Photoluminescent properties of Eu 3+ , Tb 3+ doped SrWO 4 nanoparticles prepared by ethylene glycol route

Photoluminescent properties of Eu 3+ , Tb 3+ doped SrWO 4 nanoparticles prepared by ethylene glycol route | 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 Photoluminescent properties of Eu 3+ , Tb 3+ doped SrWO 4 nanoparticles prepared by ethylene glycol route Kongbrailatpam Gayatri Sharma This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9151142/v1 This work is licensed under a CC BY 4.0 License Status: Under Revision Version 1 posted 14 You are reading this latest preprint version Abstract A series of SrWO 4 doped with Eu 3+ and Tb 3+ nanoparticles were prepared by co-precipitation method using ethylene glycol as the solvent yielding highly crystalline phosphors. The phosphors were characterized by the X-ray diffraction (XRD), FT-IR spectroscopy and Transmission electron microscopy (TEM). The FT-IR spectroscopy was used to study the vibrations present in the prepared nanoparticles. The spectrum shows prominent bands at around 3300, 2853, 2890, 2924, 1383, 1650, 820 and 430–440 cm − 1 ; corresponding to H–O–H bending and O–H stretching vibrations of water molecules present on the surface of nanoparticles and the O–W–O asymmetric stretching vibration of the WO 4 2− tetrahedron. Characterization confirms single-phase formation, controlled morphology, and characteristic luminescence emission which can prove to be suitable for multicolour emission applications. The photoluminescence properties of the prepared nanoparticles were also studied and it is observed that by increasing the doping concentration of rare earth ions in the host i.e. SrWO 4 , the emission intensity of the phosphors also increased and after reaching its optimum concentration, the luminescence intensity decreased drastically. For Eu 3+ and Tb 3+ , the optimum concentrations are 10 and 7 at. %, respectively. Phosphors Nanoparticles Photoluminescence Charge transfer and Rare-earths Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 1. Introduction Alkaline-earth-metal tungstates AWO 4 (A = Ca, Sr, Ba) form a significant family of scheelite-type inorganic materials which are recognized for their structural stability and versatile optoelectronic properties [1–2]; showing wide applications in thermoluminescence, lasers and as excellent host material. Out of these alkaline-earth tungstates, SrWO 4 is an important electro-optical material which has an intrinsic strong blue emission band; however, its luminescence covers a broad range of wavelengths that are insensitive to external changes [3]. Over the past few decades, the luminescent properties of rare-earth ions have been the subject of extensive research due to their unique electronic configurations, specifically the rich energy level structures within the 4f orbitals, rare-earth materials exhibit diverse and abundant emission spectra [4]. Lanthanide-activated (Eu³⁺, Tb³⁺, Sm³⁺, and Dy³⁺) SrWO₄ phosphors are reported to produce sharp, characteristic red, green, and blue emissions, making them promising candidates for efficient LED and optical device applications. [5]. A major challenge in creating advanced luminescent materials is identifying optimal synthesis techniques to produce samples with high efficiency. To address this, various preparation methods have been developed, including solid-state reactions, hydrothermal synthesis, sol–gel processing, and template-directed methods etc. Other techniques include solvothermal-mediated microemulsions, as well as combining reverse micelle systems with dip-coating technology. [6–7]. Suitable organic-inorganic ligands can be used to tune the size and shape of the nanoparticles but long chain organic ligands cause quenching of luminescence due to high energy vibrations of the ligands. Long chain hydrocarbons such as oleic acid, AOT, SDS etc. are not preferred as because they contain a number of O-H and C-H groups. Vibration of these groups lead to absorption of exciting light and non-radiative process occurs instead of radiative process. Synthetic methods employing high temperature could lead to agglomerated nanoparticles. This may cause decrease in luminescence intensity due to cross relaxation among Ln 3+ ions. Therefore, in order to overcome the limitations encountered in these synthetic routes, efforts have been made to synthesize efficient phosphors with high luminescence intensity employing low temperature synthesis. When SrWO 4 are doped with lanthanide ions (Eu 3+ , Tb 3+ ), they show their characteristic narrow red, green, and blue emissions and therefore these materials could serve as efficient phosphors in light emitting diode (LEDs) and other optical devices. In the present work, SrWO 4 : Eu 3+ , SrWO 4 : Tb 3+ are prepared using ethylene glycol (EG) as the reaction medium; it also serves as the capping agent following the same reaction conditions as reported in my earlier works [8–12]. The luminescent properties of the synthesized nanoparticles are also studied in the present work. 2. Experimental details 2.1 Sample preparation Nanoparticles of SrWO 4 doped with different RE 3+ ions (Eu 3+ , Tb 3+ ) were prepared using ethylene glycol as both capping agent and reaction medium and the temperature was maintained at 130 o C. Strontium nitrate (Sr(NO 3 ) 2 ), europium oxide (Eu 2 O 3 ,99.99%, Aldrich), terbium nitrate hexahydrate (Tb(NO 3 ) 3 .6H 2 O, 99.99%, Aldrich), and sodium tungstate dihydrate (Na 2 WO 4 .2H 2 O, AR) were used as sources of Ca 2+ , Eu 3+ , Tb 3+ and WO 4 2− , respectively. Similar synthesis procedure was followed to prepare all the RE 3+ doped samples by taking stoichiometric amounts of the starting materials as described in my earlier works. The dried as prepared sample was then used for further characterization and luminescence studies. 2.2 Characterization X-ray powder diffraction (XRD) data for all the samples were recorded using PANalytical powder diffractometer (X Pert PRO) with CuKα (1.5405 angstrom) radiation with Ni filter. The surface morphology of the samples was studied using CM-200 TEM (transmission electron microscopy). Infrared spectra were recorded on a Fourier transform infrared (FT-IR) spectrophotometer of Shimadzu (model 8400S) using thin pellets with KBr. UV-vis absorption spectrum was measured on Shimadzu (model 2450) spectrophotometer. All the photoluminescence spectra and lifetime measurements of the samples were recorded using Perkin Elmer (LS-55) luminescence spectrometer in phosphorescence mode with xenon discharge lamp as the excitation source having pulse width at half height < 10 µs. 3. Results and Discussion 3.1 XRD study Figure 1 shows the XRD patterns of SrWO4 doped with different rare earth ions. The pattern shows well defined peaks and all these peaks could be indexed to the tetragonal phase of SrWO 4 with JCPDS card No. 01-085-0587 [13]. These powder phosphors fundamentally maintain characteristics of a scheelite structure which obviously are not affected by doped RE 3+ ions [14]. The highest intensity peak is visible at 2θ ≈ 27 o (1 1 2). Figure 1 does not show any differences regarding scheelite diffraction patterns which indicate that doped RE 3+ ions do not change the lattice structure. Due to different valence states and the difference in the ion size between W 6+ (0.042 nm) and RE 3+ , RE 3+ are expected to occupy the Sr 2+ (0.113 nm) site in this phosphor [15] which is reasonable because the electronic densities of RE 3+ and Sr 2+ at their coordination numbers are analogous [16]. No additional peaks for other phases have been found in all the patterns and this absence is strong verification of successful substitution of Sr 2+ by the RE 3+ ions in the tungstate framework. The mean particle size of SrWO 4 :RE 3+ can be roughly determined from the broadening of peaks by using the Scherrer formula: d = 0.9λ/βcosθ , where λ is the wavelength of the X-ray and β is the full width at half maximum (FWHM). For Eu 3+ and Tb 3+ doped samples, mean particle sizes are found to be 17 and 18 nm, respectively. The unit cell volume can be determined by calculating the cell parameters. The lattice parameters for 5 at. % Eu 3+ is found to be a = 5.414, c = 11.96 and V = 350.564 and that for 15 at. % Tb 3+ is a = 5.418, c = 11.90 and V = 349.321. 3.2 TEM study Figure 2 shows the TEM images of Tb 3+ and Eu 3+ doped SrWO 4 nanoparticles. The majority of Tb 3+ doped samples are spherical shaped (Fig. 2 a), and the sizes are in the range of 15–23 nm in diameter. In addition to these, somewhat larger particles could also be seen. Eu 3+ doped samples have particle size in the range of 21–30 nm; they do not have a regular shape; some are spherical while some are cubical (Fig. 2 b). 3.3 FT-IR study Figure 3 shows the FT-IR spectra for Eu 3+ and Tb 3+ doped SrWO 4 nanoparticles. The FT-IR spectrum shows prominent bands at around 3300, 2853, 2890, 2924, 1383, 1650, 820 and 430–440 cm − 1 . The bands at 1650 and 3300 cm − 1 correspond to H–O–H bending and O–H stretching vibrations of water molecules present on the surface of nanoparticles, respectively [17]. The band at 820 cm − 1 is due to the O–W–O asymmetric stretching vibration of the WO 4 2− tetrahedron and 440 cm − 1 corresponds to the stretching vibration of W–O [18]. 1383 cm − 1 vibration is due to the N–O band from HNO 3 used in the sample preparation. In the as-prepared sample peaks are observed at 2853 and 2924 cm − 1 indicating C–H stretching vibration from EG molecules on the surface of SrWO 4 :RE 3+ nanoparticles. 3.4 Luminescence study Figure 4 a-b showed the excitation and emission spectra of SrWO 4 : Tb 3+ (7 at. %) nanoparticles prepared in EG. The excitation spectra were obtained by monitoring the emission of the Tb 3+ 5 D 4 - 7 F 5 transition at 546 nm. The excitation spectrum shows a broad band from 230 to 350 nm with its peak maximum at 238 nm. This peak maximum corresponds to oxygen-to-metal charge transfer (CTB) in tungstate [19]. This arises from the transition of 2 p electrons of O 2− to the empty 5 d shells of W 6+ ions in the WO 4 2− group. Other bands observed from 350–450 nm are due to f-f transitions of rare-earth ions [20]. These peaks are weak compared to charge-transfer as f-f transitions are forbidden in nature. The presence of the excitation band of the WO 4 2− groups in the excitation spectrum of Tb 3+ indicates that there is an energy transfer from the WO 4 2− groups to Tb 3+ ions in the SrWO 4 :Tb 3+ nanoparticles. Upon excitation into the WO 4 2− at 238 nm, the obtained emission spectrum contains the characteristic emission of Tb 3+ with 5 D 4 - 7 F 5 green emission (546 nm) as the most prominent group. In addition to this, some weaker emissions could also be observed and are located at 439, 491, 590 and 621 nm and they have been attributed to the transitions of 5 D 3 → 7 F 4 , 5 D 4 → 7 F 6 , 5 D 4 → 7 F 4 and 5 D 4 → 7 F 3 , respectively. The emission spectra shows that the luminescence intensity increases as the Tb 3+ ion concentration is increased from 2 to 7 at. % and beyond this concentration, luminescence intensity decreases drastically. Thus, we can say that the optimum Tb 3+ concentration for maximum luminescent intensity is 7 at. %. Above this particular concentration, the emission intensity decreases and this is due to concentration quenching effect. There is an increase in the dipole-dipole interaction with the increase in Tb 3+ ion concentration eventually the cross- relaxation among Tb 3+ ions increases when the mean distance between them is less than a critical value. Similarly, for Eu 3+ doped samples, the excitation spectrum (Fig. 5 a-b) consists of a broad band at around 240 nm which can be attributed to the charge transfer within the WO 4 2− group [40–42]. Other weak peaks from 350–450 nm are also observed which may be due to f-f transitions of Eu 3+ ion. Figure 5 (a) shows the emission spectra for different concentrations of Eu 3+ doped SrWO 4 samples. In the emission spectra, two prominent peaks are located at 595 nm (orange region) and 615 nm (red region). The 595 peak arises due to 5 D 1 - 7 F 1 transition and 615 nm is due to 5 D 0 - 7 F 2 transition. The electric dipole transition which is red in colour is dominant over orange transition. From Fig. 5 (b), it is also evident that the luminescence intensity varies with change in Eu 3+ ion concentration. The intensity increases gradually with increase in rare-earth concentration from 5 at. % to 7 at. %, and further increases with up to 10 at. % of Eu 3+ but beyond this concentration, the luminescence intensity decreases sharply. This phenomenon is due to the concentration quenching when the mean distance between the Eu 3+ -Eu 3+ is less than a critical value due to increased Eu 3+ ion concentration. Thus, the optimum concentration for Eu 3+ ion in SrWO 4 for highest intensity is 10 at. %. This decrease in luminescence intensity after reaching a certain concentration of RE 3+ is due to the quenching effect where reduced distance between activator ions increases nonradiative energy transfer [21]. Higher dopant ion concentration is not always favourable for phosphors and the need for knowing the optimum concentration of the dopant ion increases. 4. Conclusion SrWO 4 :RE 3+ (RE = Eu, Tb) phosphors are prepared using ethylene glycol route. The synthesized samples possess a highly crystalline tetragonal structure. The size of the particles as determined from XRD study is around 20 nm. The shape of the prepared nanoparticles as seen from TEM images show that Tb 3+ doped samples have spherical shape, Eu 3+ are cubically as well as spherically shaped and the nanoparticles are well crystalline. FT-IR study shows bands at 820 cm − 1 (which is due to the O–W–O asymmetric stretching vibration of the WO 4 2− tetrahedron) and 440 cm − 1 (corresponding to the stretching vibration of W–O). From the excitation spectra, it is found that a broad band occurs from 230–350 nm with peak maximum at around 240 nm. This peak maximum corresponds to oxygen-to-metal charge transfer (CTB) in WO 4 2− . This arises from the transition of 2 p electrons of O 2− to the empty 5 d shells of W 6+ ions in the WO 4 2− group. Other weaker bands observed from 350–450 nm are due to f-f transitions of rare-earth ions. These peaks are weak compared to charge-transfer as f-f transitions are forbidden in nature. For Eu 3+ doped samples, characteristic emission lines are observed at 595 nm and 614 nm due to 5 D 1 - 7 F 1 and 5 D 0 - 7 F 2 transitions respectively; for Tb 3+ doped samples, characteristic green emission could be observed at 546 nm due to 5 D 4 - 7 F 5 transition. The luminescence intensity is again greatly influenced by the doping concentrations of the lanthanide ion, though no shift has been observed towards the higher or lower wavelength region by varying the doping concentration of dopant ion. For Eu 3+ doped samples, the optimum concentration is found to be 10 at. %; for Tb 3+ doped samples, the highest luminescence intensity is found to be 7 at. %. Declarations Ethica approval and consent to participate Not applicable. Competing interests The authors declare no competing interests. Funding This research received no external funding. Author Contribution Dr. Kongbrailatpam Gayatri Sharma: Manuscript writing and reviewing, analysis and planning. Acknowledgement I acknowledge Dr. Th. Prasanta Singh, Chemistry Department, Standard College, Imphal, Manipur for reviewing the manuscript. Data Availability Data cannot be shared openly, but is available on request from the author. References Kazenas EK, Andreeva NA, Astakhova GK, Volchenkova VA, Ovchinnikova OA, Penkina TN, Fomina ON. Vapor composition and thermodynamic characteristics of gaseous molecules of alkaline earth metal tungstates. Inorg Mater Appl Res. 2024;15:893. https://doi.org/10.1134/S2075113324700357 . Hota SS, Panda D, Choudhary RNP. Studies of structural, dielectric, and electrical properties of polycrystalline barium bismuth tungstate for thermistor application. Inorg Chem Commun. 2023;153:110785. https://doi.org/10.1016/j.inoche.2023.110785 . Thongtem T, Kungwankunakorn S, Kuntalue B, Phuruangrat A, Thongtem S. Luminescence and absorbance of highly crystalline CaMoO 4 , SrMoO 4 , CaWO 4 and SrWO 4 nanoparticles synthesized by co-precipitation method at room temperature. J Alloys Compd. 2010;506:475. https://doi.org/10.1016/j.jallcom.2010.07.033 . Pereira PFS, Nogueira IC, Longo E, Nassar EJ, Rosa ILV, Cavalcante LS. Rietveld refinement and optical properties of SrWO 4 :Eu 3+ powders prepared by the non-hydrolytic sol-gel method. J Rare Earths. 2015;33:113. https://doi.org/10.1016/S1002-0721(14)60391-4 . Maheshwary, Singh BP, Singh RA. Effect of annealing on the structural, optical and emissive properties of SrWO 4 :Ln 3+ (Dy 3+ , Eu 3+ and Sm 3+ ). Nanopart Spectrochim Acta Mol Biomol Spectrosc. 2016;152:199. https://doi.org/10.1016/j.saa.2015.07.074 . Zheng Y, Lin X, Wang Q, Cai W, Zhang CC. Dibenzoyl-L-cystine as organic directing agent for assembly of visible-light-sensitized luminescent AgGd (MoO 4 ) 2 : Eu 3+ nanowires. Mat Res Bull. 2012;47(3):856. https://doi.org/10.1016/j.materresbull.2011.11.045 . Kumari S, Rao AS, Sinha RK. Structural and photoluminescence properties of Sm 3+ ions doped strontium yttrium tungstate phosphors for reddish-orange photonic device applications. Mat Res Bull. 2023;167:112419. https://doi.org/10.1016/j.materresbull.2023.112419 . Sharma KG, Singh NR. Synthesis of CaWO 4 :Eu 3+ phosphor powders via ethylene glycol route and its optical properties. J Rare Earths. 2012;30:310. https://doi.org/10.1016/S1002-0721(12)60043-X . Sharma KG, Singh NR. Re-dispersible CaWO 4 :Tb 3+ nanoparticles: Synthesis, characterization and photoluminescence studies. J Lumin. 2013;139:98. https://doi.org/10.1016/j.jlumin.2013.02.006 . Sharma KG, Singh NR. Synthesis and luminescence properties of CaMO 4 :Dy 3+ (M = W, Mo) nanoparticles prepared via an ethylene glycol route. New J Chem. 2013;37:2784. https://doi.org/10.1039/C3NJ00155E . Sharma KG, Singh TP, Singh NR. Low temperature synthesis, characterization and tunable optical properties of Eu 3+ , Tb 3+ doped CaMoO 4 nanoparticles. J Alloys Compd. 2014;602:275. https://doi.org/10.1016/j.jallcom.2014.02.186 . Sharma KG, Singh NS, Devi YR, Singh NR, Singh SD. Effects of annealing on luminescence of CaWO 4 : Eu 3+ nanoparticles and its thermoluminescence study. J Alloys Compd. 2013;556:94. https://doi.org/10.1016/j.jallcom.2012.12.087 . Potanina EA, Orlova AI, Mikhailov DA, Nokhrin AV, Chuvil'deev VN, Boldin MS, Sakharov NV, Lantcev EA, Tokarev MG, Murashov AA. Spark plasma sintering of fine-grained SrWO 4 and NaNd(WO 4 ) 2 tungstates ceramics with the scheelite structure for nuclear waste immobilization. J Alloys Compd. 2019;774:182. https://doi.org/10.1016/j.jallcom.2018.09.348 . Zhou L, Wei J, Wu J, Gong F, Yi L, Huang J. Potential red-emitting phosphor for white LED solid-state lighting. J Alloys Compd. 2009;476:390. https://doi.org/10.1016/j.jallcom.2008.09.005 . He X, Guan M, Lian N, Sun J, Shang T. Synthesis and luminescence characteristics of K 2 Bi (PO 4 )(MO 4 ): Eu 3+ (M = Mo, W) red-emitting phosphor for white LEDs. J Alloys Compd. 2010;492:452. https://doi.org/10.1016/j.jallcom.2009.11.138 . Sivaganesh D, Saravanakumar S, Sivakumar V, Sasikumar S, Gopal JN, Kalpana S, Rajajeyaganthan R. Sm 3+ induced-SrWO 4 phosphor: analysis of photoluminescence and photocatalytic properties with electron density distribution studies. J Mater Sci: Mater Electron. 2020;31:8865. https://doi.org/10.1007/s10854-020-03421-8 . Seki T, Chiang KY, Yu CC, Yu X, Okuno M, Hunger J, Nagata Y, Bonn M. The bending mode of water: a powerful probe for hydrogen bond structure of aqueous systems. J Phys Chem Lett. 2020;11:8459. https://doi.org/10.1021/acs.jpclett.0c01259 . Azevêdo HV, da Silva EBS, Fernandes RS, Albuquerque AR, Gomes UU, Cavalcante DG. Green chemistry synthesis of wolframites: An investigation about stoichiometric ratios, optical, structural, vibrational, and physico-chemical properties. J Clean Prod. 2023;385:35528. https://doi.org/10.1016/j.jclepro.2022.135528 . Alexander D, Kumar BR, Mathews JM. Spectroscopic analysis of calcium tungstate and Eu doped calcium tungstate phosphor. Mater Today Proc. 2023. https://doi.org/10.1016/j.matpr.2023.11.129 Hasegawa M, Ohmagari H, Tanaka H, Machida K. Luminescence of lanthanide complexes: From fundamental to prospective approaches related to water-and molecular-stimuli. J Photochem Photobiol C Photochem Rev.2022;50: 100484.https://doi.org/10.1016/j.jphotochemrev.2022.100484 Sun L, Gao R, Pan T, Ai XC, Fu L, Zhang JP. Concentration-regulated photon upconversion and quenching in NaYF 4 : Yb 3+ , Er 3+ nanocrystals: nonexponentiality revisited. Nanoscale. 2019;11:18150. https://doi.org/10.1039/C9NR06521K . Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Revision Version 1 posted Editorial decision: Revision requested 06 May, 2026 Reviews received at journal 12 Apr, 2026 Reviews received at journal 06 Apr, 2026 Reviews received at journal 06 Apr, 2026 Reviews received at journal 05 Apr, 2026 Reviewers agreed at journal 31 Mar, 2026 Reviewers agreed at journal 31 Mar, 2026 Reviewers agreed at journal 29 Mar, 2026 Reviewers agreed at journal 29 Mar, 2026 Reviewers invited by journal 29 Mar, 2026 Editor invited by journal 24 Mar, 2026 Editor assigned by journal 20 Mar, 2026 Submission checks completed at journal 20 Mar, 2026 First submitted to journal 17 Mar, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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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-9151142","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":615441874,"identity":"1dd24f00-0d53-4bb7-b0c5-e2a74fa55ec3","order_by":0,"name":"Kongbrailatpam Gayatri 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16:39:03","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9151142/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9151142/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":105996616,"identity":"7bc50f57-3ae7-4838-8b6b-7d61cdb692d3","added_by":"auto","created_at":"2026-04-02 09:18:54","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":18835,"visible":true,"origin":"","legend":"\u003cp\u003eXRD patterns of RE\u003csup\u003e3+\u003c/sup\u003e doped SrWO\u003csub\u003e4\u003c/sub\u003e nanoparticles.\u003c/p\u003e","description":"","filename":"1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9151142/v1/de6113b3b344be1dd2e6cb0b.jpg"},{"id":105996617,"identity":"45ae9da7-f38e-40d1-81b5-0a4e137a0e92","added_by":"auto","created_at":"2026-04-02 09:18:54","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":38410,"visible":true,"origin":"","legend":"\u003cp\u003eTEM images of (a) 7 at. % Tb\u003csup\u003e3+\u003c/sup\u003e and (b) 5 at. % Eu\u003csup\u003e3+\u003c/sup\u003e.\u003c/p\u003e","description":"","filename":"2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9151142/v1/3a654ea3f4ce596993b8d13c.jpg"},{"id":106094599,"identity":"7e16fb14-55cf-4e02-b71b-33dd8f86b37e","added_by":"auto","created_at":"2026-04-03 11:42:57","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":29404,"visible":true,"origin":"","legend":"\u003cp\u003eFT-IR spectra for (a) 5 at. % Eu\u003csup\u003e3+\u003c/sup\u003e and (b) 7 at. % Tb\u003csup\u003e3+\u003c/sup\u003e doped SrWO\u003csub\u003e4\u003c/sub\u003e nanoparticles.\u003c/p\u003e","description":"","filename":"3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9151142/v1/b4bbf1d3cfee4f1eb1e7cf87.jpg"},{"id":105996618,"identity":"18fdd608-e5a0-4091-a3f1-f41438ac8082","added_by":"auto","created_at":"2026-04-02 09:18:54","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":26012,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Excitation and (b) emission spectra for SrWO\u003csub\u003e4\u003c/sub\u003e:Tb\u003csup\u003e3+\u003c/sup\u003e nanoparticles prepared in EG.\u003c/p\u003e","description":"","filename":"4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9151142/v1/2bb0d12f2e62ea68238c83d0.jpg"},{"id":105996620,"identity":"5d93879c-e115-4098-bca5-b2be0a4e28a3","added_by":"auto","created_at":"2026-04-02 09:18:54","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":47751,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Excitation and (b) emission spectra of SrWO\u003csub\u003e4\u003c/sub\u003e:Eu\u003csup\u003e3+\u003c/sup\u003e nanoparticles in EG.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-9151142/v1/ebbdb974c78c2ee3289ddbb0.png"},{"id":106095835,"identity":"24d1ba75-cd1a-4b42-8f19-5cd41bada5d6","added_by":"auto","created_at":"2026-04-03 11:51:18","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":680367,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9151142/v1/15a9ff94-f42c-403f-b976-ac84beb39c59.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Photoluminescent properties of Eu 3+ , Tb 3+ doped SrWO 4 nanoparticles prepared by ethylene glycol route","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eAlkaline-earth-metal tungstates AWO\u003csub\u003e4\u003c/sub\u003e (A\u0026thinsp;=\u0026thinsp;Ca, Sr, Ba) form a significant family of scheelite-type inorganic materials which are recognized for their structural stability and versatile optoelectronic properties [1\u0026ndash;2]; showing wide applications in thermoluminescence, lasers and as excellent host material. Out of these alkaline-earth tungstates, SrWO\u003csub\u003e4\u003c/sub\u003e is an important electro-optical material which has an intrinsic strong blue emission band; however, its luminescence covers a broad range of wavelengths that are insensitive to external changes [3].\u003c/p\u003e \u003cp\u003eOver the past few decades, the luminescent properties of rare-earth ions have been the subject of extensive research due to their unique electronic configurations, specifically the rich energy level structures within the 4f orbitals, rare-earth materials exhibit diverse and abundant emission spectra [4]. Lanthanide-activated (Eu\u0026sup3;⁺, Tb\u0026sup3;⁺, Sm\u0026sup3;⁺, and Dy\u0026sup3;⁺) SrWO₄ phosphors are reported to produce sharp, characteristic red, green, and blue emissions, making them promising candidates for efficient LED and optical device applications. [5].\u003c/p\u003e \u003cp\u003eA major challenge in creating advanced luminescent materials is identifying optimal synthesis techniques to produce samples with high efficiency. To address this, various preparation methods have been developed, including solid-state reactions, hydrothermal synthesis, sol\u0026ndash;gel processing, and template-directed methods etc. Other techniques include solvothermal-mediated microemulsions, as well as combining reverse micelle systems with dip-coating technology. [6\u0026ndash;7]. Suitable organic-inorganic ligands can be used to tune the size and shape of the nanoparticles but long chain organic ligands cause quenching of luminescence due to high energy vibrations of the ligands. Long chain hydrocarbons such as oleic acid, AOT, SDS etc. are not preferred as because they contain a number of O-H and C-H groups. Vibration of these groups lead to absorption of exciting light and non-radiative process occurs instead of radiative process. Synthetic methods employing high temperature could lead to agglomerated nanoparticles. This may cause decrease in luminescence intensity due to cross relaxation among Ln\u003csup\u003e3+\u003c/sup\u003e ions. Therefore, in order to overcome the limitations encountered in these synthetic routes, efforts have been made to synthesize efficient phosphors with high luminescence intensity employing low temperature synthesis. When SrWO\u003csub\u003e4\u003c/sub\u003e are doped with lanthanide ions (Eu\u003csup\u003e3+\u003c/sup\u003e, Tb\u003csup\u003e3+\u003c/sup\u003e), they show their characteristic narrow red, green, and blue emissions and therefore these materials could serve as efficient phosphors in light emitting diode (LEDs) and other optical devices.\u003c/p\u003e \u003cp\u003eIn the present work, SrWO\u003csub\u003e4\u003c/sub\u003e: Eu\u003csup\u003e3+\u003c/sup\u003e, SrWO\u003csub\u003e4\u003c/sub\u003e: Tb\u003csup\u003e3+\u003c/sup\u003e are prepared using ethylene glycol (EG) as the reaction medium; it also serves as the capping agent following the same reaction conditions as reported in my earlier works [8\u0026ndash;12]. The luminescent properties of the synthesized nanoparticles are also studied in the present work.\u003c/p\u003e"},{"header":"2. Experimental details","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Sample preparation\u003c/h2\u003e \u003cp\u003eNanoparticles of SrWO\u003csub\u003e4\u003c/sub\u003e doped with different RE\u003csup\u003e3+\u003c/sup\u003e ions (Eu\u003csup\u003e3+\u003c/sup\u003e, Tb\u003csup\u003e3+\u003c/sup\u003e) were prepared using ethylene glycol as both capping agent and reaction medium and the temperature was maintained at 130 \u003csup\u003eo\u003c/sup\u003eC. Strontium nitrate (Sr(NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e), europium oxide (Eu\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e,99.99%, Aldrich), terbium nitrate hexahydrate (Tb(NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e.6H\u003csub\u003e2\u003c/sub\u003eO, 99.99%, Aldrich), and sodium tungstate dihydrate (Na\u003csub\u003e2\u003c/sub\u003eWO\u003csub\u003e4\u003c/sub\u003e.2H\u003csub\u003e2\u003c/sub\u003eO, AR) were used as sources of Ca\u003csup\u003e2+\u003c/sup\u003e, Eu\u003csup\u003e3+\u003c/sup\u003e, Tb\u003csup\u003e3+\u003c/sup\u003eand WO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e, respectively. Similar synthesis procedure was followed to prepare all the RE\u003csup\u003e3+\u003c/sup\u003e doped samples by taking stoichiometric amounts of the starting materials as described in my earlier works.\u003c/p\u003e \u003cp\u003eThe dried as prepared sample was then used for further characterization and luminescence studies.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Characterization\u003c/h2\u003e \u003cp\u003eX-ray powder diffraction (XRD) data for all the samples were recorded using PANalytical powder diffractometer (X Pert PRO) with CuKα (1.5405 angstrom) radiation with Ni filter. The surface morphology of the samples was studied using CM-200 TEM (transmission electron microscopy). Infrared spectra were recorded on a Fourier transform infrared (FT-IR) spectrophotometer of Shimadzu (model 8400S) using thin pellets with KBr. UV-vis absorption spectrum was measured on Shimadzu (model 2450) spectrophotometer. All the photoluminescence spectra and lifetime measurements of the samples were recorded using Perkin Elmer (LS-55) luminescence spectrometer in phosphorescence mode with xenon discharge lamp as the excitation source having pulse width at half height\u0026thinsp;\u0026lt;\u0026thinsp;10 \u0026micro;s.\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results and Discussion","content":"\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\n\u003ch2\u003e3.1 XRD study\u003c/h2\u003e\n\u003cp\u003eFigure\u0026nbsp;1 shows the XRD patterns of SrWO4 doped with different rare earth ions. The pattern shows well defined peaks and all these peaks could be indexed to the tetragonal phase of SrWO\u003csub\u003e4\u003c/sub\u003e with JCPDS card No. 01-085-0587 [13].\u003c/p\u003e\n\u003cp\u003eThese powder phosphors fundamentally maintain characteristics of a scheelite structure which obviously are not affected by doped RE\u003csup\u003e3+\u003c/sup\u003e ions [14]. The highest intensity peak is visible at 2\u0026theta;\u0026thinsp;\u0026asymp;\u0026thinsp;27\u003csup\u003eo\u003c/sup\u003e (1 1 2). Figure\u0026nbsp;1 does not show any differences regarding scheelite diffraction patterns which indicate that doped RE\u003csup\u003e3+\u003c/sup\u003e ions do not change the lattice structure. Due to different valence states and the difference in the ion size between W\u003csup\u003e6+\u003c/sup\u003e (0.042 nm) and RE\u003csup\u003e3+\u003c/sup\u003e, RE\u003csup\u003e3+\u003c/sup\u003e are expected to occupy the Sr\u003csup\u003e2+\u003c/sup\u003e (0.113 nm) site in this phosphor [15] which is reasonable because the electronic densities of RE\u003csup\u003e3+\u003c/sup\u003e and Sr\u003csup\u003e2+\u003c/sup\u003e at their coordination numbers are analogous [16]. No additional peaks for other phases have been found in all the patterns and this absence is strong verification of successful substitution of Sr\u003csup\u003e2+\u003c/sup\u003e by the RE\u003csup\u003e3+\u003c/sup\u003e ions in the tungstate framework.\u003c/p\u003e\n\u003cp\u003eThe mean particle size of SrWO\u003csub\u003e4\u003c/sub\u003e:RE\u003csup\u003e3+\u003c/sup\u003e can be roughly determined from the broadening of peaks by using the Scherrer formula:\u003c/p\u003e\n\u003cp\u003e\u003cem\u003ed\u0026thinsp;=\u0026thinsp;0.9\u0026lambda;/\u0026beta;cos\u0026theta;\u003c/em\u003e,\u003c/p\u003e\n\u003cp\u003ewhere \u003cem\u003e\u0026lambda;\u003c/em\u003e is the wavelength of the X-ray and \u003cem\u003e\u0026beta;\u003c/em\u003e is the full width at half maximum (FWHM).\u003c/p\u003e\n\u003cp\u003eFor Eu\u003csup\u003e3+\u003c/sup\u003e and Tb\u003csup\u003e3+\u003c/sup\u003e doped samples, mean particle sizes are found to be 17 and 18 nm, respectively. The unit cell volume can be determined by calculating the cell parameters. The lattice parameters for 5 at. % Eu\u003csup\u003e3+\u003c/sup\u003e is found to be \u003cem\u003ea\u003c/em\u003e\u0026thinsp;=\u0026thinsp;5.414, \u003cem\u003ec\u003c/em\u003e\u0026thinsp;=\u0026thinsp;11.96 and V\u0026thinsp;=\u0026thinsp;350.564 and that for 15 at. % Tb\u003csup\u003e3+\u003c/sup\u003e is \u003cem\u003ea\u003c/em\u003e\u0026thinsp;=\u0026thinsp;5.418, \u003cem\u003ec\u003c/em\u003e\u0026thinsp;=\u0026thinsp;11.90 and V\u0026thinsp;=\u0026thinsp;349.321.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\n\u003ch2\u003e3.2 TEM study\u003c/h2\u003e\n\u003cp\u003eFigure\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e shows the TEM images of Tb\u003csup\u003e3+\u003c/sup\u003e and Eu\u003csup\u003e3+\u003c/sup\u003e doped SrWO\u003csub\u003e4\u003c/sub\u003e nanoparticles. The majority of Tb\u003csup\u003e3+\u003c/sup\u003e doped samples are spherical shaped (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ea), and the sizes are in the range of 15\u0026ndash;23 nm in diameter. In addition to these, somewhat larger particles could also be seen. Eu\u003csup\u003e3+\u003c/sup\u003e doped samples have particle size in the range of 21\u0026ndash;30 nm; they do not have a regular shape; some are spherical while some are cubical (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003eb).\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\n\u003ch2\u003e3.3 FT-IR study\u003c/h2\u003e\n\u003cp\u003eFigure\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e shows the FT-IR spectra for Eu\u003csup\u003e3+\u003c/sup\u003e and Tb\u003csup\u003e3+\u003c/sup\u003e doped SrWO\u003csub\u003e4\u003c/sub\u003e nanoparticles. The FT-IR spectrum shows prominent bands at around 3300, 2853, 2890, 2924, 1383, 1650, 820 and 430\u0026ndash;440 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003eThe bands at 1650 and 3300 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e correspond to H\u0026ndash;O\u0026ndash;H bending and O\u0026ndash;H stretching vibrations of water molecules present on the surface of nanoparticles, respectively [17].\u003c/p\u003e\n\u003cp\u003eThe band at 820 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is due to the O\u0026ndash;W\u0026ndash;O asymmetric stretching vibration of the WO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e tetrahedron and 440 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e corresponds to the stretching vibration of W\u0026ndash;O [18]. 1383 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e vibration is due to the N\u0026ndash;O band from HNO\u003csub\u003e3\u003c/sub\u003e used in the sample preparation. In the as-prepared sample peaks are observed at 2853 and 2924 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e indicating C\u0026ndash;H stretching vibration from EG molecules on the surface of SrWO\u003csub\u003e4\u003c/sub\u003e:RE\u003csup\u003e3+\u003c/sup\u003e nanoparticles.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e\n\u003ch2\u003e3.4 Luminescence study\u003c/h2\u003e\n\u003cp\u003eFigure\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003ea-b showed the excitation and emission spectra of SrWO\u003csub\u003e4\u003c/sub\u003e: Tb\u003csup\u003e3+\u003c/sup\u003e (7 at. %) nanoparticles prepared in EG. The excitation spectra were obtained by monitoring the emission of the Tb\u003csup\u003e3+ 5\u003c/sup\u003eD\u003csub\u003e4\u003c/sub\u003e-\u003csup\u003e7\u003c/sup\u003eF\u003csub\u003e5\u003c/sub\u003e transition at 546 nm. The excitation spectrum shows a broad band from 230 to 350 nm with its peak maximum at 238 nm. This peak maximum corresponds to oxygen-to-metal charge transfer (CTB) in tungstate [19]. This arises from the transition of 2\u003cem\u003ep\u003c/em\u003e electrons of O\u003csup\u003e2\u0026minus;\u003c/sup\u003e to the empty 5\u003cem\u003ed\u003c/em\u003e shells of W\u003csup\u003e6+\u003c/sup\u003e ions in the WO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e group. Other bands observed from 350\u0026ndash;450 nm are due to \u003cem\u003ef-f\u003c/em\u003e transitions of rare-earth ions [20]. These peaks are weak compared to charge-transfer as \u003cem\u003ef-f\u003c/em\u003e transitions are forbidden in nature.\u003c/p\u003e\n\u003cp\u003eThe presence of the excitation band of the WO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e groups in the excitation spectrum of Tb\u003csup\u003e3+\u003c/sup\u003e indicates that there is an energy transfer from the WO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e groups to Tb\u003csup\u003e3+\u003c/sup\u003e ions in the SrWO\u003csub\u003e4\u003c/sub\u003e:Tb\u003csup\u003e3+\u003c/sup\u003e nanoparticles. Upon excitation into the WO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e at 238 nm, the obtained emission spectrum contains the characteristic emission of Tb\u003csup\u003e3+\u003c/sup\u003e with \u003csup\u003e5\u003c/sup\u003eD\u003csub\u003e4\u003c/sub\u003e-\u003csup\u003e7\u003c/sup\u003eF\u003csub\u003e5\u003c/sub\u003e green emission (546 nm) as the most prominent group. In addition to this, some weaker emissions could also be observed and are located at 439, 491, 590 and 621 nm and they have been attributed to the transitions of \u003csup\u003e5\u003c/sup\u003eD\u003csub\u003e3\u003c/sub\u003e\u0026rarr;\u003csup\u003e7\u003c/sup\u003eF\u003csub\u003e4\u003c/sub\u003e, \u003csup\u003e5\u003c/sup\u003eD\u003csub\u003e4\u003c/sub\u003e\u0026rarr;\u003csup\u003e7\u003c/sup\u003eF\u003csub\u003e6\u003c/sub\u003e, \u003csup\u003e5\u003c/sup\u003eD\u003csub\u003e4\u003c/sub\u003e\u0026rarr;\u003csup\u003e7\u003c/sup\u003eF\u003csub\u003e4\u003c/sub\u003e and \u003csup\u003e5\u003c/sup\u003eD\u003csub\u003e4\u003c/sub\u003e\u0026rarr;\u003csup\u003e7\u003c/sup\u003eF\u003csub\u003e3\u003c/sub\u003e, respectively.\u003c/p\u003e\n\u003cp\u003eThe emission spectra shows that the luminescence intensity increases as the Tb\u003csup\u003e3+\u003c/sup\u003e ion concentration is increased from 2 to 7 at. % and beyond this concentration, luminescence intensity decreases drastically. Thus, we can say that the optimum Tb\u003csup\u003e3+\u003c/sup\u003e concentration for maximum luminescent intensity is 7 at. %. Above this particular concentration, the emission intensity decreases and this is due to concentration quenching effect. There is an increase in the dipole-dipole interaction with the increase in Tb\u003csup\u003e3+\u003c/sup\u003e ion concentration eventually the cross- relaxation among Tb\u003csup\u003e3+\u003c/sup\u003e ions increases when the mean distance between them is less than a critical value.\u003c/p\u003e\n\u003cp\u003eSimilarly, for Eu\u003csup\u003e3+\u003c/sup\u003e doped samples, the excitation spectrum (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003ea-b) consists of a broad band at around 240 nm which can be attributed to the charge transfer within the WO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e group [40\u0026ndash;42]. Other weak peaks from 350\u0026ndash;450 nm are also observed which may be due to \u003cem\u003ef-f\u003c/em\u003e transitions of Eu\u003csup\u003e3+\u003c/sup\u003e ion. Figure\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e(a) shows the emission spectra for different concentrations of Eu\u003csup\u003e3+\u003c/sup\u003e doped SrWO\u003csub\u003e4\u003c/sub\u003e samples. In the emission spectra, two prominent peaks are located at 595 nm (orange region) and 615 nm (red region). The 595 peak arises due to \u003csup\u003e5\u003c/sup\u003eD\u003csub\u003e1\u003c/sub\u003e-\u003csup\u003e7\u003c/sup\u003eF\u003csub\u003e1\u003c/sub\u003e transition and 615 nm is due to \u003csup\u003e5\u003c/sup\u003eD\u003csub\u003e0\u003c/sub\u003e-\u003csup\u003e7\u003c/sup\u003eF\u003csub\u003e2\u003c/sub\u003e transition. The electric dipole transition which is red in colour is dominant over orange transition.\u003c/p\u003e\n\u003cp\u003eFrom Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e(b), it is also evident that the luminescence intensity varies with change in Eu\u003csup\u003e3+\u003c/sup\u003e ion concentration. The intensity increases gradually with increase in rare-earth concentration from 5 at. % to 7 at. %, and further increases with up to 10 at. % of Eu\u003csup\u003e3+\u003c/sup\u003e but beyond this concentration, the luminescence intensity decreases sharply. This phenomenon is due to the concentration quenching when the mean distance between the Eu\u003csup\u003e3+\u003c/sup\u003e-Eu\u003csup\u003e3+\u003c/sup\u003e is less than a critical value due to increased Eu\u003csup\u003e3+\u003c/sup\u003e ion concentration. Thus, the optimum concentration for Eu\u003csup\u003e3+\u003c/sup\u003e ion in SrWO\u003csub\u003e4\u003c/sub\u003e for highest intensity is 10 at. %.\u003c/p\u003e\n\u003cp\u003eThis decrease in luminescence intensity after reaching a certain concentration of RE\u003csup\u003e3+\u003c/sup\u003e is due to the quenching effect where reduced distance between activator ions increases nonradiative energy transfer [21]. Higher dopant ion concentration is not always favourable for phosphors and the need for knowing the optimum concentration of the dopant ion increases.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"4. Conclusion","content":"\u003cp\u003eSrWO\u003csub\u003e4\u003c/sub\u003e:RE\u003csup\u003e3+\u003c/sup\u003e (RE\u0026thinsp;=\u0026thinsp;Eu, Tb) phosphors are prepared using ethylene glycol route. The synthesized samples possess a highly crystalline tetragonal structure. The size of the particles as determined from XRD study is around 20 nm. The shape of the prepared nanoparticles as seen from TEM images show that Tb\u003csup\u003e3+\u003c/sup\u003e doped samples have spherical shape, Eu\u003csup\u003e3+\u003c/sup\u003e are cubically as well as spherically shaped and the nanoparticles are well crystalline. FT-IR study shows bands at 820 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (which is due to the O\u0026ndash;W\u0026ndash;O asymmetric stretching vibration of the WO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e tetrahedron) and 440 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (corresponding to the stretching vibration of W\u0026ndash;O). From the excitation spectra, it is found that a broad band occurs from 230\u0026ndash;350 nm with peak maximum at around 240 nm. This peak maximum corresponds to oxygen-to-metal charge transfer (CTB) in WO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e. This arises from the transition of 2\u003cem\u003ep\u003c/em\u003e electrons of O\u003csup\u003e2\u0026minus;\u003c/sup\u003e to the empty 5\u003cem\u003ed\u003c/em\u003e shells of W\u003csup\u003e6+\u003c/sup\u003e ions in the WO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e group. Other weaker bands observed from 350\u0026ndash;450 nm are due to \u003cem\u003ef-f\u003c/em\u003e transitions of rare-earth ions. These peaks are weak compared to charge-transfer as \u003cem\u003ef-f\u003c/em\u003e transitions are forbidden in nature. For Eu\u003csup\u003e3+\u003c/sup\u003e doped samples, characteristic emission lines are observed at 595 nm and 614 nm due to \u003csup\u003e5\u003c/sup\u003eD\u003csub\u003e1\u003c/sub\u003e-\u003csup\u003e7\u003c/sup\u003eF\u003csub\u003e1\u003c/sub\u003e and \u003csup\u003e5\u003c/sup\u003eD\u003csub\u003e0\u003c/sub\u003e-\u003csup\u003e7\u003c/sup\u003eF\u003csub\u003e2\u003c/sub\u003e transitions respectively; for Tb\u003csup\u003e3+\u003c/sup\u003e doped samples, characteristic green emission could be observed at 546 nm due to \u003csup\u003e5\u003c/sup\u003eD\u003csub\u003e4\u003c/sub\u003e-\u003csup\u003e7\u003c/sup\u003eF\u003csub\u003e5\u003c/sub\u003e transition. The luminescence intensity is again greatly influenced by the doping concentrations of the lanthanide ion, though no shift has been observed towards the higher or lower wavelength region by varying the doping concentration of dopant ion. For Eu\u003csup\u003e3+\u003c/sup\u003e doped samples, the optimum concentration is found to be 10 at. %; for Tb\u003csup\u003e3+\u003c/sup\u003e doped samples, the highest luminescence intensity is found to be 7 at. %.\u003c/p\u003e"},{"header":"Declarations","content":" \u003cp\u003e \u003cb\u003eEthica approval and consent to participate\u003c/b\u003e \u003c/p\u003e \u003cp\u003eNot applicable.\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eCompeting interests\u003c/strong\u003e \u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eThis research received no external funding.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eDr. Kongbrailatpam Gayatri Sharma: Manuscript writing and reviewing, analysis and planning.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eI acknowledge Dr. Th. Prasanta Singh, Chemistry Department, Standard College, Imphal, Manipur for reviewing the manuscript.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eData cannot be shared openly, but is available on request from the author.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eKazenas EK, Andreeva NA, Astakhova GK, Volchenkova VA, Ovchinnikova OA, Penkina TN, Fomina ON. Vapor composition and thermodynamic characteristics of gaseous molecules of alkaline earth metal tungstates. Inorg Mater Appl Res. 2024;15:893. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1134/S2075113324700357\u003c/span\u003e\u003cspan address=\"10.1134/S2075113324700357\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHota SS, Panda D, Choudhary RNP. Studies of structural, dielectric, and electrical properties of polycrystalline barium bismuth tungstate for thermistor application. Inorg Chem Commun. 2023;153:110785. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.inoche.2023.110785\u003c/span\u003e\u003cspan address=\"10.1016/j.inoche.2023.110785\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eThongtem T, Kungwankunakorn S, Kuntalue B, Phuruangrat A, Thongtem S. Luminescence and absorbance of highly crystalline CaMoO\u003csub\u003e4\u003c/sub\u003e, SrMoO\u003csub\u003e4\u003c/sub\u003e, CaWO\u003csub\u003e4\u003c/sub\u003e and SrWO\u003csub\u003e4\u003c/sub\u003e nanoparticles synthesized by co-precipitation method at room temperature. J Alloys Compd. 2010;506:475. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jallcom.2010.07.033\u003c/span\u003e\u003cspan address=\"10.1016/j.jallcom.2010.07.033\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePereira PFS, Nogueira IC, Longo E, Nassar EJ, Rosa ILV, Cavalcante LS. Rietveld refinement and optical properties of SrWO\u003csub\u003e4\u003c/sub\u003e:Eu\u003csup\u003e3+\u003c/sup\u003e powders prepared by the non-hydrolytic sol-gel method. J Rare Earths. 2015;33:113. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/S1002-0721(14)60391-4\u003c/span\u003e\u003cspan address=\"10.1016/S1002-0721(14)60391-4\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMaheshwary, Singh BP, Singh RA. Effect of annealing on the structural, optical and emissive properties of SrWO\u003csub\u003e4\u003c/sub\u003e:Ln\u003csup\u003e3+\u003c/sup\u003e (Dy\u003csup\u003e3+\u003c/sup\u003e, Eu\u003csup\u003e3+\u003c/sup\u003e and Sm\u003csup\u003e3+\u003c/sup\u003e). Nanopart Spectrochim Acta Mol Biomol Spectrosc. 2016;152:199. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.saa.2015.07.074\u003c/span\u003e\u003cspan address=\"10.1016/j.saa.2015.07.074\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZheng Y, Lin X, Wang Q, Cai W, Zhang CC. Dibenzoyl-L-cystine as organic directing agent for assembly of visible-light-sensitized luminescent AgGd (MoO\u003csub\u003e4\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e: Eu\u003csup\u003e3+\u003c/sup\u003e nanowires. Mat Res Bull. 2012;47(3):856. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.materresbull.2011.11.045\u003c/span\u003e\u003cspan address=\"10.1016/j.materresbull.2011.11.045\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKumari S, Rao AS, Sinha RK. Structural and photoluminescence properties of Sm\u003csup\u003e3+\u003c/sup\u003e ions doped strontium yttrium tungstate phosphors for reddish-orange photonic device applications. Mat Res Bull. 2023;167:112419. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.materresbull.2023.112419\u003c/span\u003e\u003cspan address=\"10.1016/j.materresbull.2023.112419\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSharma KG, Singh NR. Synthesis of CaWO\u003csub\u003e4\u003c/sub\u003e:Eu\u003csup\u003e3+\u003c/sup\u003e phosphor powders via ethylene glycol route and its optical properties. J Rare Earths. 2012;30:310. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/S1002-0721(12)60043-X\u003c/span\u003e\u003cspan address=\"10.1016/S1002-0721(12)60043-X\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSharma KG, Singh NR. Re-dispersible CaWO\u003csub\u003e4\u003c/sub\u003e:Tb\u003csup\u003e3+\u003c/sup\u003e nanoparticles: Synthesis, characterization and photoluminescence studies. J Lumin. 2013;139:98. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jlumin.2013.02.006\u003c/span\u003e\u003cspan address=\"10.1016/j.jlumin.2013.02.006\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSharma KG, Singh NR. Synthesis and luminescence properties of CaMO\u003csub\u003e4\u003c/sub\u003e:Dy\u003csup\u003e3+\u003c/sup\u003e(M\u0026thinsp;=\u0026thinsp;W, Mo) nanoparticles prepared via an ethylene glycol route. New J Chem. 2013;37:2784. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1039/C3NJ00155E\u003c/span\u003e\u003cspan address=\"10.1039/C3NJ00155E\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSharma KG, Singh TP, Singh NR. Low temperature synthesis, characterization and tunable optical properties of Eu\u003csup\u003e3+\u003c/sup\u003e, Tb\u003csup\u003e3+\u003c/sup\u003e doped CaMoO\u003csub\u003e4\u003c/sub\u003e nanoparticles. J Alloys Compd. 2014;602:275. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jallcom.2014.02.186\u003c/span\u003e\u003cspan address=\"10.1016/j.jallcom.2014.02.186\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSharma KG, Singh NS, Devi YR, Singh NR, Singh SD. Effects of annealing on luminescence of CaWO\u003csub\u003e4\u003c/sub\u003e: Eu\u003csup\u003e3+\u003c/sup\u003e nanoparticles and its thermoluminescence study. J Alloys Compd. 2013;556:94. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jallcom.2012.12.087\u003c/span\u003e\u003cspan address=\"10.1016/j.jallcom.2012.12.087\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePotanina EA, Orlova AI, Mikhailov DA, Nokhrin AV, Chuvil'deev VN, Boldin MS, Sakharov NV, Lantcev EA, Tokarev MG, Murashov AA. Spark plasma sintering of fine-grained SrWO\u003csub\u003e4\u003c/sub\u003e and NaNd(WO\u003csub\u003e4\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e tungstates ceramics with the scheelite structure for nuclear waste immobilization. J Alloys Compd. 2019;774:182. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jallcom.2018.09.348\u003c/span\u003e\u003cspan address=\"10.1016/j.jallcom.2018.09.348\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhou L, Wei J, Wu J, Gong F, Yi L, Huang J. Potential red-emitting phosphor for white LED solid-state lighting. J Alloys Compd. 2009;476:390. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jallcom.2008.09.005\u003c/span\u003e\u003cspan address=\"10.1016/j.jallcom.2008.09.005\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHe X, Guan M, Lian N, Sun J, Shang T. Synthesis and luminescence characteristics of K\u003csub\u003e2\u003c/sub\u003eBi (PO\u003csub\u003e4\u003c/sub\u003e)(MO\u003csub\u003e4\u003c/sub\u003e): Eu\u003csup\u003e3+\u003c/sup\u003e (M\u0026thinsp;=\u0026thinsp;Mo, W) red-emitting phosphor for white LEDs. J Alloys Compd. 2010;492:452. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jallcom.2009.11.138\u003c/span\u003e\u003cspan address=\"10.1016/j.jallcom.2009.11.138\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSivaganesh D, Saravanakumar S, Sivakumar V, Sasikumar S, Gopal JN, Kalpana S, Rajajeyaganthan R. Sm\u003csup\u003e3+\u003c/sup\u003e induced-SrWO\u003csub\u003e4\u003c/sub\u003e phosphor: analysis of photoluminescence and photocatalytic properties with electron density distribution studies. J Mater Sci: Mater Electron. 2020;31:8865. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s10854-020-03421-8\u003c/span\u003e\u003cspan address=\"10.1007/s10854-020-03421-8\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSeki T, Chiang KY, Yu CC, Yu X, Okuno M, Hunger J, Nagata Y, Bonn M. The bending mode of water: a powerful probe for hydrogen bond structure of aqueous systems. J Phys Chem Lett. 2020;11:8459. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1021/acs.jpclett.0c01259\u003c/span\u003e\u003cspan address=\"10.1021/acs.jpclett.0c01259\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAzev\u0026ecirc;do HV, da Silva EBS, Fernandes RS, Albuquerque AR, Gomes UU, Cavalcante DG. Green chemistry synthesis of wolframites: An investigation about stoichiometric ratios, optical, structural, vibrational, and physico-chemical properties. J Clean Prod. 2023;385:35528. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jclepro.2022.135528\u003c/span\u003e\u003cspan address=\"10.1016/j.jclepro.2022.135528\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAlexander D, Kumar BR, Mathews JM. Spectroscopic analysis of calcium tungstate and Eu doped calcium tungstate phosphor. Mater Today Proc. 2023.\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.matpr.2023.11.129\u003c/span\u003e\u003cspan address=\"10.1016/j.matpr.2023.11.129\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHasegawa M, Ohmagari H, Tanaka H, Machida K. Luminescence of lanthanide complexes: From fundamental to prospective approaches related to water-and molecular-stimuli. J Photochem Photobiol C Photochem Rev.2022;50:\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e100484.https://doi.org/10.1016/j.jphotochemrev.2022.100484\u003c/span\u003e\u003cspan address=\"100484.10.1016/j.jphotochemrev.2022.100484\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSun L, Gao R, Pan T, Ai XC, Fu L, Zhang JP. Concentration-regulated photon upconversion and quenching in NaYF\u003csub\u003e4\u003c/sub\u003e: Yb\u003csup\u003e3+\u003c/sup\u003e, Er\u003csup\u003e3+\u003c/sup\u003e nanocrystals: nonexponentiality revisited. Nanoscale. 2019;11:18150. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1039/C9NR06521K\u003c/span\u003e\u003cspan address=\"10.1039/C9NR06521K\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"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":"discover-chemistry","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [Discover Chemistry](https://link.springer.com/journal/44371)","snPcode":"44371","submissionUrl":"https://submission.nature.com/new-submission/44371/3","title":"Discover Chemistry","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Discover Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Phosphors, Nanoparticles, Photoluminescence, Charge transfer and Rare-earths","lastPublishedDoi":"10.21203/rs.3.rs-9151142/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9151142/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eA series of SrWO\u003csub\u003e4\u003c/sub\u003e doped with Eu\u003csup\u003e3+\u003c/sup\u003e and Tb\u003csup\u003e3+\u003c/sup\u003e nanoparticles were prepared by co-precipitation method using ethylene glycol as the solvent yielding highly crystalline phosphors.\u003c/p\u003e \u003cp\u003eThe phosphors were characterized by the X-ray diffraction (XRD), FT-IR spectroscopy and Transmission electron microscopy (TEM). The FT-IR spectroscopy was used to study the vibrations present in the prepared nanoparticles. The spectrum shows prominent bands at around 3300, 2853, 2890, 2924, 1383, 1650, 820 and 430\u0026ndash;440 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e; corresponding to H\u0026ndash;O\u0026ndash;H bending and O\u0026ndash;H stretching vibrations of water molecules present on the surface of nanoparticles and the O\u0026ndash;W\u0026ndash;O asymmetric stretching vibration of the WO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e tetrahedron. Characterization confirms single-phase formation, controlled morphology, and characteristic luminescence emission which can prove to be suitable for multicolour emission applications. The photoluminescence properties of the prepared nanoparticles were also studied and it is observed that by increasing the doping concentration of rare earth ions in the host i.e. SrWO\u003csub\u003e4\u003c/sub\u003e, the emission intensity of the phosphors also increased and after reaching its optimum concentration, the luminescence intensity decreased drastically. For Eu\u003csup\u003e3+\u003c/sup\u003e and Tb\u003csup\u003e3+\u003c/sup\u003e, the optimum concentrations are 10 and 7 at. %, respectively.\u003c/p\u003e","manuscriptTitle":"Photoluminescent properties of Eu 3+ , Tb 3+ doped SrWO 4 nanoparticles prepared by ethylene glycol route","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-02 09:18:45","doi":"10.21203/rs.3.rs-9151142/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-05-06T13:29:08+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-12T13:32:52+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-06T17:47:13+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-06T06:29:34+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-05T10:31:37+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"93364536620252219715067176754717090804","date":"2026-03-31T17:06:22+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"272261026843764664996182985008299091333","date":"2026-03-31T08:04:55+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"288829484203989241600014937928088266433","date":"2026-03-29T14:54:44+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"223190718216447525862276649682458187408","date":"2026-03-29T14:11:51+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-03-29T13:52:51+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-03-24T09:31:19+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-03-20T15:06:43+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-03-20T15:05:55+00:00","index":"","fulltext":""},{"type":"submitted","content":"Discover Chemistry","date":"2026-03-17T16:26:02+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"discover-chemistry","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [Discover Chemistry](https://link.springer.com/journal/44371)","snPcode":"44371","submissionUrl":"https://submission.nature.com/new-submission/44371/3","title":"Discover Chemistry","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Discover Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"15050a96-522f-491c-b9df-ed9dfec3508e","owner":[],"postedDate":"April 2nd, 2026","published":true,"recentEditorialEvents":[{"type":"decision","content":"Revision requested","date":"2026-05-06T13:29:08+00:00","index":"","fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"in-revision","subjectAreas":[],"tags":[],"updatedAt":"2026-05-06T13:41:39+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-02 09:18:45","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9151142","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9151142","identity":"rs-9151142","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}