanoparticles on the RhB dye disposal. Moreover, a complete investigation for the structural, magnetic and optical properties for Co 0.5 Cu 0.5 La x Fe 2-x O 4 (CCL) nanoferrites was executed. These nanocrystals synthesized via a combustion approach with a peculiar lattice parameter behavior; which discussed through three hypotheses. STEM-EDX micrographs of some selective samples confirm the nanocrystalline nature with presence of all constituents’ chemical elements CCL nanoferrites. The saturation magnetization of CCL nanoferrites was tuned with La 3+ ions substitution. Contrary to the expected results, anisotropy constant introduced a decrement behavior with La/Fe substitution process. The microwave frequency (ω M ) values for all CCL nanoparticles are in the range 11.87 GHz–9.46 GHz. The band gap has a peculiar behavior; a red shift and followed by a blue one. Through photodegradation testing, we explicate the RhB degradation mechanisms over our CCL nanoferrites. The nanoferrite Co 0.5 Cu 0.5 La 0.15 Fe 1.85 O 4 has a moderate saturation magnetization, highest coercivity, and lowest loss which is a suitable candidate for data recording applications, furthermore can be utilized as a photocatalyst for RhB effluents removal with degradation efficiency 94.50% at 180 min solar radiation. Ceramics CCL RhB nanocrystals synthesized STEM-EDX anisotropy Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 1. Introduction In day-to-day life environmental pollution from organic dyes became an intractable problem. Particularly, rhodamine B (RhB) organic dye can be vastly utilized in diverse purposes. Physically, RhB is bright-red in color with molecular formula C 28 H 31 ClN 2 O 3 , molecular weight 479 g/mol and water solubility (8–15 g/L at 20°C). In fact, RhB can cause reliable environmental problems, besides its capability to make skin or eyes irritation [ 1 ]. All these factors motivate us to generate effectual and cost-effective removal technique to overcome this environmental threat. Photocatalytic degradation of dyes using spinel ferrite nanoparticles is a salutary and environmentally friendly approach for dyes removal [ 2 ]. Recently, researches focus in the field of utilizing spinel ferrites as catalysis due to its moderately narrower band gap (~ 2.0 eV), where can absorb both Vis. and UV radiations [ 3 ]. Moreover, the magnetic nature of spinel ferrites empowering its easy separation and retrieval of the ferrite powder again [ 4 ]. Kefeni et al., [ 5 ] declared that cobalt and copper ferrites (CoFe 2 O 4 & CuFe 2 O 4 ) besides their corresponding composites introduce higher photocatalytic performances. Consequently, we got excited to exploit a new nanoferrite containing both cobalt and copper cations (Co 0.5 Cu 0.5 Fe 2 O 4 ) which doping with a rare earth element to augment their overall photocatalytic performance. Rather than their catalytic performances, Co 0.5 Cu 0.5 Fe 2 O 4 , also, acquire amazing properties among the reminder ferrite types [ 6 ]. Indeed, CoFe 2 O 4 is a promising material for diverse implementations based on its highest magneto-crystalline anisotropy (~ 3×10 5 J.m − 3 ) [ 7 ]. This property make CoFe 2 O 4 has a feature suitable for storage devices applications. Basically, the crucial necessity for these magnetic materials utilizing in storage data that it should been have moderate saturation magnetization and high coercivity (H C ), which are satisfied in CoFe 2 O 4 nanoparticles [ 8 ]. Additionally, CuFe 2 O 4 nanoparticles with the Jahn-Teller ion (Cu 2+ ) have ubiquitous applications; based on their magneto-strictive property for the ferrite material [ 9 ]. Hence, in this investigation, by choosing Co 0.5 Cu 0.5 Fe 2 O 4 nanoferrite to be the pristine sample we can obtain the two features producing high H C ; higher magneto-crystalline anisotropy (by CoFe 2 O 4 ) besides higher magneto-strictive property (by CuFe 2 O 4 ). Generally, Rare earth elements have auspicious effect on enhancement diverse nanoferrite systems [ 10 – 12 ]. Our research group, in the previous publication, declared that the substitution of lanthanum (La), as a rare earth element, into Zn-Mg ferrite system enhanced its physical properties besides improving its degradation efficiency [ 13 ]. So, we are enthused to use La ion to enhance the features of another nanoferrites system as Co 0.5 Cu 0.5 La x Fe 2−x O 4 . Thus, by adding La 3+ ions, it is expected to obtain the following results; (1) moderate value of magnetization, where La 3+ ions have lower magnetic moment than Fe 3+ ions; (2) high value of coercivity, where La 3+ ions will generate spin-orbit coupling between 4f and 3d levels; (3) diminishing the energy gap, by energy levels creation by lanthanum electrons inside band gap, and interns enhance the photocatalytic property. In view of hopeful properties of spinel ferrite nanoparticles, current research investigates structural, magnetoelectric, optical features besides photocatalytic activity of Co 0.5 Cu 0.5 La x Fe 2−x O 4 nanoparticles; which is not investigated until now. 2. Materials And Methods Pure and La 3+ subrogated Co 0.5 Cu 0.5 Fe 2 O 4 nanoferrites were prepared through citrate combustion technique. In this approach metals nitrate; cobalt, copper, iron, lanthanum, with definite amounts, in addition to citric acid and ammonia solution were used. The combustion process of Co 0.5 Cu 0.5 La x Fe 2−x O 4 (CCL); (0 ≤ x ≤ 0.15; step 0.03) ferrite nanoparticles are reported minutely in an earlier publication [ 14 ]. The yield CCL nanoferrites were investigated by XRD, FTIR, STEM-EDX besides its sundry features; dielectric, magnetic, optical and photocatalytic activity using the identical instruments in previous works [ 13 , 15 ]. 3. Results And Discussion 3.1. Structural and morphologic investigations 3.1.1. XRD analysis Figure 1 manifests the XRD diffractograms of Co 0.5 Cu 0.5 La x Fe 2−x O 4 (CCL); (0 ≤ x ≤ 0.15) ferrite nanoparticles. The chart of pristine Co 0.5 Cu 0.5 Fe 2 O 4 nanoferrite sample (x = 0.0) gives peaks at diffraction angles 2θ = 18.3, 30.26, 35.65, 37.20, 43.30, 53.60, 57.20, 62.80 and 74.24 that indexed to Miller notations as; 111, 220, 311, 222, 400, 422, 511, 440 and 533 in that order. Actually, these diffraction peaks are totally indexed to the FCC spinel lattice conforming to JCPDS cards (00-001-1121 and 01-077-0010). Also, the XRD of the reminder Co 0.5 Cu 0.5 La x Fe 2−x O 4 ferrite nanoparticles have diffraction peaks congruous to those observed in the pristine sample with slightly shift for diffraction angles; which confirm the spinel structure for all CCL nanoferrites. The substitution of La 3+ not produces any impurities, or foreign phase; confirming the wholly dissolution of La 3+ ions in CCL spinel lattice. Furthermore, the peaks are sharp and spread over the XRD patterns; affirming the nanocrystalline nature for all the investigated CCL nanoferrites. The lattice parameter (a exp ) for all Co 0.5 Cu 0.5 La x Fe 2−x O 4 nanoparticles is calculated using the related Eq. in [ 16 ]. Although the substitution process is a larger ion, La 3+ (1.032 Å), instead of a smaller one, Fe 3+ (0.645 Å) [ 17 ], the lattice parameter did not introduce an increment behavior. It has a peculiar trend; decrement from (8.375Å at x = 0.0) - (8.327Å at x = 0.12) and augment for the nanoferrite with x = 0.15 to 8.375Å, see Fig. 2. Three hypotheses are further suggested to interpret this enigma; two for the decrement behavior and one for the increment situation. Firstly, microstrains are the reason for the a exp decrement behavior, where make a compensation role against the large predictable crystal expansion. In fact, La 3+ ions (with its large radius) tend to enlarge the a exp values, then as a reparations for this alteration in spinel lattice, strain attempts to reduce it [ 18 , 19 ]. Mariosi et al. [ 20 ], reported alike behavior for decreasing lattice parameter of CoLa x Fe 2−x O 4 ferrite nanoparticles and explicated its behavior using the same reason. Secondly, bond dissociation energy (BDE) is another factor for interpreting this decrement behavior. In fact, BDE of (La–O) is (619 kJ/mol) which be larger than that of (Fe–O) (409 kJ/mol) [ 21 ]. Consequently, the La–O bond is shortened and sturdy; therefore, CCL lattice volume and consequently its parameter are decreased. As for the third hypothesis, it will be for the nanoferrite with x = 0.15; where its a exp increment behavior can be interpreted in view of cations redistribution between tetrahedral (A) and octahedral (B) positions in CCL ferrite lattice. Actually, the ionic radii at A-sites are r A (Co 2+ ‏) = 0.58 Å, r A (Cu 2+ ‏) = 0.57 Å, r A (Fe 3+ ‏) = 0.49 Å, and at B-sites are r B (Co 2+ ‏) = 0.745 Å, r B (Cu 2+ ‏) = 0.73 Å, r B (Fe 3+ ‏) = 0.645 Å, r B (La 3+ ‏) = 1.032 Å [ 17 ]. Then, the larger La cations will situate in B-site at expense of Fe 3+ ones, which forced some Fe 3+ cations to emigrate from B- to A-sites and consequently some Co 2+ and Cu 2+ , with their larger radii in B sites rather than in A-sites, will transfer from A- to B-sites; producing a exp increment behavior for the nanoferrite with (x = 0.15). Ounacer et al. [ 22 ], declared a similar attitude and expound its result with the same reasoning. Although, crystallite size can be determined by diverse methods; Rietvled, Williamson-Hall (W-H) or Scherrer’s formula, W-H method is the most convenient one, because the strain components are involved. Consequently, the crystallite size (D W−H ) besides lattice strain (ε s ) of CCL ferrite nanoparticles is determined using Williamson-Hall method. Figure 3(a-f) shows the W-H graphs for all CCL nanoferrites, concerning the obtained diffraction peaks, with their better linear fitting; for determining crystallite size from intercept and lattice strain from the slope. Then crystallite size of CCL nanoferrites introduces distinctive trend; increment from 20.94 nm (at x = 0.0) to 33.01 nm (at x = 0.09) and then decrease step forward for x = 0.12 and 0.15 to 30.27nm and 28.41 nm, respectively; see Fig. 2. This means that for small La 3+ content, up to the nanoferrite with x = 0.09, the rates of nucleation and growth steps increase producing large size for crystallites [ 23 ]. Therefore, the high concentrations of La 3+ ions (x = 0.12 and 0.15) resort at grain boundaries, producing grain boundaries pinning, and interns shackle grain growth; resulting decreasing crystallite size trend for these two nanoferrite samples. On the other hand, lattice strains of CCL nanoferrites have positive values, see Fig. 2; demonstrating that all CCL nanoferrites possessing tensile strain with increasing values up to x = 0.09 and then decrease for further La 3+ substitution. This increment behavior of lattice strain confirms the first hypothesis for lattice parameter decrement; as discussed above. 3.1.2. Morphological characterization The STEM-EDX of some selective samples, Co 0.5 Cu 0.5 Fe 2 O 4 , Co 0.5 Cu 0.5 La 0.09 Fe 1.91 O 4 and Co 0.5 Cu 0.5 La 0.15 Fe 1.85 O 4 as manifested in Fig. 4(a-f). The STEM graphs, Fig. 4(a, c and e), demonstrate the nanocrystalline nature of all the samples. It is plainly noticed the STEM micrographs possess almost spherical crystallites which indiscriminately distributed throughout the ferrite sample surface. Furthermore, CCL samples show agglomeration partly, which emanates from its constituents magnetic nature in addition to binding forces among surface nanoparticles. To corroborate the existence of the different metals in CCL ferrite samples, EDX micrographs were utilized to this mission as seen in Fig. 4(b, d and f). Actually, the EDX charts of CCL powders affirmed existence of metal cations; La, Co, Fe, Cu and O ions with no others traces of impurity; asserting the purity of CCL nanoferrite samples even substituted by a rare earth element (La). Furthermore La/Fe atomic percent matches with the desired ratios; affirmed from La peaks leveraging on account of iron; as in Fig. 4(d,f). Additionally, atomic% ratio of (Co + Cu)/Fe and (Co + Cu)/ (Fe + La) is just about 0.5; corroborating, once more, the prepared powders purity. Furthermore, the characteristic mapping of Co 0.5 Cu 0.5 La 0.15 Fe 1.85 O 4 nanoferrite, for instance, Fig. 5, which reveals the constituent elements homogeneous distribution. 3.2. Magnetic properties 3.2.1. Magnetic parameters of CCL nanoferrites The hysteresis loops for the Co 0.5 Cu 0.5 La x Fe 2−x O 4 nanoferrites at room temperature (RT = 303K), utilizing a field to ± 20 kOe, are illustrated in Fig. 6. Then collected magnetic parameters; M S , M r and H C of CCL nanoferrites are tabulated in Table 1 . The M S values are steadily diminishing with further substitution of La 3+ ion; from M S = 53.67 emug − 1 (for x = 0.0) until M S = 42.75 emug − 1 (for x = 0.15). In fact, M S values of ferrite materials are in straight proportionality with cations magnetic moment, which relies mainly on the unpaired (e) in the ferrite cations [ 24 ]. Hence, this progressively decrement in M S values is a logical result to the magnetic moment difference for La/Fe cations, where La (2.78 µ B ) and Fe (5.92 µ B ); resulting deteriorating A-B super-exchange type [ 25 ]. Then remanent magnetizations of CCL nanoferrites introduce the identical trend as saturation magnetization, with the same dialectics, from 27.79 to 21.53 emug − 1 ; with further La substitution. Table 1 The lattice parameter (a exp ), crystallite size (D W−H ), saturation magnetization (M s ), remanent magnetization (M r ) and coercivity (H C ) initial permeability (𝜇 i ), anisotropy constant (K) and microwave frequency (ω M ) of CCL nanoferrites. x a exp (Å) D W−H (nm) M S (emu/g) M r (emu/g) H C (Oe) 𝜇 i K (erg/cm 3 ) ω M (GHz) 0.0 8.375 20.94 53.67 27.79 1078.80 1.00 60311.66 11.87 0.03 8.375 21.56 51.53 25.95 1044.40 1.02 56060.35 11.40 0.06 8.330 25.58 51.07 26.03 957.73 1.31 50949.24 11.30 0.09 8.330 33.01 50.57 25.46 922.19 1.74 48578.28 11.19 0.12 8.327 30.27 43.86 22.03 1048.60 1.22 47907.91 9.70 0.15 8.375 28.41 42.75 21.53 1111.30 1.05 49487.58 9.46 Table 2 The kinetic rate constants (k 0 , k 1 and k 2 ) and correlation coefficient (R 2 ) for zeroth, first and second order reaction kinetics of RhB dye with and without CCL photocatalyst nanoparticles. Sample Kinetic model parameters Zeroth order First order Second order RhB k 0 =-1.23×10 − 4 R 2 = 0.977 k 1 = 1.76×10 − 4 R 2 = 0.978 k 2 = 2.52×10 − 4 R 2 = 0.980 RhB + Co 0.5 Cu 0.5 Fe 2 O 4 k 0 = -9.11×10 − 4 R 2 = 0.998 k 1 = 0.00137 R 2 = 0.998 k 2 = 0.00207 R 2 = 0.994 RhB + Co 0.5 Cu 0.5 Sm 0.09 Fe 1.91 O 4 k 0 = -0.00459 R 2 = 0.995 k 1 = 0.01498 R 2 = 0.868 k 2 = 0.08797 R 2 = 0.587 For H C values, it possesses a distinct trend; firstly presents a downward one, from 1078.8 to 922.19 Oe (for 0.0 ≤ x ≤ 0.09), and an upward one from 922.19 to 1111.3 Oe (for 0.09 ≤ x ≤ 0.15). This abnormal trend of H C for CCL nanoferrites can be argued as follow. Firstly, the introduction of the nonmagnetic La 3+ ions in CCL nanoferrites and its accompanied impact is diminishing saturation magnetization; therefore, the field needed to clobber this magnetization property to 0 levels, also, is decreased. Secondly the H C behavior in the range 0.09 ≤ x ≤ 0.15 has two reasoning. The first one is the CCL crystallite size impact; with its inversely proportional to coercivity [ 26 ]. As shown in Fig. 2, crystallite size of CCL nanoferrites in the span 0.09 ≤ x ≤ 0.15, introduce a decrement behavior. Hence, as the crystallite size diminishes as the grain boundaries augment, i.e., the disordered regions increase and required coercivity field, H C , as a result increase. The second one is magneto-crystalline anisotropy of the substituted rare earth element (La) which increases the coercivity of the resultant ferrite. Actually, in materials containing heavy rare-earth elements, the spin–orbit coupling is strong. Once magnetized, a high field must be utilized to reverse the magnetization direction after conquer the anisotropy produced from this coupling [ 27 ]. Thus, with further La substitution, in the span 0.09 ≤ x ≤ 0.15, spin-orbit coupling and consequently the magneto-crystalline anisotropy of CCL nanoferrites increase and hence H C value increases. At last, it is concluded that the CCL samples have hard magnetic features which can be adjusted by La 3+ ions substitutions. Finally, the nanoferrite Co 0.5 Cu 0.5 La 0.15 Fe 1.85 O 4 have a moderate saturation value 42.75 emu/g and the highest coercivity value 1111.3 Oe; candidate it to be an effective material for storage and recording applications. Additionally, initial permeability and anisotropy constant of the Co 0.5 Cu 0.5 La x Fe 2−x O 4 nanoferrites are calculated using the Ref. [ 28 , 29 ], and tabulated in Table 1 . $$Anisotropy constant \left(K\right)=\frac{{M}_{S}\times {H}_{C}}{0.96}$$ $$Initial permeability \left({\mu }_{i}\right)=\frac{{M}_{S}^{2}\times {D}_{W-H}}{K}$$ In fact, initial permeability has a distinctive attitude with La/Fe substitution process; increasing behavior for the nanoferrites with 0.00 ≤ x ≤ 0.09 and a decreasing one for x = 0.12 and 0.15 nanoferrites. Although, saturation magnetization has a regular decrement behavior, \({\mu }_{i}\) introduces this abnormal demeanor. Indeed the impact of crystallite size and anisotropy constant are decision makers for \({\mu }_{i}\) behavior. Thus La substitution in Co-Cu nanoferrites, in the range 0.00 ≤ x ≤ 0.09, supports magnetic flux to pass and concentrate within these nanoferrites and inhibit it for x = 0.12 and 0.15 nanoferrites. Contrary to expected results anisotropy constant introduces a decrement behavior with La/Fe substitution process. Where, it was expected that the spin-orbital coupling of La ions can enhance anisotropy property of these nanoferrites. 3.2.2. High frequency response of CCL ferrite nanoparticles Basically, ferrite materials are the only ones available for microwave realm applications. Where for frequency (1 GHz ≤ f ≤ 1000 GHz), the electrical energy is not transported via wires, but through electromagnetic waves which contained in wave-guides and transmitted through space. So we have to investigate the high frequency response of the prepared CCL nanoferrites to discover their applications in microwave fields. The microwave frequency (ω M ) values for all CCL nanoparticles are determined using Ref. [ 30 ] and then saved in Table 1 . From the calculated ω M values, 11.87 GHz–9.46 GHz, CCL nanoferrites may be employing in high frequency applications. These values introduce a significant progress compared with other systems containing different rare earth elements with maximum ω M value 8.4 GHz [ 31 ]. 3.2.3. Switching field distributions (SFD) response of CCL ferrite nanoparticles Figure 7, with its inset curve, shows the SFD plots (dM/dH vs. H) of all CCL nanoferrites. Physically, SFD plots scout the constituting cations exchange coupling. All SFD curves acquire higher values at large reverse field meanwhile introduce an almost constant one for higher fields; affirming the vigorous cations exchanges at higher reverse filed. Then inset plot, for large reverse field; confirming those figures are discontinuous. Analogous behavior was declared regarding different ferrites containing diverse rare earth elements [ 31 ]. 3.3. Dielectric properties Regarding to dielectric bounds of La- substituted Co-Cu ferrite nanoparticles, special studies have been investigated. Actually, in frequency span (50Hz-5MHz at RT), dielectric parameters (dielectric constant, ε′, and loss tangent, tanδ) besides conductivity (σ ac ) for the synthesized system of Co 0.5 Cu 0.5 La x Fe 2−x O 4 nanoparticles have been studied. Fundamentally, ε′ refers to the amount of stored energy in the ferrite material, whereas tanδ gives the energy loss out of phase rather than the response of the material, whilst σ ac , determines the kind and mechanization of conduction within an applied field. Actually, the ε′ and σ ac results of Co 0.5 Cu 0.5 La x Fe 2−x O 4 samples are determined using the Ref. [ 32 ], whilst tanδ result is getting directly from the instrument. As noticed in Fig. 8(a) ε′ decreases more speedily in the frequency then becomes dormant as frequency augment; which is the typical demeanor of all ferrite [ 33 ]. Based on Koop's model, any ferrite structure formed by arrangement of conducting regions (grains) estranged with lower conducting regions (grain boundaries) [ 34 ]. Hence at lower frEq. region various charge carriers transfer among dissimilar ions of the same element, e.g., Fe 2+ &Fe 3+ , which accumulate on grain boundaries (GBs); due to it high resistivity. This phenomenon is called Maxwell-Wagner (M-W) polarization which gives a high value of dielectric constant which decreases slowly with frequency [ 35 ]. At higher frEq. these charges within grains itself cannot pursue the frequency of the applicable field, and then polarization diminishing and almost stable ε′ level is obtained [ 36 ]. As observed from inset curve of Fig. 8(a), the dielectric constant of CCL nanoferrites decrease gradually with further La 3+ substitution in view of two respects. The first one is the electron hopping among Fe 2+ &Fe 3+ ions reduces by La 3+ /Fe 3+ ions replacement. The second is account for the increment of resistivity, originated from 3d-4f coupling of La ions, where the relation between resistivity and ε′ is inversely proportion [ 37 ]. As for the σ ac behavior, it has a growing attitude with frequency; see Fig. 8(b). Many workers declared that presence similarity for σ ac and ε′ mechanisms for ferrite materials [ 38 – 40 ]. Consequently, the preceding interpretation of ε' for CCL nanoferrites is benefit for understanding σ ac behavior with frequency. Hence, as noticed from the inset curve of Fig. 8(b), σ ac decreases with the augment in La content. As for conductivity frequency dependence, the crowd of charges on CCL nanoferrites GBs is the major cause for the independent regime in σ ac plot. By increasing frequency, the impact of interior Gs of CCL nanoferrites and charge carriers transfer are accountable for σ ac increment demeanor. Generally, frequency acts to augment the conduction phenomenon by its propelling diverse charge carriers between the conduction positions [ 41 ]. The tanδ of the investigated CCL ferrite nanoparticles is given in Fig. 8(c). In fact, the decreases in tanδ value are noticed with further increasing frequency and with La 3+ ions substitution; see the inset curve of Fig. 8(c). This behavior of tanδ can be justified using two facts. With increasing La content in CCL nanoferrites, polarization (ε′) depressed and also the accompanied loss decrease; this is the first reason. The other cause for tanδ behavior is the CCL crystallite size by it's inversely proportion with it [ 42 ]. 3.4. Optical studies 3.4.1. UV-Visible absorption and optical energy gap For the present Co 0.5 Cu 0.5 La x Fe 2−x O 4 ; (x = 0.0, 0.03, 0.06, 0.09, 0.12, 0.15) ferrite nanoparticles, one can notice a broad absorption band positioned nearly at 500 nm; as shown in Fig. 9. Generally, ferrite materials are opaque at wavelengths ≤ 200 nm; at which the photon energy is ≥ optical band gap (E g ), which is required for transition from valence to conduction bands [ 43 ]. The E g values of Co 0.5 Cu 0.5 La x Fe 2−x O 4 nanoferrites can be calculated by extrapolating the linear portion curve of (αhν) 2 vs. photon energy (hν) to (αhν) 2 = 0; for direct allowed transition (Tauc's plot) (Fig. 10(a-f)) [ 44 ]. From Tauc's plot, E g values of CCL nanoferrites are determined. Basically, the band gap can be tuned based on several factors: e.g., crystallite size, structural parameter and impurities. The calculated E g values of CCL nanoferrites are displayed in Fig. 11. In fact our energy gap possesses a peculiar demeanor; a red shift from 3.04 eV to 2.46 eV (for 0.0 ≤ x ≤ 0.09) and a blue shift from 2.46 eV to 2.98 eV for (0.09 ≤ x ≤ 0.15). A similar E g behavior was observed in an earlier work for Zn-Mg nanoferrites [ 13 ]. This behavior of E g can be explained trough two scenarios. Firstly, further La content generates a lot of donor levels in the forbidden band, producing E g decrement. Secondly, this tendency of E g may be accredited to the decrement attitude of CCL nanoferrites crystallite size in the range 0.09 ≤ x ≤ 0.15 (see Fig. 2); where the relationship between the band gap and particle size is an inversely one [ 15 ]. Also the augmentation of conductivity of Co-Cu nanoferrites with further La 3+ substituting confirms the E g behavior in that range. 3.4.2. Photocatalytic activity The influence of Co 0.5 Cu 0.5 La x Fe 2−x O 4 nanoferrites on photo-catalytic dye degradation of Rhodamine B (RhB) was investigated using absorption spectra. However, the E g of photocatalyst governs the absorbed wavelength and produces electron-hole pairs. The nanoferrite specimens with x = 0.0 and 0.09 La 3+ were chosen for this investigation because x = 0.0 represent the pristine ferrite and x = 0.09 has the least E g value. This choice based on the opposite relation between E g and photodegradation behavior [ 13 ]. Moreover, the replacement of rare earth cations in Co-Cu ferrite gives good optical absorption in visible range point toward enhanced photodegradation efficiency. As a consequence of metastable La-4f energy levels creation near the lower edge of the conduction band of Co-Cu ferrite, this indicates the decrease in the band gap. A further factor is the defects resulting from La doping which act as trapping centers and simplify the split-up of photogenerated electron-hole pairs and increase the life time of charge carrier [ 45 ]. The photo-catalytic degradation efficiency is obtained from the variation in Absorbance for the reason of direct relation between concentration (c) and absorbance (A) [ 46 ]. It is well known that, the self-degradation efficiency of RhB (without catalyst) is very small value for dye disposal [ 13 ]. Figure 12(a-c) manifests photocatalytic degradation of RhB and RhB + Co 0.5 Cu 0.5 La x Fe 2−x O 4 (x = 0.0, and 0.09) irradiated under solar light at variable times (from 0-180 min). The reduction in absorbance intensity designates enhancement in dye degradation. The mechanism for RhB photodegradation of the nanoferrite in which x = 0.9 La (as an example) is understood with aid of some of free radicals. All the spectra evident the characteristic absorption curves of RhB with a peak, at ~ 552 nm and a shoulder at ~ 512 nm [ 47 ]. The % degradation of samples is determined via the equation listed in Ref. [ 48 ]. Figure 13 illustrates % degradation for pure RhB and RhB over CCL nanoferrites with (x = 0.0 and 0.09). The % degradation, after irradiation for 180 min, of pure RhB dye is just 3.31%; which is an unsatisfactory impact. As for the % degradation for RhB over CCL nanoferrites with (x = 0.0 and 0.09) photocatalysts is enlarged; (22.37% and 94.50%, respectively). Hence, the catalytic recital was enhanced with La/Fe substitution process via the next most probable discussion. When the electrons were excited from valence band (VB) to created energy level CCL conduction band (CB) in the sample under sunlight irradiation, the photogenerated holes in VB react with surface water or hydroxyl ion to yield \({\text{O}\text{H}}^{\bullet }\) radical, which is a good oxidant in the degradation of RhB and instantaneously, electrons in the CB reacts with adsorbed oxygen molecule to yield \({\text{O}}_{2}^{.-}\) . Moreover, it combines with H + to yield \({\text{H}\text{O}}_{2}\) . [ 49 ], which react with trapped electrons to yield \({\text{O}\text{H}}^{\bullet }\) [ 50 ]. It is obvious that, \({\text{O}\text{H}}^{\bullet }\) , \({\text{H}\text{O}}_{2}\) ., \({\text{O}}_{2}^{.-}\) and \({h}_{VB}^{+}\) are active species included in RhB photodegredation. Regarding the previous argument, the photochemical reaction for the degradation of RhB under sunlight irradiation of Co-Cu-La ferrite photocatalyst was summarized as follows [ 13 ]. Co 0.5 Cu 0.5 La 0.09 Fe 1.91 -O 4 + hν \(\to\) Co 0.5 Cu 0.5 La 0.09 -Fe 1.91 O 4 + (e − and h + ) e − + \({O}_{2}\) \({\to O}_{2}^{.-}\) h + + \({HO}_{2}\) \(\to {H}^{+}\) + \({OH}^{\bullet }\) \({{O}_{2}^{.-}+H}^{+}{\to HO}_{2}\) ., 2e − \({+HO}_{2}\) . \(+\) \({H}^{+}{\to OH}^{\bullet }+{OH}^{-}\) and h + \({+ OH}^{-}\) . \({\to OH}^{\bullet }\) \({OH}^{\bullet }\) , \({HO}_{2}\) ., \({O}_{2}^{.-}\) , \({h}_{VB}^{+}\) +RhB \(\to Degraded products\) These radicals, formed from the previous steps, can interact with the toxic RhB dyes, converting its complex molecules to simple and non-toxic ones. Dhiman et al. [ 51 ] in previous work obtain comparable mechanisms for photocatalytic behaviors for CoFe 2 O 4 ferrite doped with various rare earths. To distinguish the photocatalytic activity protocol of CCL photocatalyst, the three kinetic models (0th, 1st and 2nd orders) are determined using the following equations [ 52 ]. \({A}_{t}={A}_{o}-{k}_{o}t\) , \({A}_{t}={A}_{o}{e}^{-{k}_{1}t}\) , \(\frac{1}{{A}_{t}}=\frac{1}{{A}_{o}}+{k}_{2}t\) where A t and A o are absorbance of RhB dye after and before irradiation time (t), respectively. For this mission, the plots of A t , ln(A o /A) and 1/A t versus time are determined with their linear fitting; see Fig. 14(a-c). The three kinetic constants (k 0 , k 1 and k 2 ) of zeroth, first and second order reaction kinetics, respectively of RhB and (RhB + CCL samples (x = 0.0 and 0.09) are calculated and tabulated in Table 2. Also, correlation coefficient (R 2 ) of each order kinetic is calculated and inserted in Table 2. The second order is the most favorable model for pure RhB, where its R 2 value is 0.980 (the highest value compared with other orders). As for RhB over CCL sample with (x = 0.0) has R 2 value 0.998 for both zeroth and first-orders; declaring that these models are favorable models for degradation. Meanwhile for RhB over CCL sample with (x = 0.09) has R 2 value 0.995 for zeroth; demonstrating this model is the most suitable model for degradation of this sample. Finally, the k 0 , k 1 and k 2 values for RhB dye degradations in presence of CCL nanoferrite powders are higher than those of pristine RhB dye; see Table 2. These outcomes confirm the CCL nanoferrites are capable of enhancing the RhB dye degradation efficiency in industrial community. Conclusion A sequence of lanthanum substituted cobalt-copper (Co 0.5 Cu 0.5 La x Fe 2-x O 4 ; 0x≤0.15) (CCL) were prepared via a combustion approach. XRD charts of CCL samples affirmed the spinel structure for the prepared powders. Although the substitution process is a larger ion, La 3+ (1.032 Å), instead of a smaller one, Fe 3+ (0.645 Å), the lattice parameter did not introduce an increment behavior. It has a peculiar trend; decrement from (8.375Å at x= 0.0) to (8.327Å at x= 0.12) then augment for the nanoferrite with x=0.15 to 8.375Å. The crystallite size of CCL nanoferrites introduces a distinctive trend; increment from (20.94 nm at x= 0.0) to (33.01 nm at x= 0.09) then decrease step forward for x=0.12 and 0.15 to 30.27nm and 28.41 nm, respectively. STEM micrographs possess almost spherical crystallites which indiscriminately distributed throughout the ferrite sample surface. M S values are steadily diminishing with further substitution of La 3+ ion; from M S = 53.67 emug -1 (for x= 0.0) to M S = 42.75 emug -1 at (x= 0.15). H C values, it possesses a distinct trend; firstly presents a downward one, from 1078.8 to 922.19 Oe (for 0.0≤x≤0.09), and an upward one from 922.19 to 1111.3 Oe (for 0.09≤x≤0.15). Dielectric constant and loss tangent have a decrement behavior with frequency and with substitution of La ions. E g has a peculiar demeanor; a red shift from 3.04 eV to 2.46 eV (for 0.0≤x≤0.09) and a blue shift from 2.46 eV to 2.98 eV for (0.09≤x≤0.15). The % degradation for RhB over CCL nanoferrites with (x=0.0 and 0.09) photocatalysts is enlarged; (22.37% and 94.50%, respectively). The nanoferrite Co 0.5 Cu 0.5 La 0.15 Fe 1.85 O 4 has a moderate saturation magnetization, highest coercivity and lowest loss which can be a suitable candidate for data storage applications. Moreover, Co 0.5 Cu 0.5 La 0.15 Fe 1.85 O 4 can be utilized as a photocatalyst for RhB effluents removal with degradation efficiency 94.50% at 180 min. Declarations Acknowledgements “This research work was funded by Institutional Fund Projects under grant no. (IFPHI-165-247-2020). 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-770192","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":43010474,"identity":"eb1083f3-2b49-4690-8d6e-c8458ddb82f2","order_by":0,"name":"M.A. Abdo","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA2ElEQVRIiWNgGAWjYDACCTA6wMBwvLHxAZhBvJYzhw8bkKjlRlqaBFFadGd3J95gqLkTzXcgx6yap+aOHD8D88NHN/BoMbtzdrMFw7FnuTMPnDG7zXPsmbFkA5uxcQ4+LTdyt0kwsB3O3XCwB6iF7XDihgM8bNKEtfwDajnMY1bM849YLYxtQC3H2NKYeduI07LZgrHvcO7MM8yHJef2HTaWbCbsl403GL4dzu27/7Dxw5tvh+X42ZsfPsanBQSY/0AZTDxgLgHlKIDxBymqR8EoGAWjYMQAAC68WolaIW8EAAAAAElFTkSuQmCC","orcid":"https://orcid.org/0000-0001-5883-0259","institution":"Zagazig University Faculty of Science","correspondingAuthor":true,"prefix":"","firstName":"M.A.","middleName":"","lastName":"Abdo","suffix":""},{"id":43010475,"identity":"afe34486-69f1-43f8-9476-908a9f9c7e6a","order_by":1,"name":"S.F. 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Sadeq","email":"","orcid":"","institution":"Sinai University","correspondingAuthor":false,"prefix":"","firstName":"M.S.","middleName":"","lastName":"Sadeq","suffix":""}],"badges":[],"createdAt":"2021-07-31 11:09:40","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-770192/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-770192/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":12153609,"identity":"206ae6c7-1f5b-418c-bcd9-846eb24b6682","added_by":"auto","created_at":"2021-08-05 16:32:11","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":14644,"visible":true,"origin":"","legend":"XRD difractograms of Co0.5Cu0.5LaxFe2-xO4; (0.0≤x≤0.15) nanoferrites.","description":"","filename":"Fig01.png","url":"https://assets-eu.researchsquare.com/files/rs-770192/v1/92c3baa1efb80dd5318beebb.png"},{"id":12153772,"identity":"f964c1f0-89d2-49b2-ba04-eb276ad10117","added_by":"auto","created_at":"2021-08-05 16:35:12","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":18290,"visible":true,"origin":"","legend":"Dependence of lattice constant (aexp), crystallite size (WD-H) and lattice strain of on La3+ content for CCL nanoferrites.","description":"","filename":"Fig02.png","url":"https://assets-eu.researchsquare.com/files/rs-770192/v1/b001221768b74bde47113593.png"},{"id":12153612,"identity":"7ddbdc38-ab91-4fd9-bd24-4c63ae40d446","added_by":"auto","created_at":"2021-08-05 16:32:12","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":30544,"visible":true,"origin":"","legend":"(a–f): W–H plot of Co0.5Cu0.5LaxFe2-xO4; (0.00≤x≤0.15) nanoferrites.","description":"","filename":"Fig03.png","url":"https://assets-eu.researchsquare.com/files/rs-770192/v1/6f0787879a9e0a746e670be4.png"},{"id":12154013,"identity":"06ee360f-6ab3-4b4c-9a97-798f0ce6c3a7","added_by":"auto","created_at":"2021-08-05 16:38:12","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":444505,"visible":true,"origin":"","legend":"(a-f): FE-SEM-EDX micrographs of (a) Co0.5Cu0.5Fe2O, (b) Co0.5Cu0.5La0.09Fe1.91O4 and (c) Co0.5Cu0.5La0.15Fe1.85O4 ferrite nanoparticles.","description":"","filename":"Fig04.png","url":"https://assets-eu.researchsquare.com/files/rs-770192/v1/625386adc5bcad697f9f402b.png"},{"id":12153778,"identity":"bc64b189-48b8-473f-9a45-8acbba8fff95","added_by":"auto","created_at":"2021-08-05 16:35:12","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":663760,"visible":true,"origin":"","legend":"Typical STEM-EDX mapping for Co0.5Cu0.5La0.15Fe1.85O4 ferrite nanoparticles. ","description":"","filename":"Fig05.png","url":"https://assets-eu.researchsquare.com/files/rs-770192/v1/96b54574c6794d88c6d98491.png"},{"id":12154014,"identity":"08691094-4537-4685-adfc-ebcb6d92e79b","added_by":"auto","created_at":"2021-08-05 16:38:12","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":11090,"visible":true,"origin":"","legend":"Hysteresis loops of CCL nanoferrites at RT.","description":"","filename":"Fig06.png","url":"https://assets-eu.researchsquare.com/files/rs-770192/v1/b406e09f5e1f7e00586c5a7c.png"},{"id":12154536,"identity":"ffe190ce-5988-4f60-a56d-a763af1bcbfb","added_by":"auto","created_at":"2021-08-05 16:44:12","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":58307,"visible":true,"origin":"","legend":"SFD response of CCL nanoferrites with its inset curve. ","description":"","filename":"Fig07.png","url":"https://assets-eu.researchsquare.com/files/rs-770192/v1/0ec22a576a6023d4e42c748e.png"},{"id":12153614,"identity":"22f7218c-c28d-43e1-a53d-d7af10fc34c0","added_by":"auto","created_at":"2021-08-05 16:32:12","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":42836,"visible":true,"origin":"","legend":"(a-c): The frequency dependence of (a) ε', (b) σac and (c) tanδ for CCL nanoferrites at RT. ","description":"","filename":"Fig08.png","url":"https://assets-eu.researchsquare.com/files/rs-770192/v1/9d4e417a5f007348f4de0f8a.png"},{"id":12153618,"identity":"487af9c1-4209-489c-98fb-ab0caabc4c42","added_by":"auto","created_at":"2021-08-05 16:32:12","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":14175,"visible":true,"origin":"","legend":"Optical absorption spectra as a function of wavelength for the prepared nanoferrite samples.","description":"","filename":"Fig09.png","url":"https://assets-eu.researchsquare.com/files/rs-770192/v1/7585cd93cd2492f215976f89.png"},{"id":12153610,"identity":"301602ca-09b5-4b76-8ff9-5199ccb0be4a","added_by":"auto","created_at":"2021-08-05 16:32:12","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":31946,"visible":true,"origin":"","legend":"(a-f): Tauc's plot for all CCL nanoferrites.","description":"","filename":"Fig10.png","url":"https://assets-eu.researchsquare.com/files/rs-770192/v1/e1f199d14554a0a8c901ad1c.png"},{"id":12153774,"identity":"1576da7f-21a5-4391-8856-61ae519835e3","added_by":"auto","created_at":"2021-08-05 16:35:12","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":10861,"visible":true,"origin":"","legend":"The change of Eg versus La3+ content.","description":"","filename":"Fig11.png","url":"https://assets-eu.researchsquare.com/files/rs-770192/v1/0703895a2ee648e55809a272.png"},{"id":12153620,"identity":"5659ade1-984e-40a3-aaa8-72fa74f118e4","added_by":"auto","created_at":"2021-08-05 16:32:12","extension":"png","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":264313,"visible":true,"origin":"","legend":"(a–c): Absorbance spectra of (a): pure RhB, (b): RhB with the Co0.5Cu0.5Fe2O4 nanoferrite and c): RhB with the Co0.5Cu0.5La0.09Fe1.91O4 nanoferrite; taken at different photocatalytic degradation times (0-180min).","description":"","filename":"Fig12.png","url":"https://assets-eu.researchsquare.com/files/rs-770192/v1/43b5a1a94da803711c1a4b3f.png"},{"id":12154328,"identity":"e7e2e3df-a688-45a8-8ed9-d8ff6b761c7c","added_by":"auto","created_at":"2021-08-05 16:41:12","extension":"png","order_by":13,"title":"Figure 13","display":"","copyAsset":false,"role":"figure","size":13375,"visible":true,"origin":"","legend":"% degradation plot of pure RhB and RhB over Co0.5Cu0.5SmxFe2-xO4; (0.0 and 0.09) nanoferrites, under simulated sunlight irradiation up to 180 min.","description":"","filename":"Fig13.png","url":"https://assets-eu.researchsquare.com/files/rs-770192/v1/d54ab7cf11ebce1a1898db02.png"},{"id":12153622,"identity":"84bd0452-88df-48d6-b6d0-f51ea6f6604d","added_by":"auto","created_at":"2021-08-05 16:32:12","extension":"png","order_by":14,"title":"Figure 14","display":"","copyAsset":false,"role":"figure","size":28009,"visible":true,"origin":"","legend":"(a-c): The plots of (a) At, (b) ln(Ao/At) and (c) (1/At) for RhB dye without and with Co0.5Cu0.5LaxFe2−xO4; (x=0.0 and 0.09) as photocatalysts.","description":"","filename":"Fig14.png","url":"https://assets-eu.researchsquare.com/files/rs-770192/v1/4bbe0e828637af5688737acb.png"},{"id":13708077,"identity":"0cf2801a-f125-4be0-88f4-5160659e8e65","added_by":"auto","created_at":"2021-09-17 14:05:57","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1972358,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-770192/v1/0d631217-86f6-4af0-832d-690eff753695.pdf"}],"financialInterests":"","formattedTitle":"\u003cp\u003eEnhancing the Magnetization, Dielectric Loss and Photocatalytic Activity of Co-cu Ferrite Nanoparticles Via the Substitution of Rare Earth Ions\u003c/p\u003e","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eIn day-to-day life environmental pollution from organic dyes became an intractable problem. Particularly, rhodamine B (RhB) organic dye can be vastly utilized in diverse purposes. Physically, RhB is bright-red in color with molecular formula C\u003csub\u003e28\u003c/sub\u003eH\u003csub\u003e31\u003c/sub\u003eClN\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, molecular weight 479 g/mol and water solubility (8\u0026ndash;15 g/L at 20\u0026deg;C). In fact, RhB can cause reliable environmental problems, besides its capability to make skin or eyes irritation [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. All these factors motivate us to generate effectual and cost-effective removal technique to overcome this environmental threat. Photocatalytic degradation of dyes using spinel ferrite nanoparticles is a salutary and environmentally friendly approach for dyes removal [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Recently, researches focus in the field of utilizing spinel ferrites as catalysis due to its moderately narrower band gap (~\u0026thinsp;2.0 eV), where can absorb both Vis. and UV radiations [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Moreover, the magnetic nature of spinel ferrites empowering its easy separation and retrieval of the ferrite powder again [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Kefeni et al., [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e] declared that cobalt and copper ferrites (CoFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u0026amp; CuFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e) besides their corresponding composites introduce higher photocatalytic performances. Consequently, we got excited to exploit a new nanoferrite containing both cobalt and copper cations (Co\u003csub\u003e0.5\u003c/sub\u003eCu\u003csub\u003e0.5\u003c/sub\u003eFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e) which doping with a rare earth element to augment their overall photocatalytic performance. Rather than their catalytic performances, Co\u003csub\u003e0.5\u003c/sub\u003eCu\u003csub\u003e0.5\u003c/sub\u003eFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e, also, acquire amazing properties among the reminder ferrite types [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Indeed, CoFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e is a promising material for diverse implementations based on its highest magneto-crystalline anisotropy (~\u0026thinsp;3\u0026times;10\u003csup\u003e5\u003c/sup\u003e J.m\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e) [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. This property make CoFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e has a feature suitable for storage devices applications. Basically, the crucial necessity for these magnetic materials utilizing in storage data that it should been have moderate saturation magnetization and high coercivity (H\u003csub\u003eC\u003c/sub\u003e), which are satisfied in CoFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e nanoparticles [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Additionally, CuFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e nanoparticles with the Jahn-Teller ion (Cu\u003csup\u003e2+\u003c/sup\u003e) have ubiquitous applications; based on their magneto-strictive property for the ferrite material [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Hence, in this investigation, by choosing Co\u003csub\u003e0.5\u003c/sub\u003eCu\u003csub\u003e0.5\u003c/sub\u003eFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e nanoferrite to be the pristine sample we can obtain the two features producing high H\u003csub\u003eC\u003c/sub\u003e; higher magneto-crystalline anisotropy (by CoFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e) besides higher magneto-strictive property (by CuFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e). Generally, Rare earth elements have auspicious effect on enhancement diverse nanoferrite systems [\u003cspan additionalcitationids=\"CR11\" citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Our research group, in the previous publication, declared that the substitution of lanthanum (La), as a rare earth element, into Zn-Mg ferrite system enhanced its physical properties besides improving its degradation efficiency [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. So, we are enthused to use La ion to enhance the features of another nanoferrites system as Co\u003csub\u003e0.5\u003c/sub\u003eCu\u003csub\u003e0.5\u003c/sub\u003eLa\u003csub\u003ex\u003c/sub\u003eFe\u003csub\u003e2\u0026minus;x\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e. Thus, by adding La\u003csup\u003e3+\u003c/sup\u003e ions, it is expected to obtain the following results; (1) moderate value of magnetization, where La\u003csup\u003e3+\u003c/sup\u003e ions have lower magnetic moment than Fe\u003csup\u003e3+\u003c/sup\u003e ions; (2) high value of coercivity, where La\u003csup\u003e3+\u003c/sup\u003e ions will generate spin-orbit coupling between 4f and 3d levels; (3) diminishing the energy gap, by energy levels creation by lanthanum electrons inside band gap, and interns enhance the photocatalytic property. In view of hopeful properties of spinel ferrite nanoparticles, current research investigates structural, magnetoelectric, optical features besides photocatalytic activity of Co\u003csub\u003e0.5\u003c/sub\u003eCu\u003csub\u003e0.5\u003c/sub\u003eLa\u003csub\u003ex\u003c/sub\u003eFe\u003csub\u003e2\u0026minus;x\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e nanoparticles; which is not investigated until now.\u003c/p\u003e"},{"header":"2. Materials And Methods","content":"\u003cp\u003ePure and La\u003csup\u003e3+\u003c/sup\u003e subrogated Co\u003csub\u003e0.5\u003c/sub\u003eCu\u003csub\u003e0.5\u003c/sub\u003eFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e nanoferrites were prepared through citrate combustion technique. In this approach metals nitrate; cobalt, copper, iron, lanthanum, with definite amounts, in addition to citric acid and ammonia solution were used. The combustion process of Co\u003csub\u003e0.5\u003c/sub\u003eCu\u003csub\u003e0.5\u003c/sub\u003eLa\u003csub\u003ex\u003c/sub\u003eFe\u003csub\u003e2\u0026minus;x\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e (CCL); (0\u0026thinsp;\u0026le;\u0026thinsp;x\u0026thinsp;\u0026le;\u0026thinsp;0.15; step 0.03) ferrite nanoparticles are reported minutely in an earlier publication [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. The yield CCL nanoferrites were investigated by XRD, FTIR, STEM-EDX besides its sundry features; dielectric, magnetic, optical and photocatalytic activity using the identical instruments in previous works [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e].\u003c/p\u003e"},{"header":"3. Results And Discussion","content":"\u003cdiv class=\"Section2\" id=\"Sec4\"\u003e\n \u003ch2\u003e3.1. Structural and morphologic investigations\u003c/h2\u003e\n \u003cdiv class=\"Section3\" id=\"Sec5\"\u003e\n \u003ch2\u003e3.1.1. XRD analysis\u003c/h2\u003e\n \u003cp\u003eFigure\u0026nbsp;1 manifests the XRD diffractograms of Co\u003csub\u003e0.5\u003c/sub\u003eCu\u003csub\u003e0.5\u003c/sub\u003eLa\u003csub\u003ex\u003c/sub\u003eFe\u003csub\u003e2\u0026minus;x\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e (CCL); (0\u0026thinsp;\u0026le;\u0026thinsp;x\u0026thinsp;\u0026le;\u0026thinsp;0.15) ferrite nanoparticles. The chart of pristine Co\u003csub\u003e0.5\u003c/sub\u003eCu\u003csub\u003e0.5\u003c/sub\u003eFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e nanoferrite sample (x\u0026thinsp;=\u0026thinsp;0.0) gives peaks at diffraction angles 2\u0026theta;\u0026thinsp;=\u0026thinsp;18.3, 30.26, 35.65, 37.20, 43.30, 53.60, 57.20, 62.80 and 74.24 that indexed to Miller notations as; 111, 220, 311, 222, 400, 422, 511, 440 and 533 in that order. Actually, these diffraction peaks are totally indexed to the FCC spinel lattice conforming to JCPDS cards (00-001-1121 and 01-077-0010). Also, the XRD of the reminder Co\u003csub\u003e0.5\u003c/sub\u003eCu\u003csub\u003e0.5\u003c/sub\u003eLa\u003csub\u003ex\u003c/sub\u003eFe\u003csub\u003e2\u0026minus;x\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e ferrite nanoparticles have diffraction peaks congruous to those observed in the pristine sample with slightly shift for diffraction angles; which confirm the spinel structure for all CCL nanoferrites. The substitution of La\u003csup\u003e3+\u003c/sup\u003e not produces any impurities, or foreign phase; confirming the wholly dissolution of La\u003csup\u003e3+\u003c/sup\u003e ions in CCL spinel lattice. Furthermore, the peaks are sharp and spread over the XRD patterns; affirming the nanocrystalline nature for all the investigated CCL nanoferrites.\u003c/p\u003e\n \u003cp\u003eThe lattice parameter (a\u003csub\u003eexp\u003c/sub\u003e) for all Co\u003csub\u003e0.5\u003c/sub\u003eCu\u003csub\u003e0.5\u003c/sub\u003eLa\u003csub\u003ex\u003c/sub\u003eFe\u003csub\u003e2\u0026minus;x\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e nanoparticles is calculated using the related Eq. in [\u003cspan class=\"CitationRef\"\u003e16\u003c/span\u003e]. Although the substitution process is a larger ion, La\u003csup\u003e3+\u003c/sup\u003e (1.032 \u0026Aring;), instead of a smaller one, Fe\u003csup\u003e3+\u003c/sup\u003e (0.645 \u0026Aring;) [\u003cspan class=\"CitationRef\"\u003e17\u003c/span\u003e], the lattice parameter did not introduce an increment behavior. It has a peculiar trend; decrement from (8.375\u0026Aring; at x\u0026thinsp;=\u0026thinsp;0.0) - (8.327\u0026Aring; at x\u0026thinsp;=\u0026thinsp;0.12) and augment for the nanoferrite with x\u0026thinsp;=\u0026thinsp;0.15 to 8.375\u0026Aring;, see Fig.\u0026nbsp;2. Three hypotheses are further suggested to interpret this enigma; two for the decrement behavior and one for the increment situation. Firstly, microstrains are the reason for the a\u003csub\u003eexp\u003c/sub\u003e decrement behavior, where make a compensation role against the large predictable crystal expansion. In fact, La\u003csup\u003e3+\u003c/sup\u003e ions (with its large radius) tend to enlarge the a\u003csub\u003eexp\u003c/sub\u003e values, then as a reparations for this alteration in spinel lattice, strain attempts to reduce it [\u003cspan class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e19\u003c/span\u003e]. Mariosi et al. [\u003cspan class=\"CitationRef\"\u003e20\u003c/span\u003e], reported alike behavior for decreasing lattice parameter of CoLa\u003csub\u003ex\u003c/sub\u003eFe\u003csub\u003e2\u0026minus;x\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e ferrite nanoparticles and explicated its behavior using the same reason. Secondly, bond dissociation energy (BDE) is another factor for interpreting this decrement behavior. In fact, BDE of (La\u0026ndash;O) is (619 kJ/mol) which be larger than that of (Fe\u0026ndash;O) (409 kJ/mol) [\u003cspan class=\"CitationRef\"\u003e21\u003c/span\u003e]. Consequently, the La\u0026ndash;O bond is shortened and sturdy; therefore, CCL lattice volume and consequently its parameter are decreased. As for the third hypothesis, it will be for the nanoferrite with x\u0026thinsp;=\u0026thinsp;0.15; where its a\u003csub\u003eexp\u003c/sub\u003e increment behavior can be interpreted in view of cations redistribution between tetrahedral (A) and octahedral (B) positions in CCL ferrite lattice. Actually, the ionic radii at A-sites are r\u003csub\u003eA\u003c/sub\u003e(Co\u003csup\u003e2+\u003c/sup\u003e\u0026rlm;)\u0026thinsp;=\u0026thinsp;0.58 \u0026Aring;, r\u003csub\u003eA\u003c/sub\u003e(Cu\u003csup\u003e2+\u003c/sup\u003e\u0026rlm;)\u0026thinsp;=\u0026thinsp;0.57 \u0026Aring;, r\u003csub\u003eA\u003c/sub\u003e(Fe\u003csup\u003e3+\u003c/sup\u003e\u0026rlm;)\u0026thinsp;=\u0026thinsp;0.49 \u0026Aring;, and at B-sites are r\u003csub\u003eB\u003c/sub\u003e(Co\u003csup\u003e2+\u003c/sup\u003e\u0026rlm;)\u0026thinsp;=\u0026thinsp;0.745 \u0026Aring;, r\u003csub\u003eB\u003c/sub\u003e(Cu\u003csup\u003e2+\u003c/sup\u003e\u0026rlm;)\u0026thinsp;=\u0026thinsp;0.73 \u0026Aring;, r\u003csub\u003eB\u003c/sub\u003e(Fe\u003csup\u003e3+\u003c/sup\u003e\u0026rlm;)\u0026thinsp;=\u0026thinsp;0.645 \u0026Aring;, r\u003csub\u003eB\u003c/sub\u003e (La\u003csup\u003e3+\u003c/sup\u003e\u0026rlm;)\u0026thinsp;=\u0026thinsp;1.032 \u0026Aring; [\u003cspan class=\"CitationRef\"\u003e17\u003c/span\u003e]. Then, the larger La cations will situate in B-site at expense of Fe\u003csup\u003e3+\u003c/sup\u003e ones, which forced some Fe\u003csup\u003e3+\u003c/sup\u003e cations to emigrate from B- to A-sites and consequently some Co\u003csup\u003e2+\u003c/sup\u003e and Cu\u003csup\u003e2+\u003c/sup\u003e, with their larger radii in B sites rather than in A-sites, will transfer from A- to B-sites; producing a\u003csub\u003eexp\u003c/sub\u003e increment behavior for the nanoferrite with (x\u0026thinsp;=\u0026thinsp;0.15). Ounacer et al. [\u003cspan class=\"CitationRef\"\u003e22\u003c/span\u003e], declared a similar attitude and expound its result with the same reasoning.\u003c/p\u003e\n \u003cp\u003eAlthough, crystallite size can be determined by diverse methods; Rietvled, Williamson-Hall (W-H) or Scherrer\u0026rsquo;s formula, W-H method is the most convenient one, because the strain components are involved. Consequently, the crystallite size (D\u003csub\u003eW\u0026minus;H\u003c/sub\u003e) besides lattice strain (\u0026epsilon;\u003csub\u003es\u003c/sub\u003e) of CCL ferrite nanoparticles is determined using Williamson-Hall method. Figure\u0026nbsp;3(a-f) shows the W-H graphs for all CCL nanoferrites, concerning the obtained diffraction peaks, with their better linear fitting; for determining crystallite size from intercept and lattice strain from the slope. Then crystallite size of CCL nanoferrites introduces distinctive trend; increment from 20.94 nm (at x\u0026thinsp;=\u0026thinsp;0.0) to 33.01 nm (at x\u0026thinsp;=\u0026thinsp;0.09) and then decrease step forward for x\u0026thinsp;=\u0026thinsp;0.12 and 0.15 to 30.27nm and 28.41 nm, respectively; see Fig.\u0026nbsp;2. This means that for small La\u003csup\u003e3+\u003c/sup\u003e content, up to the nanoferrite with x\u0026thinsp;=\u0026thinsp;0.09, the rates of nucleation and growth steps increase producing large size for crystallites [\u003cspan class=\"CitationRef\"\u003e23\u003c/span\u003e]. Therefore, the high concentrations of La\u003csup\u003e3+\u003c/sup\u003e ions (x\u0026thinsp;=\u0026thinsp;0.12 and 0.15) resort at grain boundaries, producing grain boundaries pinning, and interns shackle grain growth; resulting decreasing crystallite size trend for these two nanoferrite samples. On the other hand, lattice strains of CCL nanoferrites have positive values, see Fig. 2; demonstrating that all CCL nanoferrites possessing tensile strain with increasing values up to x\u0026thinsp;=\u0026thinsp;0.09 and then decrease for further La\u003csup\u003e3+\u003c/sup\u003e substitution. This increment behavior of lattice strain confirms the first hypothesis for lattice parameter decrement; as discussed above.\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv class=\"Section3\" id=\"Sec6\"\u003e\n \u003ch2\u003e3.1.2. Morphological characterization\u003c/h2\u003e\n \u003cp\u003eThe STEM-EDX of some selective samples, Co\u003csub\u003e0.5\u003c/sub\u003eCu\u003csub\u003e0.5\u003c/sub\u003eFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e, Co\u003csub\u003e0.5\u003c/sub\u003eCu\u003csub\u003e0.5\u003c/sub\u003eLa\u003csub\u003e0.09\u003c/sub\u003eFe\u003csub\u003e1.91\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e and Co\u003csub\u003e0.5\u003c/sub\u003eCu\u003csub\u003e0.5\u003c/sub\u003eLa\u003csub\u003e0.15\u003c/sub\u003eFe\u003csub\u003e1.85\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e as manifested in Fig. 4(a-f). The STEM graphs, Fig. 4(a, c and e), demonstrate the nanocrystalline nature of all the samples. It is plainly noticed the STEM micrographs possess almost spherical crystallites which indiscriminately distributed throughout the ferrite sample surface. Furthermore, CCL samples show agglomeration partly, which emanates from its constituents magnetic nature in addition to binding forces among surface nanoparticles. To corroborate the existence of the different metals in CCL ferrite samples, EDX micrographs were utilized to this mission as seen in Fig. 4(b, d and f). Actually, the EDX charts of CCL powders affirmed existence of metal cations; La, Co, Fe, Cu and O ions with no others traces of impurity; asserting the purity of CCL nanoferrite samples even substituted by a rare earth element (La). Furthermore La/Fe atomic percent matches with the desired ratios; affirmed from La peaks leveraging on account of iron; as in Fig. 4(d,f). Additionally, atomic% ratio of (Co\u0026thinsp;+\u0026thinsp;Cu)/Fe and (Co\u0026thinsp;+\u0026thinsp;Cu)/ (Fe\u0026thinsp;+\u0026thinsp;La) is just about 0.5; corroborating, once more, the prepared powders purity. Furthermore, the characteristic mapping of Co\u003csub\u003e0.5\u003c/sub\u003eCu\u003csub\u003e0.5\u003c/sub\u003eLa\u003csub\u003e0.15\u003c/sub\u003eFe\u003csub\u003e1.85\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e nanoferrite, for instance, Fig. 5, which reveals the constituent elements homogeneous distribution.\u003c/p\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv class=\"Section2\" id=\"Sec7\"\u003e\n \u003ch2\u003e3.2. Magnetic properties\u003c/h2\u003e\n \u003cdiv class=\"Section3\" id=\"Sec8\"\u003e\n \u003ch2\u003e3.2.1. Magnetic parameters of CCL nanoferrites\u003c/h2\u003e\n \u003cp\u003eThe hysteresis loops for the Co\u003csub\u003e0.5\u003c/sub\u003eCu\u003csub\u003e0.5\u003c/sub\u003eLa\u003csub\u003ex\u003c/sub\u003eFe\u003csub\u003e2\u0026minus;x\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e nanoferrites at room temperature (RT\u0026thinsp;=\u0026thinsp;303K), utilizing a field to \u0026plusmn;\u0026thinsp;20 kOe, are illustrated in Fig. 6. Then collected magnetic parameters; M\u003csub\u003eS\u003c/sub\u003e, M\u003csub\u003er\u003c/sub\u003e and H\u003csub\u003eC\u003c/sub\u003e of CCL nanoferrites are tabulated in Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e. The M\u003csub\u003eS\u003c/sub\u003e values are steadily diminishing with further substitution of La\u003csup\u003e3+\u003c/sup\u003e ion; from M\u003csub\u003eS\u003c/sub\u003e= 53.67 emug\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (for x\u0026thinsp;=\u0026thinsp;0.0) until M\u003csub\u003eS\u003c/sub\u003e= 42.75 emug\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (for x\u0026thinsp;=\u0026thinsp;0.15). In fact, M\u003csub\u003eS\u003c/sub\u003e values of ferrite materials are in straight proportionality with cations magnetic moment, which relies mainly on the unpaired (e) in the ferrite cations [\u003cspan class=\"CitationRef\"\u003e24\u003c/span\u003e]. Hence, this progressively decrement in M\u003csub\u003eS\u003c/sub\u003e values is a logical result to the magnetic moment difference for La/Fe cations, where La (2.78 \u0026micro;\u003csub\u003eB\u003c/sub\u003e) and Fe (5.92 \u0026micro;\u003csub\u003eB\u003c/sub\u003e); resulting deteriorating A-B super-exchange type [\u003cspan class=\"CitationRef\"\u003e25\u003c/span\u003e]. Then remanent magnetizations of CCL nanoferrites introduce the identical trend as saturation magnetization, with the same dialectics, from 27.79 to 21.53 emug\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e; with further La substitution.\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\u0026nbsp;\u003ctable border=\"1\" id=\"Tab1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eThe lattice parameter (a\u003csub\u003eexp\u003c/sub\u003e), crystallite size (D\u003csub\u003eW\u0026minus;H\u003c/sub\u003e), saturation magnetization (M\u003csub\u003es\u003c/sub\u003e), remanent magnetization (M\u003csub\u003er\u003c/sub\u003e) and coercivity (H\u003csub\u003eC\u003c/sub\u003e) initial permeability (𝜇\u003csub\u003ei\u003c/sub\u003e), anisotropy constant (K) and microwave frequency (\u0026omega;\u003csub\u003eM\u003c/sub\u003e) of CCL nanoferrites.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ex\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ea\u003csub\u003eexp\u003c/sub\u003e\u003c/p\u003e\n \u003cp\u003e(\u0026Aring;)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eD\u003csub\u003eW\u0026minus;H\u003c/sub\u003e\u003c/p\u003e\n \u003cp\u003e(nm)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eM\u003csub\u003eS\u003c/sub\u003e\u003c/p\u003e\n \u003cp\u003e(emu/g)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eM\u003csub\u003er\u003c/sub\u003e\u003c/p\u003e\n \u003cp\u003e(emu/g)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eH\u003csub\u003eC\u003c/sub\u003e\u003c/p\u003e\n \u003cp\u003e(Oe)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e𝜇\u003csub\u003ei\u003c/sub\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eK\u003c/p\u003e\n \u003cp\u003e(erg/cm\u003csup\u003e3\u003c/sup\u003e)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u0026omega;\u003csub\u003eM\u003c/sub\u003e\u003c/p\u003e\n \u003cp\u003e(GHz)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e8.375\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e20.94\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e53.67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e27.79\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1078.80\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e60311.66\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e11.87\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.03\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e8.375\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e21.56\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e51.53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e25.95\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1044.40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.02\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e56060.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e11.40\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.06\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e8.330\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e25.58\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e51.07\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e26.03\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e957.73\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.31\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e50949.24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e11.30\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.09\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e8.330\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e33.01\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e50.57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e25.46\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e922.19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.74\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e48578.28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e11.19\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e8.327\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e30.27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e43.86\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e22.03\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1048.60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e47907.91\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e9.70\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e8.375\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e28.41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e42.75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e21.53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1111.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e49487.58\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e9.46\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cdiv class=\"gridtable\"\u003e\u0026nbsp;\u003ctable border=\"1\" id=\"Tab2\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eThe kinetic rate constants (k\u003csub\u003e0\u003c/sub\u003e, k\u003csub\u003e1\u003c/sub\u003e and k\u003csub\u003e2\u003c/sub\u003e) and correlation coefficient (R\u003csup\u003e2\u003c/sup\u003e) for zeroth, first and second order reaction kinetics of RhB dye with and without CCL photocatalyst nanoparticles.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003eSample\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003eKinetic model parameters\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eZeroth order\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eFirst order\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSecond order\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eRhB\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ek\u003csub\u003e0\u003c/sub\u003e=-1.23\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;4\u003c/sup\u003e\u003c/p\u003e\n \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.977\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ek\u003csub\u003e1\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;1.76\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;4\u003c/sup\u003e\u003c/p\u003e\n \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.978\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ek\u003csub\u003e2\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;2.52\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;4\u003c/sup\u003e\u003c/p\u003e\n \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.980\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eRhB\u0026thinsp;+\u0026thinsp;Co\u003csub\u003e0.5\u003c/sub\u003eCu\u003csub\u003e0.5\u003c/sub\u003eFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ek\u003csub\u003e0\u003c/sub\u003e= -9.11\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;4\u003c/sup\u003e\u003c/p\u003e\n \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.998\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ek\u003csub\u003e1\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;0.00137\u003c/p\u003e\n \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.998\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ek\u003csub\u003e2\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;0.00207\u003c/p\u003e\n \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.994\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eRhB\u0026thinsp;+\u0026thinsp;Co\u003csub\u003e0.5\u003c/sub\u003eCu\u003csub\u003e0.5\u003c/sub\u003eSm\u003csub\u003e0.09\u003c/sub\u003eFe\u003csub\u003e1.91\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ek\u003csub\u003e0\u003c/sub\u003e= -0.00459\u003c/p\u003e\n \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.995\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ek\u003csub\u003e1\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;0.01498\u003c/p\u003e\n \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.868\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ek\u003csub\u003e2\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;0.08797\u003c/p\u003e\n \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.587\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cp\u003eFor H\u003csub\u003eC\u003c/sub\u003e values, it possesses a distinct trend; firstly presents a downward one, from 1078.8 to 922.19 Oe (for 0.0\u0026thinsp;\u0026le;\u0026thinsp;x\u0026thinsp;\u0026le;\u0026thinsp;0.09), and an upward one from 922.19 to 1111.3 Oe (for 0.09\u0026thinsp;\u0026le;\u0026thinsp;x\u0026thinsp;\u0026le;\u0026thinsp;0.15). This abnormal trend of H\u003csub\u003eC\u003c/sub\u003e for CCL nanoferrites can be argued as follow. Firstly, the introduction of the nonmagnetic La\u003csup\u003e3+\u003c/sup\u003e ions in CCL nanoferrites and its accompanied impact is diminishing saturation magnetization; therefore, the field needed to clobber this magnetization property to 0 levels, also, is decreased. Secondly the H\u003csub\u003eC\u003c/sub\u003e behavior in the range 0.09\u0026thinsp;\u0026le;\u0026thinsp;x\u0026thinsp;\u0026le;\u0026thinsp;0.15 has two reasoning. The first one is the CCL crystallite size impact; with its inversely proportional to coercivity [\u003cspan class=\"CitationRef\"\u003e26\u003c/span\u003e]. As shown in Fig.\u0026nbsp;2, crystallite size of CCL nanoferrites in the span 0.09\u0026thinsp;\u0026le;\u0026thinsp;x\u0026thinsp;\u0026le;\u0026thinsp;0.15, introduce a decrement behavior. Hence, as the crystallite size diminishes as the grain boundaries augment, i.e., the disordered regions increase and required coercivity field, H\u003csub\u003eC\u003c/sub\u003e, as a result increase. The second one is magneto-crystalline anisotropy of the substituted rare earth element (La) which increases the coercivity of the resultant ferrite. Actually, in materials containing heavy rare-earth elements, the spin\u0026ndash;orbit coupling is strong. Once magnetized, a high field must be utilized to reverse the magnetization direction after conquer the anisotropy produced from this coupling [\u003cspan class=\"CitationRef\"\u003e27\u003c/span\u003e]. Thus, with further La substitution, in the span 0.09\u0026thinsp;\u0026le;\u0026thinsp;x\u0026thinsp;\u0026le;\u0026thinsp;0.15, spin-orbit coupling and consequently the magneto-crystalline anisotropy of CCL nanoferrites increase and hence H\u003csub\u003eC\u003c/sub\u003e value increases. At last, it is concluded that the CCL samples have hard magnetic features which can be adjusted by La\u003csup\u003e3+\u003c/sup\u003e ions substitutions. Finally, the nanoferrite Co\u003csub\u003e0.5\u003c/sub\u003eCu\u003csub\u003e0.5\u003c/sub\u003eLa\u003csub\u003e0.15\u003c/sub\u003eFe\u003csub\u003e1.85\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e have a moderate saturation value 42.75 emu/g and the highest coercivity value 1111.3 Oe; candidate it to be an effective material for storage and recording applications.\u003c/p\u003e\n \u003cp\u003eAdditionally, initial permeability and anisotropy constant of the Co\u003csub\u003e0.5\u003c/sub\u003eCu\u003csub\u003e0.5\u003c/sub\u003eLa\u003csub\u003ex\u003c/sub\u003eFe\u003csub\u003e2\u0026minus;x\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e nanoferrites are calculated using the Ref. [\u003cspan class=\"CitationRef\"\u003e28\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e29\u003c/span\u003e], and tabulated in Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e\n \u003cdiv class=\"Equation\" id=\"Equa\"\u003e\n \u003cdiv class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e$$Anisotropy constant \\left(K\\right)=\\frac{{M}_{S}\\times {H}_{C}}{0.96}$$\u003c/div\u003e\n \u003c/div\u003e\n \u003cdiv class=\"Equation\" id=\"Equb\"\u003e\n \u003cdiv class=\"mathdisplay\" id=\"FileID_Equb\" name=\"EquationSource\"\u003e$$Initial permeability \\left({\\mu }_{i}\\right)=\\frac{{M}_{S}^{2}\\times {D}_{W-H}}{K}$$\u003c/div\u003e\n \u003c/div\u003e\n \u003cp\u003eIn fact, initial permeability has a distinctive attitude with La/Fe substitution process; increasing behavior for the nanoferrites with 0.00\u0026thinsp;\u0026le;\u0026thinsp;x\u0026thinsp;\u0026le;\u0026thinsp;0.09 and a decreasing one for x\u0026thinsp;=\u0026thinsp;0.12 and 0.15 nanoferrites. Although, saturation magnetization has a regular decrement behavior, \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\mu }_{i}\\)\u003c/span\u003e\u003c/span\u003e introduces this abnormal demeanor. Indeed the impact of crystallite size and anisotropy constant are decision makers for \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\mu }_{i}\\)\u003c/span\u003e\u003c/span\u003e behavior. Thus La substitution in Co-Cu nanoferrites, in the range 0.00\u0026thinsp;\u0026le;\u0026thinsp;x\u0026thinsp;\u0026le;\u0026thinsp;0.09, supports magnetic flux to pass and concentrate within these nanoferrites and inhibit it for x\u0026thinsp;=\u0026thinsp;0.12 and 0.15 nanoferrites. Contrary to expected results anisotropy constant introduces a decrement behavior with La/Fe substitution process. Where, it was expected that the spin-orbital coupling of La ions can enhance anisotropy property of these nanoferrites.\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv class=\"Section3\" id=\"Sec9\"\u003e\n \u003ch2\u003e3.2.2. High frequency response of CCL ferrite nanoparticles\u003c/h2\u003e\n \u003cp\u003eBasically, ferrite materials are the only ones available for microwave realm applications. Where for frequency (1 GHz\u0026thinsp;\u0026le;\u0026thinsp;f\u0026thinsp;\u0026le;\u0026thinsp;1000 GHz), the electrical energy is not transported via wires, but through electromagnetic waves which contained in wave-guides and transmitted through space. So we have to investigate the high frequency response of the prepared CCL nanoferrites to discover their applications in microwave fields. The microwave frequency (\u0026omega;\u003csub\u003eM\u003c/sub\u003e) values for all CCL nanoparticles are determined using Ref. [\u003cspan class=\"CitationRef\"\u003e30\u003c/span\u003e] and then saved in Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e. From the calculated \u0026omega;\u003csub\u003eM\u003c/sub\u003e values, 11.87 GHz\u0026ndash;9.46 GHz, CCL nanoferrites may be employing in high frequency applications. These values introduce a significant progress compared with other systems containing different rare earth elements with maximum \u0026omega;\u003csub\u003eM\u003c/sub\u003e value 8.4 GHz [\u003cspan class=\"CitationRef\"\u003e31\u003c/span\u003e].\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv class=\"Section3\" id=\"Sec10\"\u003e\n \u003ch2\u003e\u003cem\u003e3.2.3. Switching field distributions (SFD) response of CCL ferrite nanoparticles\u003c/em\u003e\u003c/h2\u003e\n \u003cp\u003eFigure\u0026nbsp;7, with its inset curve, shows the SFD plots (dM/dH vs. H) of all CCL nanoferrites. Physically, SFD plots scout the constituting cations exchange coupling. All SFD curves acquire higher values at large reverse field meanwhile introduce an almost constant one for higher fields; affirming the vigorous cations exchanges at higher reverse filed. Then inset plot, for large reverse field; confirming those figures are discontinuous. Analogous behavior was declared regarding different ferrites containing diverse rare earth elements [\u003cspan class=\"CitationRef\"\u003e31\u003c/span\u003e].\u003c/p\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv class=\"Section2\" id=\"Sec11\"\u003e\n \u003ch2\u003e3.3. Dielectric properties\u003c/h2\u003e\n \u003cp\u003eRegarding to dielectric bounds of La- substituted Co-Cu ferrite nanoparticles, special studies have been investigated. Actually, in frequency span (50Hz-5MHz at RT), dielectric parameters (dielectric constant, \u0026epsilon;\u0026prime;, and loss tangent, tan\u0026delta;) besides conductivity (\u0026sigma;\u003csub\u003eac\u003c/sub\u003e) for the synthesized system of Co\u003csub\u003e0.5\u003c/sub\u003eCu\u003csub\u003e0.5\u003c/sub\u003eLa\u003csub\u003ex\u003c/sub\u003eFe\u003csub\u003e2\u0026minus;x\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e nanoparticles have been studied. Fundamentally, \u0026epsilon;\u0026prime; refers to the amount of stored energy in the ferrite material, whereas tan\u0026delta; gives the energy loss out of phase rather than the response of the material, whilst \u0026sigma;\u003csub\u003eac\u003c/sub\u003e, determines the kind and mechanization of conduction within an applied field. Actually, the \u0026epsilon;\u0026prime; and \u0026sigma;\u003csub\u003eac\u003c/sub\u003e results of Co\u003csub\u003e0.5\u003c/sub\u003eCu\u003csub\u003e0.5\u003c/sub\u003eLa\u003csub\u003ex\u003c/sub\u003eFe\u003csub\u003e2\u0026minus;x\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e samples are determined using the Ref. [\u003cspan class=\"CitationRef\"\u003e32\u003c/span\u003e], whilst tan\u0026delta; result is getting directly from the instrument. As noticed in Fig.\u0026nbsp;8(a) \u0026epsilon;\u0026prime; decreases more speedily in the frequency then becomes dormant as frequency augment; which is the typical demeanor of all ferrite [\u003cspan class=\"CitationRef\"\u003e33\u003c/span\u003e]. Based on Koop\u0026apos;s model, any ferrite structure formed by arrangement of conducting regions (grains) estranged with lower conducting regions (grain boundaries) [\u003cspan class=\"CitationRef\"\u003e34\u003c/span\u003e]. Hence at lower frEq.\u0026nbsp;region various charge carriers transfer among dissimilar ions of the same element, e.g., Fe\u003csup\u003e2+\u003c/sup\u003e\u0026amp;Fe\u003csup\u003e3+\u003c/sup\u003e, which accumulate on grain boundaries (GBs); due to it high resistivity. This phenomenon is called Maxwell-Wagner (M-W) polarization which gives a high value of dielectric constant which decreases slowly with frequency [\u003cspan class=\"CitationRef\"\u003e35\u003c/span\u003e]. At higher frEq.\u0026nbsp;these charges within grains itself cannot pursue the frequency of the applicable field, and then polarization diminishing and almost stable \u0026epsilon;\u0026prime; level is obtained [\u003cspan class=\"CitationRef\"\u003e36\u003c/span\u003e]. As observed from inset curve of Fig.\u0026nbsp;8(a), the dielectric constant of CCL nanoferrites decrease gradually with further La\u003csup\u003e3+\u003c/sup\u003e substitution in view of two respects. The first one is the electron hopping among Fe\u003csup\u003e2+\u003c/sup\u003e\u0026amp;Fe\u003csup\u003e3+\u003c/sup\u003eions reduces by La\u003csup\u003e3+\u003c/sup\u003e/Fe\u003csup\u003e3+\u003c/sup\u003e ions replacement. The second is account for the increment of resistivity, originated from 3d-4f coupling of La ions, where the relation between resistivity and \u0026epsilon;\u0026prime; is inversely proportion [\u003cspan class=\"CitationRef\"\u003e37\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eAs for the \u0026sigma;\u003csub\u003eac\u003c/sub\u003e behavior, it has a growing attitude with frequency; see Fig. 8(b). Many workers declared that presence similarity for \u0026sigma;\u003csub\u003eac\u003c/sub\u003e and \u0026epsilon;\u0026prime; mechanisms for ferrite materials [\u003cspan class=\"CitationRef\"\u003e38\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e40\u003c/span\u003e]. Consequently, the preceding interpretation of \u0026epsilon;\u0026apos; for CCL nanoferrites is benefit for understanding \u0026sigma;\u003csub\u003eac\u003c/sub\u003e behavior with frequency. Hence, as noticed from the inset curve of Fig. 8(b), \u0026sigma;\u003csub\u003eac\u003c/sub\u003e decreases with the augment in La content. As for conductivity frequency dependence, the crowd of charges on CCL nanoferrites GBs is the major cause for the independent regime in \u0026sigma;\u003csub\u003eac\u003c/sub\u003e plot. By increasing frequency, the impact of interior Gs of CCL nanoferrites and charge carriers transfer are accountable for \u0026sigma;\u003csub\u003eac\u003c/sub\u003e increment demeanor. Generally, frequency acts to augment the conduction phenomenon by its propelling diverse charge carriers between the conduction positions [\u003cspan class=\"CitationRef\"\u003e41\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eThe tan\u0026delta; of the investigated CCL ferrite nanoparticles is given in Fig.\u0026nbsp;8(c). In fact, the decreases in tan\u0026delta; value are noticed with further increasing frequency and with La\u003csup\u003e3+\u003c/sup\u003e ions substitution; see the inset curve of Fig. 8(c). This behavior of tan\u0026delta; can be justified using two facts. With increasing La content in CCL nanoferrites, polarization (\u0026epsilon;\u0026prime;) depressed and also the accompanied loss decrease; this is the first reason. The other cause for tan\u0026delta; behavior is the CCL crystallite size by it\u0026apos;s inversely proportion with it [\u003cspan class=\"CitationRef\"\u003e42\u003c/span\u003e].\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv class=\"Section2\" id=\"Sec12\"\u003e\n \u003ch2\u003e3.4. Optical studies\u003c/h2\u003e\n \u003cdiv class=\"Section3\" id=\"Sec13\"\u003e\n \u003ch2\u003e3.4.1. UV-Visible absorption and optical energy gap\u003c/h2\u003e\n \u003cp\u003eFor the present Co\u003csub\u003e0.5\u003c/sub\u003eCu\u003csub\u003e0.5\u003c/sub\u003eLa\u003csub\u003ex\u003c/sub\u003eFe\u003csub\u003e2\u0026minus;x\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e; (x\u0026thinsp;=\u0026thinsp;0.0, 0.03, 0.06, 0.09, 0.12, 0.15) ferrite nanoparticles, one can notice a broad absorption band positioned nearly at 500 nm; as shown in Fig.\u0026nbsp;9. Generally, ferrite materials are opaque at wavelengths\u0026thinsp;\u0026le;\u0026thinsp;200 nm; at which the photon energy is \u0026ge;\u0026thinsp;optical band gap (E\u003csub\u003eg\u003c/sub\u003e), which is required for transition from valence to conduction bands [\u003cspan class=\"CitationRef\"\u003e43\u003c/span\u003e]. The E\u003csub\u003eg\u003c/sub\u003e values of Co\u003csub\u003e0.5\u003c/sub\u003eCu\u003csub\u003e0.5\u003c/sub\u003eLa\u003csub\u003ex\u003c/sub\u003eFe\u003csub\u003e2\u0026minus;x\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e nanoferrites can be calculated by extrapolating the linear portion curve of (\u0026alpha;h\u0026nu;)\u003csup\u003e2\u003c/sup\u003e vs. photon energy (h\u0026nu;) to (\u0026alpha;h\u0026nu;)\u003csup\u003e2\u003c/sup\u003e= 0; for direct allowed transition (Tauc\u0026apos;s plot) (Fig.\u0026nbsp;10(a-f)) [\u003cspan class=\"CitationRef\"\u003e44\u003c/span\u003e]. From Tauc\u0026apos;s plot, E\u003csub\u003eg\u003c/sub\u003e values of CCL nanoferrites are determined. Basically, the band gap can be tuned based on several factors: e.g., crystallite size, structural parameter and impurities. The calculated E\u003csub\u003eg\u003c/sub\u003e values of CCL nanoferrites are displayed in Fig. 11. In fact our energy gap possesses a peculiar demeanor; a red shift from 3.04 eV to 2.46 eV (for 0.0\u0026thinsp;\u0026le;\u0026thinsp;x\u0026thinsp;\u0026le;\u0026thinsp;0.09) and a blue shift from 2.46 eV to 2.98 eV for (0.09\u0026thinsp;\u0026le;\u0026thinsp;x\u0026thinsp;\u0026le;\u0026thinsp;0.15). A similar E\u003csub\u003eg\u003c/sub\u003e behavior was observed in an earlier work for Zn-Mg nanoferrites [\u003cspan class=\"CitationRef\"\u003e13\u003c/span\u003e]. This behavior of E\u003csub\u003eg\u003c/sub\u003e can be explained trough two scenarios. Firstly, further La content generates a lot of donor levels in the forbidden band, producing E\u003csub\u003eg\u003c/sub\u003e decrement. Secondly, this tendency of E\u003csub\u003eg\u003c/sub\u003e may be accredited to the decrement attitude of CCL nanoferrites crystallite size in the range 0.09\u0026thinsp;\u0026le;\u0026thinsp;x\u0026thinsp;\u0026le;\u0026thinsp;0.15 (see Fig. 2); where the relationship between the band gap and particle size is an inversely one [\u003cspan class=\"CitationRef\"\u003e15\u003c/span\u003e]. Also the augmentation of conductivity of Co-Cu nanoferrites with further La\u003csup\u003e3+\u003c/sup\u003e substituting confirms the E\u003csub\u003eg\u003c/sub\u003e behavior in that range.\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv class=\"Section3\" id=\"Sec14\"\u003e\n \u003ch2\u003e3.4.2. Photocatalytic activity\u003c/h2\u003e\n \u003cp\u003eThe influence of Co\u003csub\u003e0.5\u003c/sub\u003eCu\u003csub\u003e0.5\u003c/sub\u003eLa\u003csub\u003ex\u003c/sub\u003eFe\u003csub\u003e2\u0026minus;x\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e nanoferrites on photo-catalytic dye degradation of Rhodamine B (RhB) was investigated using absorption spectra. However, the E\u003csub\u003eg\u003c/sub\u003e of photocatalyst governs the absorbed wavelength and produces electron-hole pairs. The nanoferrite specimens with x\u0026thinsp;=\u0026thinsp;0.0 and 0.09 La\u003csup\u003e3+\u003c/sup\u003e were chosen for this investigation because x\u0026thinsp;=\u0026thinsp;0.0 represent the pristine ferrite and x\u0026thinsp;=\u0026thinsp;0.09 has the least E\u003csub\u003eg\u003c/sub\u003e value. This choice based on the opposite relation between E\u003csub\u003eg\u003c/sub\u003e and photodegradation behavior [\u003cspan class=\"CitationRef\"\u003e13\u003c/span\u003e]. Moreover, the replacement of rare earth cations in Co-Cu ferrite gives good optical absorption in visible range point toward enhanced photodegradation efficiency. As a consequence of metastable La-4f energy levels creation near the lower edge of the conduction band of Co-Cu ferrite, this indicates the decrease in the band gap. A further factor is the defects resulting from La doping which act as trapping centers and simplify the split-up of photogenerated electron-hole pairs and increase the life time of charge carrier [\u003cspan class=\"CitationRef\"\u003e45\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eThe photo-catalytic degradation efficiency is obtained from the variation in Absorbance for the reason of direct relation between concentration (c) and absorbance (A) [\u003cspan class=\"CitationRef\"\u003e46\u003c/span\u003e]. It is well known that, the self-degradation efficiency of RhB (without catalyst) is very small value for dye disposal [\u003cspan class=\"CitationRef\"\u003e13\u003c/span\u003e]. Figure\u0026nbsp;12(a-c) manifests photocatalytic degradation of RhB and RhB\u0026thinsp;+\u0026thinsp;Co\u003csub\u003e0.5\u003c/sub\u003eCu\u003csub\u003e0.5\u003c/sub\u003eLa\u003csub\u003ex\u003c/sub\u003eFe\u003csub\u003e2\u0026minus;x\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e (x\u0026thinsp;=\u0026thinsp;0.0, and 0.09) irradiated under solar light at variable times (from 0-180 min). The reduction in absorbance intensity designates enhancement in dye degradation. The mechanism for RhB photodegradation of the nanoferrite in which x\u0026thinsp;=\u0026thinsp;0.9 La (as an example) is understood with aid of some of free radicals. All the spectra evident the characteristic absorption curves of RhB with a peak, at ~\u0026thinsp;552 nm and a shoulder at ~\u0026thinsp;512 nm [\u003cspan class=\"CitationRef\"\u003e47\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eThe % degradation of samples is determined via the equation listed in Ref. [\u003cspan class=\"CitationRef\"\u003e48\u003c/span\u003e]. Figure 13 illustrates % degradation for pure RhB and RhB over CCL nanoferrites with (x\u0026thinsp;=\u0026thinsp;0.0 and 0.09). The % degradation, after irradiation for 180 min, of pure RhB dye is just 3.31%; which is an unsatisfactory impact. As for the % degradation for RhB over CCL nanoferrites with (x\u0026thinsp;=\u0026thinsp;0.0 and 0.09) photocatalysts is enlarged; (22.37% and 94.50%, respectively). Hence, the catalytic recital was enhanced with La/Fe substitution process via the next most probable discussion. When the electrons were excited from valence band (VB) to created energy level CCL conduction band (CB) in the sample under sunlight irradiation, the photogenerated holes in VB react with surface water or hydroxyl ion to yield \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\text{O}\\text{H}}^{\\bullet }\\)\u003c/span\u003e\u003c/span\u003e radical, which is a good oxidant in the degradation of RhB and instantaneously, electrons in the CB reacts with adsorbed oxygen molecule to yield \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\text{O}}_{2}^{.-}\\)\u003c/span\u003e\u003c/span\u003e. Moreover, it combines with H\u003csup\u003e+\u003c/sup\u003e to yield \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\text{H}\\text{O}}_{2}\\)\u003c/span\u003e\u003c/span\u003e. [\u003cspan class=\"CitationRef\"\u003e49\u003c/span\u003e], which react with trapped electrons to yield \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\text{O}\\text{H}}^{\\bullet }\\)\u003c/span\u003e\u003c/span\u003e [\u003cspan class=\"CitationRef\"\u003e50\u003c/span\u003e]. It is obvious that, \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\text{O}\\text{H}}^{\\bullet }\\)\u003c/span\u003e\u003c/span\u003e, \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\text{H}\\text{O}}_{2}\\)\u003c/span\u003e\u003c/span\u003e., \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\text{O}}_{2}^{.-}\\)\u003c/span\u003e\u003c/span\u003e and \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({h}_{VB}^{+}\\)\u003c/span\u003e\u003c/span\u003e are active species included in RhB photodegredation. Regarding the previous argument, the photochemical reaction for the degradation of RhB under sunlight irradiation of Co-Cu-La ferrite photocatalyst was summarized as follows [\u003cspan class=\"CitationRef\"\u003e13\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003e\u003cem\u003eCo\u003c/em\u003e \u003csub\u003e\u0026nbsp;\u003cem\u003e0.5\u003c/em\u003e\u0026nbsp;\u003c/sub\u003e \u003cem\u003eCu\u003c/em\u003e \u003csub\u003e\u0026nbsp;\u003cem\u003e0.5\u003c/em\u003e\u0026nbsp;\u003c/sub\u003e \u003cem\u003eLa\u003c/em\u003e \u003csub\u003e\u0026nbsp;\u003cem\u003e0.09\u003c/em\u003e\u0026nbsp;\u003c/sub\u003e \u003cem\u003eFe\u003c/em\u003e \u003csub\u003e\u0026nbsp;\u003cem\u003e1.91\u003c/em\u003e\u0026nbsp;\u003c/sub\u003e \u003cem\u003e-O\u003c/em\u003e \u003csub\u003e\u0026nbsp;\u003cem\u003e4\u003c/em\u003e\u0026nbsp;\u003c/sub\u003e\u0026thinsp;\u003cem\u003e+\u0026thinsp;h\u0026nu;\u003c/em\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\to\\)\u003c/span\u003e\u003c/span\u003e \u003cem\u003eCo\u003c/em\u003e\u003csub\u003e\u003cem\u003e0.5\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eCu\u003c/em\u003e\u003csub\u003e\u003cem\u003e0.5\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eLa\u003c/em\u003e\u003csub\u003e\u003cem\u003e0.09\u003c/em\u003e\u003c/sub\u003e\u003cem\u003e-Fe\u003c/em\u003e\u003csub\u003e\u003cem\u003e1.91\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eO\u003c/em\u003e\u003csub\u003e\u003cem\u003e4\u003c/em\u003e\u003c/sub\u003e \u003cem\u003e+ (e\u003c/em\u003e\u003csup\u003e\u003cem\u003e\u0026minus;\u003c/em\u003e\u003c/sup\u003e \u003cem\u003eand h\u003c/em\u003e\u003csup\u003e\u003cem\u003e+\u003c/em\u003e\u003c/sup\u003e\u003cem\u003e)\u003c/em\u003e\u003c/p\u003e\n \u003cp\u003e\u003cem\u003ee\u003c/em\u003e \u003csup\u003e\u0026nbsp;\u003cem\u003e\u0026minus;\u003c/em\u003e\u0026nbsp;\u003c/sup\u003e \u003cem\u003e+\u003c/em\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({O}_{2}\\)\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\to O}_{2}^{.-}\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e\n \u003cp\u003e\u003cem\u003eh\u003c/em\u003e \u003csup\u003e\u0026nbsp;\u003cem\u003e+\u003c/em\u003e\u0026nbsp;\u003c/sup\u003e \u003cem\u003e+\u003c/em\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({HO}_{2}\\)\u003c/span\u003e\u003c/span\u003e \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\to {H}^{+}\\)\u003c/span\u003e\u003c/span\u003e\u003cem\u003e+\u003c/em\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({OH}^{\\bullet }\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e\n \u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u0026nbsp;\u003cspan class=\"mathinline\"\u003e\\({{O}_{2}^{.-}+H}^{+}{\\to HO}_{2}\\)\u003c/span\u003e\u0026nbsp;\u003c/span\u003e., \u003cem\u003e2e\u003c/em\u003e\u003csup\u003e\u003cem\u003e\u0026minus;\u003c/em\u003e\u003c/sup\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({+HO}_{2}\\)\u003c/span\u003e\u003c/span\u003e.\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(+\\)\u003c/span\u003e\u003c/span\u003e \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({H}^{+}{\\to OH}^{\\bullet }+{OH}^{-}\\)\u003c/span\u003e\u003c/span\u003e \u003cem\u003eand h\u003c/em\u003e\u003csup\u003e\u003cem\u003e+\u003c/em\u003e\u003c/sup\u003e \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({+ OH}^{-}\\)\u003c/span\u003e\u003c/span\u003e.\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\to OH}^{\\bullet }\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e\u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u0026nbsp;\u003cspan class=\"mathinline\"\u003e\\({OH}^{\\bullet }\\)\u003c/span\u003e\u0026nbsp;\u003c/span\u003e, \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({HO}_{2}\\)\u003c/span\u003e\u003c/span\u003e., \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({O}_{2}^{.-}\\)\u003c/span\u003e\u003c/span\u003e, \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({h}_{VB}^{+}\\)\u003c/span\u003e\u003c/span\u003e\u003cem\u003e+RhB\u003c/em\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\to Degraded products\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e\u003cp\u003eThese radicals, formed from the previous steps, can interact with the toxic RhB dyes, converting its complex molecules to simple and non-toxic ones. Dhiman et al. [\u003cspan class=\"CitationRef\"\u003e51\u003c/span\u003e] in previous work obtain comparable mechanisms for photocatalytic behaviors for CoFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e ferrite doped with various rare earths.\u003c/p\u003e\u003cp\u003eTo distinguish the photocatalytic activity protocol of CCL photocatalyst, the three kinetic models (0th, 1st and 2nd orders) are determined using the following equations [\u003cspan class=\"CitationRef\"\u003e52\u003c/span\u003e].\u003c/p\u003e\u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u0026nbsp;\u003cspan class=\"mathinline\"\u003e\\({A}_{t}={A}_{o}-{k}_{o}t\\)\u003c/span\u003e\u0026nbsp;\u003c/span\u003e, \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({A}_{t}={A}_{o}{e}^{-{k}_{1}t}\\)\u003c/span\u003e\u003c/span\u003e,\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\frac{1}{{A}_{t}}=\\frac{1}{{A}_{o}}+{k}_{2}t\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e\n \u003cp\u003ewhere A\u003csub\u003et\u003c/sub\u003e and A\u003csub\u003eo\u003c/sub\u003e are absorbance of RhB dye after and before irradiation time (t), respectively. For this mission, the plots of A\u003csub\u003et\u003c/sub\u003e, ln(A\u003csub\u003eo\u003c/sub\u003e/A) and 1/A\u003csub\u003et\u003c/sub\u003e versus time are determined with their linear fitting; see Fig. 14(a-c). The three kinetic constants (k\u003csub\u003e0\u003c/sub\u003e, k\u003csub\u003e1\u003c/sub\u003e and k\u003csub\u003e2\u003c/sub\u003e) of zeroth, first and second order reaction kinetics, respectively of RhB and (RhB\u0026thinsp;+\u0026thinsp;CCL samples (x\u0026thinsp;=\u0026thinsp;0.0 and 0.09) are calculated and tabulated in Table\u0026nbsp;2. Also, correlation coefficient (R\u003csup\u003e2\u003c/sup\u003e) of each order kinetic is calculated and inserted in Table\u0026nbsp;2. The second order is the most favorable model for pure RhB, where its R\u003csup\u003e2\u003c/sup\u003e value is 0.980 (the highest value compared with other orders). As for RhB over CCL sample with (x\u0026thinsp;=\u0026thinsp;0.0) has R\u003csup\u003e2\u003c/sup\u003e value 0.998 for both zeroth and first-orders; declaring that these models are favorable models for degradation. Meanwhile for RhB over CCL sample with (x\u0026thinsp;=\u0026thinsp;0.09) has R\u003csup\u003e2\u003c/sup\u003e value 0.995 for zeroth; demonstrating this model is the most suitable model for degradation of this sample. Finally, the k\u003csub\u003e0\u003c/sub\u003e, k\u003csub\u003e1\u003c/sub\u003e and k\u003csub\u003e2\u003c/sub\u003e values for RhB dye degradations in presence of CCL nanoferrite powders are higher than those of pristine RhB dye; see Table 2. These outcomes confirm the CCL nanoferrites are capable of enhancing the RhB dye degradation efficiency in industrial community.\u003c/p\u003e\n \u003c/div\u003e\n\u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eA sequence of lanthanum substituted cobalt-copper (Co\u003csub\u003e0.5\u003c/sub\u003eCu\u003csub\u003e0.5\u003c/sub\u003eLa\u003csub\u003ex\u003c/sub\u003eFe\u003csub\u003e2-x\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e; 0x\u0026le;0.15) (CCL)\u0026nbsp;were prepared via a combustion approach.\u0026nbsp;XRD charts of CCL samples affirmed the spinel structure for the prepared powders. Although the substitution process is a larger ion, La\u003csup\u003e3+\u003c/sup\u003e (1.032 \u0026Aring;), instead of a smaller one, Fe\u003csup\u003e3+\u003c/sup\u003e (0.645 \u0026Aring;), the lattice parameter did not introduce an increment behavior. It has a peculiar trend; decrement from (8.375\u0026Aring; at x= 0.0) to (8.327\u0026Aring; at x= 0.12) then augment for the nanoferrite with x=0.15 to 8.375\u0026Aring;. The crystallite size of CCL nanoferrites introduces a distinctive trend; increment from (20.94 nm at x= 0.0) to (33.01 nm at x= 0.09) then decrease step forward for x=0.12 and 0.15 to 30.27nm and 28.41 nm, respectively. STEM micrographs possess almost spherical crystallites which indiscriminately distributed throughout the ferrite sample surface. M\u003csub\u003eS\u003c/sub\u003e values are steadily diminishing with further substitution of La\u003csup\u003e3+\u003c/sup\u003e ion; from M\u003csub\u003eS\u003c/sub\u003e= 53.67 emug\u003csup\u003e-1\u003c/sup\u003e (for x= 0.0) to M\u003csub\u003eS\u003c/sub\u003e= 42.75 emug\u003csup\u003e-1\u003c/sup\u003e at (x= 0.15). H\u003csub\u003eC\u003c/sub\u003e values, it possesses a distinct trend; firstly presents a downward one, from 1078.8 to 922.19 Oe (for 0.0\u0026le;x\u0026le;0.09), and an upward one from 922.19 to 1111.3 Oe (for 0.09\u0026le;x\u0026le;0.15). Dielectric constant and loss tangent have a decrement behavior with frequency and with substitution of La ions. E\u003csub\u003eg\u003c/sub\u003e has a peculiar demeanor; a red shift from 3.04 eV to 2.46 eV (for 0.0\u0026le;x\u0026le;0.09) and a blue shift from 2.46 eV to 2.98 eV for (0.09\u0026le;x\u0026le;0.15). The % degradation for RhB over CCL nanoferrites with (x=0.0 and 0.09) photocatalysts is enlarged; (22.37% and 94.50%, respectively). The nanoferrite Co\u003csub\u003e0.5\u003c/sub\u003eCu\u003csub\u003e0.5\u003c/sub\u003eLa\u003csub\u003e0.15\u003c/sub\u003eFe\u003csub\u003e1.85\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e has a moderate saturation magnetization, highest coercivity and lowest loss which can be a suitable candidate for data storage applications. Moreover, Co\u003csub\u003e0.5\u003c/sub\u003eCu\u003csub\u003e0.5\u003c/sub\u003eLa\u003csub\u003e0.15\u003c/sub\u003eFe\u003csub\u003e1.85\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e can be utilized as a photocatalyst for RhB effluents removal with degradation efficiency 94.50% at 180 min.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAcknowledgements\u003c/h2\u003e \u003cp\u003e\u0026ldquo;This research work was funded by Institutional Fund Projects under grant no. (IFPHI-165-247-2020). Therefore, authors gratefully acknowledge technical and financial support from the Ministry of Education and King Abdulaziz University, DSR, Jeddah, Saudi Arabia\u0026rdquo;.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eMansour SF, Wageh S, Al-Wafi R, Abdo MA (2021) Enhanced magnetic, dielectric properties and photocatalytic activity of J Mater Sci: Mater Electron doped Mg-Zn ferrite nanoparticles by virtue of Sm\u003csup\u003e3+\u003c/sup\u003e role. J Alloys Compd 856:157437\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAlSalka Y, Granone LI, Ramadan W, Hakki A, Dillert R, Bahnemann DW (2019) Iron based photocatalytic and photoelectrocatalytic nano-structures: Facts, perspectives, and expectations. Appl Catal B Environ 244:1065\u0026ndash;1095\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKarakas IH (2021) The effects of fuel type onto the structural, morphological, magnetic and photocatalytic properties of nanoparticles in the synthesis of cobalt ferrite nanoparticles with microwave assisted combustion method. Ceram Int 47:5597\u0026ndash;5609\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJadhav SA, Khedkar MV, Andhare DD, Gopale SB, Jadhav KM (2021) Visible light photocatalytic activity of magnetically diluted Ni\u0026ndash;Zn spinel ferrite for active degradation of rhodamine B. Ceram Int 10:13980\u0026ndash;13993\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKefeni KK, Mamba BB (2020) Photocatalytic application of spinel ferrite nanoparticles and nanocomposites in wastewater treatment. 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J Taiwan Inst Chem E 68:506\u0026ndash;513\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAref AA, Qahtan S, Husain A, Somvanshi W, Khan YK, Manea (2020) J Mater Sci: Mater Electron 31:9335\u0026ndash;9351\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"CCL, RhB, nanocrystals synthesized, STEM-EDX, anisotropy ","lastPublishedDoi":"10.21203/rs.3.rs-770192/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-770192/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis study reports the impact of lanthanum substituted Co-Cu ferrite nanoparticles on the RhB dye disposal. Moreover, a complete investigation for the structural, magnetic and optical properties for Co\u003csub\u003e0.5\u003c/sub\u003eCu\u003csub\u003e0.5\u003c/sub\u003eLa\u003csub\u003ex\u003c/sub\u003eFe\u003csub\u003e2-x\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e (CCL) nanoferrites was executed. These nanocrystals synthesized via a combustion approach with a peculiar lattice parameter behavior; which discussed through three hypotheses. STEM-EDX micrographs of some selective samples confirm the nanocrystalline nature with presence of all constituents’ chemical elements CCL nanoferrites. The saturation magnetization of CCL nanoferrites was tuned with La\u003csup\u003e3+\u003c/sup\u003e ions substitution. Contrary to the expected results, anisotropy constant introduced a decrement behavior with La/Fe substitution process. The microwave frequency (ω\u003csub\u003eM\u003c/sub\u003e) values for all CCL nanoparticles are in the range 11.87 GHz–9.46 GHz. The band gap has a peculiar behavior; a red shift and followed by a blue one. Through photodegradation testing, we explicate the RhB degradation mechanisms over our CCL nanoferrites. The nanoferrite Co\u003csub\u003e0.5\u003c/sub\u003eCu\u003csub\u003e0.5\u003c/sub\u003eLa\u003csub\u003e0.15\u003c/sub\u003eFe\u003csub\u003e1.85\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e has a moderate saturation magnetization, highest coercivity, and lowest loss which is a suitable candidate for data recording applications, furthermore can be utilized as a photocatalyst for RhB effluents removal with degradation efficiency 94.50% at 180 min solar radiation.\u0026nbsp;\u003c/p\u003e","manuscriptTitle":"Enhancing the Magnetization, Dielectric Loss and Photocatalytic Activity of Co-cu Ferrite Nanoparticles Via the Substitution of Rare Earth Ions","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2021-08-05 16:32:09","doi":"10.21203/rs.3.rs-770192/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"ade7c467-91a3-4889-b99c-ba67cc2c1fd2","owner":[],"postedDate":"August 5th, 2021","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":6231433,"name":"Ceramics"}],"tags":[],"updatedAt":"2021-08-05T16:32:11+00:00","versionOfRecord":[],"versionCreatedAt":"2021-08-05 16:32:09","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-770192","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-770192","identity":"rs-770192","version":["v1"]},"buildId":"_2-kVJe1T_tPrBINL-cwx","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}