Self-generated semiconductor/relaxor antiferroelectric composite ceramics with high energy storage properties

Self-generated semiconductor/relaxor antiferroelectric composite ceramics with high energy storage properties | 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 Self-generated semiconductor/relaxor antiferroelectric composite ceramics with high energy storage properties Yangyang Zhang, Haixia Li, Liqin Yue, Pengyuan Fan This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8894516/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 12 You are reading this latest preprint version Abstract In this reserch, (1- x )NaNbO 3 - x BiFeO 3 solid solutions were reported to clearly show relaxor antiferroelectric phase structure dependent energy storage properties, evolving from W rec = 1.63 J/cm 3 and η = 27% in the case of x = 0.04 at 300 kV/cm to 7.4 J/cm and 83.4% in the case of x = 0.12 at 500 kV/cm. To further decrease the dielectric loss and improve the breakdown strength of 0.88NaNbO 3 -0.12BiFeO 3 ceramic, MnO 2 was incorporated into it. In particular, When 1wt.% MnO 2 was added, a MnFe 2 O 4 /0.88NN-0.12BF-Mn semiconductor/relaxor composite ceramic was unexpectedly obtained. A small amount of semiconductor second phase significantly increases the breakdown field strength of the material, thereby obtaining a super large energy storage density W rec of 13.4 J/cm 3 and excellent energy efficiency η of 87.4% at 700 kV/cm. The finding of this study provide valuable insights of self-generated semiconductor/relaxor composite structure to obtain good energy storage performence in NaNbO 3 -based lead-free ceramics. Relaxor antiferroelectric Composite Energy storage NaNbO3 Lead-free Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 1. Introduction As a kind of electric energy storage mode, ceramic based dielectric energy storage capacitor is the core part of many pulse power electronic systems, including pulse power weapons, power distribution devices, electric vehicles and other fields [ 1 – 5 ] . At present, the requirements of miniaturization, integration and low power consumption for dielectric energy storage capacitors are put forward in the related military and civil fields, and the evolution of dielectric materials with higher energy storage characteristics becomes the key to meet the current needs [ 6 – 8 ] . Usually, the energy storage parameters of ceramic capacitors can be easily obtained by calculating the integral of the polarization electric field ( P - E ) hysteresis loop, as shown below: where E is the the electric field, P max is the saturated polarization, and P r is the remanent polarization. Based on the above formula, we can design a new type of ceramic capacitor with high energy storage performance, which should simultaneously meet the requirements of high breakdownstrength, large P max and low P r . It is evident that under the applied electric fields, when P max is large but P r is at its minimum, W rec can be greatly enhanced. Antiferroelectric ceramics are one of the most important ceramic capacitors developed to date due to their higher energy storage density than ferroelectric and linear ceramics, as well as their high P max , low P r , and moderate breakdown strength E b [ 5 , 8 ] . The energy storage performance of various types of AFE ceramics have been studied, including lead based and lead-free solid solutions. The W rec values of (Pb,La)(Zr,Sn,Ti)O 3 , and AgNbO 3 AFE ceramics are 5.56 J/cm 3 and 4.4 J/cm 3 , respectively [ 9 – 16 ] . However, due to the large hysteresis between AFE-FE and FE-AFE phase transitions, normal AFE ceramics with macroscopic domains typically display typical double P - E hysteresis loops, resulting in relatively low energy storage efficiency [ 10 , 15 , 16 ] . Meanwhile, considering the harmful effects of lead oxide on the human health and environment, lead-free AFE ceramics have received more attention in recent years [ 17 – 29 ] . NaNbO 3 (NN)-based ceramics have become attractive lead-free antiferroelectric ceramics due to their complex phase transitions and enormous potential as a substitute for lead based materials [ 30 , 31 ] . Pure NaNbO 3 ceramics belong to the AFE orthogonal P phase (Pbma space group) at 25℃, and exhibit AFE orthogonal R phase (Pnma space group) when heated at approximately 360 ° C. Nevertheless, due to the irreversible phase transition from AFE to FE induced by an external electric field, pure NaNbO 3 ceramics should exhibit poor energy storage performance [ 32 – 35 ] . Recent researches have shown that by adding ABO 3 perovskite compound, repeatable double P - E curves can be achieved in NaNbO 3 -based ceramics. This should enhance the potential application of this ceramic material in energy storage capacitors [ 36 – 40 ] . For example, it has been reported that CaZrO 3 can stabilize the AFE P phase, increase the W rec and η of NaNbO 3 ceramics to about 0.55 J/cm 3 and 63%, while Na 0.5 Bi 0.5 TiO 3 has been reported to promote the formation of AFE R phase at room temperature, achieving good energy storage performance ( W rec of 12 J/cm 3 , and η of 70%) [35,36.38] . In brief, NaNbO 3 based ceramics with AFE R phase (also known as NaNbO 3 based relaxor antiferroelectric ceramics) have relatively low hysteresis P - E loops, indicating higher energy storage performance [ 37 – 40 ] . Moreover, the effect of a small amount of transition-metal oxides addition on the energy storage performance of 0.92NaNbO 3 -0.08Bi(Mg 0.5 Ti 0.5 )O 3 (0.92NN-0.08BMT) relaxor antiferroelectric ceramics was also studied. For example, doping 0.5 mol% MnO 2 , CuO and CeO 2 can significantly improve the behaviour, defect structure and bulk resistivity of 0.92NN-0.08BMT ceramics, thus greatly improving the breakdown strength. As a result, both high W rec of 5.57 J/cm 3 and η of 71% under 480 kV/cm were achieved in NN-BMT-Mn ceramic [ 41 ] . BiFeO 3 (BF) has a strong polarization ability and a perovskite structure similar to Na 0.5 Bi 0.5 TiO 3 (NBT) [ 18 – 20 ] . It is expected that BF can combined with NN to form a solid solution structure and enhance the energy storage performance of NN. In this research, the energy storage performance of NN ceramics has been improved by introducing BF to NN. As expected, 0.88NaNbO 3 -0.12BiFeO 3 (0.88NN-0.12BF) ceramic represents comprehensive advantages of high W rec of 7.4 J/cm 3 , high η of 83.4%, excellent frequency stability of 1-100 Hz and wide temperature range of 25ཞ125 ℃. Besides, as a typical multivalent element, Mn forms various valence ions during sintering process to generate multiple impacts on ceramics, including pinning ferroelectric domain, enhancing densification, etc [ 21 ] . Hence, Mn has been considered as one of the most effective elements for improving energy storage performance, and it’s effectiveness has been confirmed by many studies [ 21 , 41 ] . In this paper, the MnO 2 doped 0.88NN-0.12BF ceramics were prepared. The influences of Mn doping on energy storage properties have been discussed. Specially, when 1 wt.% was added to the 0.88NN-0.12BF ceramic, we found that MnO 2 was not completely absorbed by the main lattice. Some Mn ions enter into the lattice to replace Fe ions, while the precipitated Fe ions react with MnO 2 to form a second phase of semiconductor MnFe 2 O 4 . As a result, the defect structure, bulk resistivity and dielctric loss were improved, thus greatly improving dielectric breakdown strength, and further reduced residual polarization and hysteresis. The orthorhombic antiferroelectric R phase and semiconductor phase synergistically benefit to the extremely large W rec of 14.3 J/cm 3 and very high η = 88.7% at 700 kV/cm. 2. Experiment Ceramic powders of (1- x )NaNbO 3 - x BiFeO 3 ( x = 0.04–0.16) were synthetized by the solid-state reaction process. Powders of Na 2 CO 3 (99.8%, Sigma-Aldrich), Nb 2 O 5 (99.8%, Alfa-Aesar), Bi 2 O 3 (99.5%, Sigma-Aldrich) and Fe 2 O 3 (99.5%, Sigma-Ald rich) were used as raw materials. The chemical stoichiometry amounts of the powder will be measured based on each composition formula. Subsequently, the mixture was ball milled with ethanol and zirconia balls in nylon pots for 12 hours. Then dry the slurry in the air. The mixed powder is poured into a crucible, and calcined at 750°C for 2 hours, followed by calcination at 850°C for 2 hours. The calcined powder was ball milled again for 8 hours to obtain uniform particle siz, dried and uniaxially pressed into pellets. The NaNbO 3 ceramics were sintered at 1350°C for 3 hours, while all NN-BF pellets were sintered at 1180°C for 3 hours to achieve densification. It is worth noting that these samples need to be embedded in the calcined powder to prevent the evaporation of sodium and bismuth elements during the sintering process. The density of sintered ceramic samples was tested according to Archimedes principle. The microstructure was characterized by field-emission scanning electron microscope (FE-SEM, Hitachi S4800, Tokyo, Japan). The samples were polished and thermally etched at 1000–1050 ℃ for 0.5 h before testing. The valence states of Na, Nb, Bi, Fe, O and Mn in MnO 2 doped 0.88NN-0.12BF sample powders were determined by means of X-ray photoelectron spectroscopy (XPS, PHI 5000Versa probe, Japan) equipped with an Al-Kα with energy of = 1486.6 eV, in which binding energies were corrected to the C 1s signal at 284.6 eV from adventitious carbon. Before XPS testing, the sample should be dried under vacuum for 12 hours to prevent the influence of adsorbed H 2 O. The crystallographic structures of sintered samples were measured by powder X-ray diffraction (XRD, PANalyticals, Cambridge, UK). Data from the XRD were analyzed by the rietveld method using the GSAS. Silver paste (Youleguang photoelectric technology co., LTD., SA-6131, Wuhan, China) was evenly covered on the top and bottom of discs, and then fired at 550°C for 30 min to obtain dense and smooth electrodes for electric testing. Frequency and temperature dependences of dielectric constant (ε r ) and loss(tan δ) were tested at the temperature range of -160 to 200 ◦C at 0.1, 1, 5, 10, 100 and 500 kHz using an LCR meter (Julang technology co., Ltd,, TZDM-RT-600, Haerbin, China). The impedance spectroscopy were performed by using an LCR meter (Tonghui Electronic Co., Ltd,, TH2382, Changzhou, China) during heating. The electric field-induced polarization ( P - E ) were characterized by using the ferroelectric measuring system (aix ACCT Co., Aachen, Germany). 3. Results and discussion Figure 1 (a) and (c) illustrates the bipolar and unipolar P - E loops of (1- x )NN- x BF ceramics measured at 300 kV/cm and 10 Hz, respectively. Accompanying the composition induced phase transition, an obvious change in the P - E curves can be found. The x = 0.04, 0.06 and 0.08 samples display reversible square-like double P - E loops with large polarization hysteresis, corresponding to high P r values, leading a poor energy-storage properties in these orthorhombic P phase (Pbma) phase compositions, as indicted in Fig. 1 (d). As x increases from 0.08 to 0.16, double square P - E curves gradually transform into slim curves with near-zero P r . These slim curves were formed due to the significantly enhanced dielectric relaxation characteristics of the AFE orthorhombic R phase (Pnma), resulting in a signicantly increased phase transition and a rapid polarization response [ 42 – 51 ] . Figure 1 (b) shows the variations in P max , P r , and ΔP ( P max - P r ) for NN-BF ceramics. The ΔP first increases and then decreases when x is in the range of 0.06–0.16, indicating that BF doping enhences the relaxor characteristics of the NN-BF, resulting in an increase in ΔP . The large ΔP value is favorable to improve the energy storage performance. As a result, obviously improved energy storage performance of large W rec = 2.93 J/cm 3 and 3.32 J/cm 3 and desirable η = 81.5% and 88.5% were obtained in x = 0.10 and 0.12 ceramics at 300 kV/cm, respectively, as shown in Fig. 3 (d), exhibiting obvious advantages of the AFE R phase over the AFE P phase. Figure 2 (a) and (b) show the temperature dependence of relative dielectric constant and loss tangent of (1- x )NaNbO 3 - x BiFeO 3 ceramics at 1, 10, 100 and 500 kHz. The 0.90NN-0.10BF and 0.88NN-0.12BF samples both show obvious dielectric relaxation characteristics. They belong to AFE orthorhombic R phase. When BF is dissolved in NN, the existence of Bi 3+ , Fe 3+ , and A-site vacancies whose charges and radii are different from the host ions Na + and Nb 5+ are in charge of breaking the long-range FE ordering and resulted in the relaxor characteristics. It can be observed that the degree of dielectric relaxation raises from 0.90NN-0.10BF to 0.88NN-0.12BF, mainly manifested by the reduce of the temperature at the maximum dielectric permittivity ( T m ) and the increase of the relaxation factor ΔT relax (= T m , 0.5 MHz - T m , 1 kHz ). The occurrence of dielectric relaxor phenomenon is often referred to the improved random fields caused by the local composition disorder [ 42 – 45 ] . Figure 2 (c) and (d) show the XRD patterns of the 0.90NN-0.10BF and 0.88NN-0.12BF ceramics, respectively. The results showed a typical perovskite structure, and no obvious second phases appear. All the peaks display an orthorhombic phase structure at room temperature. Rietveld refinement is completed by a single-phase refinement approach ( pnma ) in the GSAS2. The R wp is 2.7% and 2.8, respectively. The data showed that the Bi 3+ has taken the place of the A-site Na + in the matrix of two crystallographic sites; meanwhile, the B-site Nb 5+ (0.64 Å) was replaced by Fe 3+ (0.605 Å). Compared with pure NaNbO 3 ceramics, the calculated unit cell parameters (a = 5.54 Å, b = 8.38 Å, c = 5.53 Å) and (a = 5.54 Å, b = 7.82 Å, c = 5.52 Å) show little change. Due to the low goodness value of χ 2 and R wp , it proves the reliability of the fitting with the cubic model. Table 1 Structural parameters of rietveld refinement of orthorhombic phase ( pnma ) for 0.90NN-0.10BF and 0.88NN-0.12BF. Samples Structures and parameters of unit cell (Å) Fitting parameters 0.90NN-0.10BF a = 5.54 (Å); b = 8.38(Å); c = 5.53 (Å) α = β = γ = 90° Volume = 242.4 (Å 3 ) ρ = 4.98 g/cm 3 χ 2 = 2.134 R wp = 0.027 0.88NN-0.12BF a = 5.54 (Å); b = 7.82 (Å);c = 5.52(Å); α = β = γ = 90° Volume = 239.3 (Å 3 ) ρ = 5.007 g/cm 3 χ 2 = 2.123 R wp = 0.028 Figure 3 displays the SEM images of (1- x )NaNbO 3 - x BiFeO 3 ceramics. The samples of 0.90NN-0.10BF and 0.88NN-0.12BF exhibit homogenous and dense microstructure with an average grain size of 4.1 µm and 4.4 µm, respectively. The relative density of 0.90NN-0.10BF and 0.88NN-0.12BF is about 97%. Figure 4 (a) and (b) gives the unipolar P - E loops of (1- x )NaNbO 3 - x BiFeO 3 ceramics under different electric fields at room temperature and 10 Hz. The 0.90NN-0.10BF samples exhibit high polarization hysteresis, corresponding to high P r values. Therefore, as shown in Fig. 4 (c), the energy storage performance in these AFE R phase compositions is poor. An significantly slim P - E loop can be achieved in 0.88NN-0.12BF ceramic. These slender curves were generated due to significantly increased dielectric relaxation features of the AFE R phase, leading to a rapid polarization response and obviously enhanced phase transition [ 46 – 49 ]. This is very consistent with the analysis result in Fig. 2 (b). Therefore, adding BF can availably raise the stability of the AFE phase in NN. As a result, as shown in Fig. 4 (d), obviously improved energy storage properties of W rec = 7.6 J cm − 3 and η = 83.4% were achieved in 0.88NN-0.12BF ceramics under 500 kV/cm, showing outstanding advantages of the AFE R phase over the AFE P phase. The temperature stability of unipolar P - E loops and energy storage performance for 0.88NN-0.12BF ceramic from 25°C to 125°C at E = 300 kV/cm at 10Hz are displayed in Fig. 5 (a) and (b). The P-E loop shows an excellent temperature stability when the temperature rises, are shown in Fig. 5 (a), which may be beneficial for the stability of the AFE R phase coexisting in 0.88NN-0.12BF ceramics over a wide temperature range. Thus, W rec only reduced from 3.39 J/cm 3 to 3.26 J/cm 3 , which is a decrease of about 3.8% between 25℃ and 125 ℃. The excellent temperature stability of W rec indicates that 0.88NN-0.12BF ceramic is a promising lead-free AFE relaxor suitable for high-temperature dielectric capacitors. Besides, the frequency stability of unipolar P - E and W rec is studied, as shown in Fig. 5 (c) and (d). This results display that W rec increases slightly with the frequency increases. The W rec in creased from 3.25 J/cm 3 to 3.46 J/cm 3 , which indicates it reduced by only 6.5% between 0.1 Hz and 500 Hz, indicating that 0.88NN-0.12BF ceramics have excellent frequency stability. The dispersion characteristics of relaxor AFE are associated with the orientation and fragmentation mechanism of nanodomains in low-voltage cycles, indicating that these processes are time-dependent due to the assumed dynamics [ 50 – 55 ] . In order to further optimize the energy storage performance, the composition with x = 0.12 was doped with 0.5, 1 and 2 wt.% MnO 2 . The SEM images at backscattered electrons (BSE) mode of polished and thermally etched MnO 2 doped NN-BF ceramics are presented in Fig. 6 (a)-(d). All specimens were well densified with only a few pores. When 0.5wt.% MnO 2 is added, the grain size slightly decreases and the uniformity is improved. Increasing the MnO 2 content to 1 wt.%, the presence of a second phase was discovered. Continuing to add up to 2 wt.%, it was found that the second phase still existed and had a larger quantity. Figure 6 (e) exhibits the unipolar P - E loops of MnO 2 doped 0.88NN-0.12BF ceramics measured at maximum breakdown electric field and 10 Hz. The E b varied evidently when MnO 2 was added, so all measurements were measured at the optimal electric field rather than an identical one. All P - E loops displayed similar features, manifesting as a relatively slim shape and small P r . As seen from Fig. 6 (f), adding 0.5 wt.% MnO 2 to NN-12BF, the breakdown electric field has a slight improvement, and no second phase was found (see Fig. 6 (b)). The E b , W rec η and value significantly increased when 1.0 wt% MnO 2 was applied, the second phase was observed (see Fig. 6 (c)). This indicates that the generation of the second phase has a significant impact on the energy storage performance of the material system. However, adding 2 wt% MnO 2 can lead to a sharp decrease in breakdown field strength, which may be related to the content of the second phase (see Fig. 6 (d)). Overall, a appropriate amount of MnO 2 addition can form a composite ceramic structure, which can effectively improve the breakdown field strength, thus enhancing energy storage performance. In order to further understand the chemical composition of the second phase. Energy Dispersive Spectrometer (EDS) measurement was carried out. The SEM pictures of the fracture surface of thermal etching at backscattered electron (BSE) mode and the distribution of two-dimensional elements in the 0.88NN-0.12BF + 1 wt.% MnO 2 ceramic are presented in Fig. 7 (a). It can be observed that some dark and small grains arelocated in the gaps between larger grains. By using two-dimensional distribution and corresponding mapping of element were used to characterize it, the composite microstructure of 0.88NN-0.12BF + 1 wt.% MnO 2 ceramic can be intuitively displayed. It can be observed that the chemical composition of this ceramic sample is uneven, because Na, Nb and Bi occupy the same area and are interconnected. A small amount of Fe, Mn and O occupies the same area as Na, Bi and Nb, and a large amounts of Fe, Mn and O occupies the isolated and remaining areas. This proves that the main grains are ascribed to 0.88NaNbO 3 -0.12Bi(Fe 1− y Mn y )O 3 (abbreviated as 0.88NN-0.12BF-Mn), while the second phase grains are consist of Fe, Mn and O elements. That is to say, after adding 1% MnO 2 , Mn 4+ ions enter the main crystal phase of NN-12BF and replace Fe 3+ ions. The precipitated Fe 3+ ions react with the remaining MnO 2 to form the second phase. This second phase grains are mainly embedded in the boundaries of the 0.88NN-0.12BF-Mn, achieving a 0–3 type composite ceramic.Then we analyzed the their EDS point analysis spectrum, and the molar ratios of elements were obtained (see Fig. 7 (b)). The composition values of the second phase were determined by EDS can be written approximately as Mn 0.141 Fe 0.247 O 0.612 . To further confirm the crystal structure of the second phase more accurately. The XRD pattern of the sintered 0.88NN-0.12BF + 1 wt.% MnO 2 ceramic powders was tested. The result indicates the NN-12BF-Mn major crystal phase is perovskite structure, and it exhibits an orthorhombic phase at RT. More importantly, MnFe 2 O 4 semiconductor phase was detected (see Fig. 8 ). The rietveld renement results are summarized in Table 2 . The composite ceramic sample consists of 98.6 wt.% 0.88NN-0.12BF-Mn and 1.4 wt.% MnFe 2 O 4 . The unit cell parameters of 0.88NN-0.12BF-Mn are : a = 5.54 Å, b = 7.82 Å, c = 5.53 Å. Table 2 Structural parameters of rietveld refinement of orthorhombic phase ( pnma ) for 0.88NN-0.12BF + 1 wt.% MnO 2 ceramics Composition of samples Phase fraction (wt.%) Structures and parameters of unit cell (Å) 0.88NN-0.12BF-Mn 98.6% a = 5.54 (Å); b = 7.82 (Å); c = 5.53 (Å) α = β = γ =90° Volume = 239.4 (Å 3 ) ρ = 4.98 g/cm 3 MnFe 2 O 4 1.4% Figure 9 (a) presents P - E loops of MnFe 2 O 4 /0.88NN-0.12BF-Mn semiconductor/relaxor antiferroelectric composite ceramic measured in different applied electric field under the room temperature. Obviously, the P max increases monotonously with the increase of electric field up to 700 kV /cm, and a low-hysteresis P - E curves with P r ~ 0 µC/cm 2 can be measured within the studied electric field range, resulting in an ultra-high W rec of 13.4 J/cm 3 and a desirable η of 87.4%. Compared with pure 0.88NN-0.12BF ceramic, the breakdown strength E b and W rec of MnFe 2 O 4 /0.88NN-0.12BF-Mn composite ceramic are significantly improved by 40% and 78%, respectively. Figure 10 (a) shows the variation of permittivity ε r and dielectric loss tanδ of MnFe 2 O 4 /0.88NN-0.12BF-Mn semiconductor/relaxor composite ceramics with temperature at different frequencies. Compared with pure 0.88NN-0.12BF ceramic, the dielectric relaxation degree MnFe 2 O 4 /0.88NN-0.12BF-Mn semiconductor/relaxor composite ceramic are further improved, and the dielectric constant greatly decreases in the whole temperature range. Impedance spectroscopy is an excellent tool for studying dielectric relaxation and electrical conduction mechanisms. The Z′- Z′′ curves of different samples achieved at 500°C in the frequency range of 20 Hz to 1 MHz, as shown in Fig. 10 (b), where Z′ and Z′′ mean the real and imaginary parts of impedance, respectively. The results show that all of the 0.88NN-0.12BF and 0.88NN-0.12BF + 1 wt% MnO 2 ceramics present a nearly single impedance arc. These arcs were found to be unable to be fitted by an RC equivalent circuit. This result shows that both grains and grain boundaries contribute significantly to impedance. As shown in the illustration of Fig. 10 (b), in order to divide the respective contributions of grain boundaries and grains, an equivalent simulation circuit can be constructed for fitting. This circuit consists of a series of grain boundaries and grains components, including grain boundary capacitance (C gb ), grain boundary resistance (R gb ), grain capacitance (C g ) and grain resistance (R g ). The good consistency between the fitting lines and the test results suggests that the method of adopted fitting circuit is reliable. The result show that Z′values of 0.88NN-0.12BF + 1 wt% MnO 2 sample is much bigger than 0.88NN-0.12BF at 500°C. A larger Z 'value is usually associated with higher voltage resistance, suggesting that the insulation performance is improved after doping MnO 2 . This may be related to the large resistivity of the 0.88NN-0.12BF-Mn grains and second phase MnFe 2 O 4 induced local electric field. The E b value of MnO 2 modified 0.88NN-0.12BF ceramics is significantly associated with the uneven distribution of local electric field (LEF) causing by the formation of the second phase [ 42 , 47 – 49 ] . The distribution of LEF depends on the second phase content and microstructure in ceramics. To explore the influence of MnFe 2 O 4 semiconductor second phase on the E b of MnFe 2 O 4 /0.88NN-0.12BF-Mn composite ceramics, according to the principle of finite element analysis, the electric field distribution inside MnFe 2 O 4 /0.88NN-0.12BF-Mn composite ceramics was simulated using ANSYS Maxwell software under the 200 kV/cm, as shown in Fig. 11 . Circular particles represent MnFe 2 O 4 ( ε r = 5) second phase, rectangular matrix represents 0.88NN-0.12BF-Mn phase ( ε r ≈ 600). The results indicate that due to the significant difference in ε r , more applied voltage will be concentrated in MnFe 2 O 4 . On the MnFe 2 O 4 phase with lower ε r , the LEF in the 0.88NN-0.12BF-Mn matrix is weakened (Fig. 11 (a)). Therefore, the second phase of MnFe 2 O 4 semiconductor generated by adding MnO 2 can increase the E b value of MnFe 2 O 4 /0.88NN-0.12BF-Mn composite ceramics. Therefore, the redistribution of LEF induced by the second phase of MnFe 2 O 4 can well explain the effect of MnFe 2 O 4 on the breakdown of MnFe 2 O 4 /0.88NN-0.12BF-Mn composite ceramics. These findings are consistent with the previous research of Zhang et al ., who successfully increased E b from 132 kV/cm in pure Ba 0.4 Sr 0.6 TiO 3 ceramics to 331 kV/cm in Ba 0.4 Sr 0.6 TiO 3 /MgO by compounding low dielectric constant second phase MgO into Ba 0.4 Sr 0.6 TiO 3 ceramic matrix, almost 2.5 times higher [ 56 ] . Li et al . used finite element software (COMSOL) to numerically simulate the distribution of electric potential and LEF, and studied the influence of the second phase on the E b value of composite materials [ 57 ] . Based on simulations and experiments, it was found that the aggregation phenomenon caused by the excessive distribution of low dielectric constant second phases ultimately leads to more electric fields concentrated on this part of the material. The electric fields distributed on this part of the material will be much higer than the range that the material can tolerate, resulting in a decrease in the E b of the composite material. Consistent findings have also been found in the 0–3 type composite ceramics of Bi 0.5 Na 0.5 TiO 3 -SrTiO 3 -AgNbO 3 :SiO 2 and Bi 0.5 Na 0.5 TiO 3 -BaTiO 3 -K 0.5 Na 0.5 NbO 3 :ZnO [ 23 , 26 ]. In addition, as shown in Fig. 11 (b), some studies have shown that the second phase of semiconductors can fix free electrons through strong electrostatic attraction, forming a local electric field and hindering the injection and transmission of charges in dielectric composite ceramics, resulting in a significant improvement in breakdown performance [ 58 ] . 4. Conclusions The (1- x )NN- x BF lead-free solid solution ceramics were found to exhibit an obvious phase transformation from an AFE P phase to an AFE R phase with increasing BF content. The optimum energy-storage density of 7.4 J/cm 3 were achieved in the x = 0.12 sample with an AFE R phase structure under 500 kV/cm. In addition, it also has good frequency and temperature stability. To further improve the properties of NN−12BF, a small amount of MnO 2 was added. The obviously improved E b values were achieved by doping 1 wt.% MnO 2 . SEM and XRD prove that 0.88NN−0.12BF + 1 wt.% MnO 2 ceramic consists of two phases, namely 0.88NN−0.12BF-Mn relaxor AFE and a few semiconductor MnFe 2 O 4 . It has been founded that a part of Mn element enters the NN-12BF main lattice and a small amount of semiconductor second phase is generated simultaneously. On the one hand, MnO 2 as an effective sintering aid for densification and an acceptor dopant for relaxation can improve the breakdown field strength and energy-storage efficiency of NN-12BF. On the other hand, a small amount of semiconductor second phase forms a local electric field, which can resist the transmission of charges, resulting in a greatly improvement in breakdown performance. This synergistic effect significant increases the energy-storage properties of the ceramic matrix, achieving a super high energy storage density of 13.4 J/cm 3 and a high energy storage efficiency of 87.4% under 700 kV/cm. Declarations Acknowledgments This research was supported by the Project of Henan Province Science and Technology (232102221003, 232102210183), the Special Project of Zhengzhou Basic Research and Application Basic Research (ZZSZX202435, ZZSZX202106), and the Postgraduate Education Reform and Quality Improvement Project of Henan Province (YJS2023JD67). References C. Liu, F. Li, L.P. Ma, H.M. Cheng, Advanced materials for energy storage. Adv. Mater. 22 , E28–E62 (2010) H. Pan, S. Lan, S. Xu, Q. Zhang, H. Yao, Y. Liu, F. Meng, E.J. Guo, L. Gu, D. Yi, X.R. Wang, H. Huang, J.L. MacManus-Driscoll, L.Q. Chen, K.J. Jin, C.W. Nan, Y.H. Lin, Ultrahigh energy storage in superparaelectric relaxor ferroelectrics. Science. 374 , 100–104 (2021) X. 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Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 13 Mar, 2026 Reviews received at journal 12 Mar, 2026 Reviews received at journal 09 Mar, 2026 Reviews received at journal 04 Mar, 2026 Reviewers agreed at journal 02 Mar, 2026 Reviewers agreed at journal 01 Mar, 2026 Reviewers agreed at journal 28 Feb, 2026 Reviewers agreed at journal 24 Feb, 2026 Reviewers invited by journal 19 Feb, 2026 Editor assigned by journal 17 Feb, 2026 Submission checks completed at journal 17 Feb, 2026 First submitted to journal 16 Feb, 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. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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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-8894516","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":593796533,"identity":"d67f8c0c-3065-4c24-9a76-3f68fbf0c84b","order_by":0,"name":"Yangyang Zhang","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA30lEQVRIiWNgGAWjYHACNhAhZyAB4TE2EKvFGKgFrJp4LYkbiNZicCP92YOfO2rTt0u3P3/Mw2Aju+EA87MH+LUkpBv2njmeu3POGcNmHoY04w0H2MwNCGg5JsHbdix3w40cRqCWw4kbDvCwSeDXktgm+bftWDrQhQ+BWv4ToyWZTZq3rSYBaB3IYQcIa5E884xNWrbtgCHQYYYz5xgkG888zGaGVwvf8fRnkm/b6uSBDnvw4U2FnWzf8eZneLUoXEgAUYdh7gRiZnzqgUC+/wCIqiOgbBSMglEwCkY0AAB2KVBvqH71WwAAAABJRU5ErkJggg==","orcid":"","institution":"Huanghe Science and Technology College","correspondingAuthor":true,"prefix":"","firstName":"Yangyang","middleName":"","lastName":"Zhang","suffix":""},{"id":593796534,"identity":"84cf4a98-05d2-43db-a02b-f588db379d67","order_by":1,"name":"Haixia Li","email":"","orcid":"","institution":"Huanghe Science and Technology College","correspondingAuthor":false,"prefix":"","firstName":"Haixia","middleName":"","lastName":"Li","suffix":""},{"id":593796535,"identity":"68df7002-7436-4987-a2fd-a1f6a5e003ee","order_by":2,"name":"Liqin Yue","email":"","orcid":"","institution":"Huanghe Science and Technology College","correspondingAuthor":false,"prefix":"","firstName":"Liqin","middleName":"","lastName":"Yue","suffix":""},{"id":593796536,"identity":"c5d2ad45-21ab-478e-af0b-804a465052a7","order_by":3,"name":"Pengyuan Fan","email":"","orcid":"","institution":"Huazhong University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Pengyuan","middleName":"","lastName":"Fan","suffix":""}],"badges":[],"createdAt":"2026-02-16 15:53:14","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8894516/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8894516/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":103217880,"identity":"e1bb4c03-fe5f-4f5f-8f8b-974a58dd8d97","added_by":"auto","created_at":"2026-02-23 09:51:05","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":195310,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Bipolar \u003cem\u003eP\u003c/em\u003e-\u003cem\u003eE\u003c/em\u003e loops, (b) \u003cem\u003eP\u003c/em\u003e\u003csub\u003emax\u003c/sub\u003e, \u003cem\u003eP\u003c/em\u003e\u003csub\u003er \u003c/sub\u003eand \u003cem\u003eΔP\u003c/em\u003e\u003csub\u003e \u003c/sub\u003e, (c) unipolar \u003cem\u003eP\u003c/em\u003e-\u003cem\u003eE\u003c/em\u003e loops, (d) \u003cem\u003eW\u003c/em\u003e\u003csub\u003erec\u003c/sub\u003e and \u003cem\u003eη\u003c/em\u003e of (1-\u003cem\u003ex\u003c/em\u003e)NN-\u003cem\u003ex\u003c/em\u003eBF\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-8894516/v1/967f589fdcac13734d40ad5b.png"},{"id":103217881,"identity":"ad6865df-e1fe-4b3f-adfb-e14d58b18c14","added_by":"auto","created_at":"2026-02-23 09:51:05","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":185059,"visible":true,"origin":"","legend":"\u003cp\u003eThe temperature dependence of dielectric permittivity and loss for \u0026nbsp;0.90NN-0.10BF and 0.88NN-0.12BF ceramics. Rietveld refinement results of XRD patterns for 0.90NN-0.10BF and 0.88NN-0.12BF ceramics.\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-8894516/v1/8b30c377573fc76dfd2c61a3.png"},{"id":103505643,"identity":"35317927-151d-489b-96b9-6f0442428c4d","added_by":"auto","created_at":"2026-02-26 13:32:21","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":88375,"visible":true,"origin":"","legend":"\u003cp\u003eSEM images on the surfaces of 0.90NN-0.10BF and 0.88NN-0.12BF ceramics\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-8894516/v1/733144bec10b890af60874ad.png"},{"id":103217883,"identity":"bcf22197-9fe7-485d-bf59-f884e51ac089","added_by":"auto","created_at":"2026-02-23 09:51:05","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":163524,"visible":true,"origin":"","legend":"\u003cp\u003eUnipolar \u003cem\u003eP\u003c/em\u003e-\u003cem\u003eE\u003c/em\u003e loops for (a) 0.90NN-0.10BF and (b) 0.88NN-0.12BF under different electric fields at 10 Hz; \u003cem\u003eW\u003c/em\u003e\u003csub\u003etotal\u003c/sub\u003e, \u003cem\u003eW\u003c/em\u003e\u003csub\u003erec\u003c/sub\u003e and \u003cem\u003eη\u003c/em\u003e of (c) 0.90NN-0.10BF and (d) 0.88NN-0.12BF\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-8894516/v1/0dc3032ef9d5c6bf1fa8197a.png"},{"id":103217885,"identity":"0449c611-b4d8-491f-b9d0-3901a64c80ec","added_by":"auto","created_at":"2026-02-23 09:51:05","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":170966,"visible":true,"origin":"","legend":"\u003cp\u003e(b) Temperature- and frequency- dependent \u003cem\u003eP\u003c/em\u003e-\u003cem\u003eE\u003c/em\u003e loops for 0.88NN-0.12BF ceramics\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-8894516/v1/a3fcffbf38b41d8d584843d6.png"},{"id":103217890,"identity":"9ccbc260-f4a3-4f2e-bd63-91b62df4b5b3","added_by":"auto","created_at":"2026-02-23 09:51:05","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":217434,"visible":true,"origin":"","legend":"\u003cp\u003eSEM images of (1-\u003cem\u003ex\u003c/em\u003e)NN-\u003cem\u003ex\u003c/em\u003eBF ceramics doped with (a)0 wt.%, (b)0.5 wt.%, (c)1 wt.% and (d)2 wt.% MnO\u003csub\u003e2\u003c/sub\u003e. The energy storage performance of MnO\u003csub\u003e2 \u003c/sub\u003edoped NN-BF ceramics for (e) unipolar \u003cem\u003eP\u003c/em\u003e-\u003cem\u003eE\u003c/em\u003e loops, (f) the \u003cem\u003eW\u003c/em\u003e\u003csub\u003erec\u003c/sub\u003e, \u003cem\u003eη\u003c/em\u003e and \u003cem\u003eE\u003c/em\u003e\u003csub\u003eb\u003c/sub\u003e.\u003c/p\u003e","description":"","filename":"floatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-8894516/v1/e785e1cb37370b674455c61f.png"},{"id":103505882,"identity":"bd05994f-aab2-453d-a533-9d2e6f7acb08","added_by":"auto","created_at":"2026-02-26 13:33:21","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":565398,"visible":true,"origin":"","legend":"\u003cp\u003e(a)The backscattered electron and element mappings of micrographs of the 0.88NN-0.12BF+ 1 wt.% MnO\u003csub\u003e2\u003c/sub\u003e ceramics. (b) EDS point analysis spectrum of main grain and second phase grain of the 0.88NN-0.12BF + 1 wt.% MnO\u003csub\u003e2\u003c/sub\u003e ceramic.\u003c/p\u003e","description":"","filename":"floatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-8894516/v1/c9f4ae91622b677f2ed6e8a9.png"},{"id":103217886,"identity":"6ea36c68-5d88-47f8-bd29-907a5c119c68","added_by":"auto","created_at":"2026-02-23 09:51:05","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":82560,"visible":true,"origin":"","legend":"\u003cp\u003eRietveld refinement results of XRD patterns for 0.88NN-0.12BF + 1 wt.% MnO\u003csub\u003e2\u003c/sub\u003e ceramics\u003c/p\u003e","description":"","filename":"floatimage8.png","url":"https://assets-eu.researchsquare.com/files/rs-8894516/v1/866b70e8a56cf0a5f7a7237a.png"},{"id":103505935,"identity":"907749b6-9df0-4d43-9297-3d1fec1126a8","added_by":"auto","created_at":"2026-02-26 13:33:34","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":123845,"visible":true,"origin":"","legend":"\u003cp\u003e(a)\u0026nbsp; \u003cem\u003eP\u003c/em\u003e-\u003cem\u003eE\u003c/em\u003e loops under different electric fields and (b) the corresponding energy-storage properties of the 0.88NN-0.12BF + 1 wt.% MnO\u003csub\u003e2\u003c/sub\u003e ceramics\u003c/p\u003e","description":"","filename":"floatimage9.png","url":"https://assets-eu.researchsquare.com/files/rs-8894516/v1/fd8168c4925a5a6f49edfc54.png"},{"id":103505329,"identity":"e39998df-6252-4f64-909e-558d8f5249cc","added_by":"auto","created_at":"2026-02-26 13:30:01","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":104265,"visible":true,"origin":"","legend":"\u003cp\u003e(a) The temperature dependence of dielectric permittivity and loss for 0.88NN-0.12BF + 1 wt.% MnO\u003csub\u003e2\u003c/sub\u003e ceramics. (b) The measured complex AC impedance data for 0.88NN-0.12BF + 1 wt.% MnO\u003csub\u003e2\u003c/sub\u003e ceramics at 500 ℃.\u003c/p\u003e","description":"","filename":"floatimage10.png","url":"https://assets-eu.researchsquare.com/files/rs-8894516/v1/2731673f8daa7c9a05724243.png"},{"id":103217888,"identity":"dad4da82-27e0-4534-9048-7d206d66ed22","added_by":"auto","created_at":"2026-02-23 09:51:05","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":87950,"visible":true,"origin":"","legend":"\u003cp\u003e(a)The distribution of the electric field simulated for the MnFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/0.88NN-0.12BF-Mn\u0026nbsp; composite ceramic at 200 kV/cm. (b) Schematic illustration of the built-in electric field formed by the semiconductor captured electrons.\u003c/p\u003e","description":"","filename":"floatimage11.png","url":"https://assets-eu.researchsquare.com/files/rs-8894516/v1/b24c45dcb1a542c08864b3d6.png"},{"id":103509699,"identity":"a523cc66-d7c5-4f93-a97a-0420f61959de","added_by":"auto","created_at":"2026-02-26 14:00:36","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2880147,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8894516/v1/39d9b97a-035f-4e4f-8d0f-0e9c92c136eb.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Self-generated semiconductor/relaxor antiferroelectric composite ceramics with high energy storage properties","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eAs a kind of electric energy storage mode, ceramic based dielectric energy storage capacitor is the core part of many pulse power electronic systems, including pulse power weapons, power distribution devices, electric vehicles and other fields \u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003e. At present, the requirements of miniaturization, integration and low power consumption for dielectric energy storage capacitors are put forward in the related military and civil fields, and the evolution of dielectric materials with higher energy storage characteristics becomes the key to meet the current needs \u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e8\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003eUsually, the energy storage parameters of ceramic capacitors can be easily obtained by calculating the integral of the polarization electric field (\u003cem\u003eP\u003c/em\u003e-\u003cem\u003eE\u003c/em\u003e) hysteresis loop, as shown below:\u003c/p\u003e\n\u003cp\u003e\u003cimg 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\"\u003e\u003c/p\u003e\n\u003cp\u003ewhere \u003cem\u003eE\u003c/em\u003e is the the electric field, \u003cem\u003eP\u003c/em\u003e\u003csub\u003emax\u003c/sub\u003e is the saturated polarization, and \u003cem\u003eP\u003c/em\u003e\u003csub\u003er\u003c/sub\u003e is the remanent polarization. Based on the above formula, we can design a new type of ceramic capacitor with high energy storage performance, which should simultaneously meet the requirements of high breakdownstrength, large \u003cem\u003eP\u003c/em\u003e\u003csub\u003emax\u003c/sub\u003e and low \u003cem\u003eP\u003c/em\u003e\u003csub\u003er\u003c/sub\u003e. It is evident that under the applied electric fields, when \u003cem\u003eP\u003c/em\u003e\u003csub\u003emax\u003c/sub\u003e is large but \u003cem\u003eP\u003c/em\u003e\u003csub\u003er\u003c/sub\u003e is at its minimum, \u003cem\u003eW\u003c/em\u003e\u003csub\u003erec\u003c/sub\u003e can be greatly enhanced. Antiferroelectric ceramics are one of the most important ceramic capacitors developed to date due to their higher energy storage density than ferroelectric and linear ceramics, as well as their high \u003cem\u003eP\u003c/em\u003e\u003csub\u003emax\u003c/sub\u003e, low \u003cem\u003eP\u003c/em\u003e\u003csub\u003er\u003c/sub\u003e, and moderate breakdown strength \u003cem\u003eE\u003c/em\u003e\u003csub\u003eb\u003c/sub\u003e\u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e8\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003eThe energy storage performance of various types of AFE ceramics have been studied, including lead based and lead-free solid solutions. The \u003cem\u003eW\u003c/em\u003e\u003csub\u003erec\u003c/sub\u003e values of (Pb,La)(Zr,Sn,Ti)O\u003csub\u003e3\u003c/sub\u003e, and AgNbO\u003csub\u003e3\u003c/sub\u003e AFE ceramics are 5.56 J/cm\u003csup\u003e3\u003c/sup\u003e and 4.4 J/cm\u003csup\u003e3\u003c/sup\u003e, respectively\u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e16\u003c/span\u003e]\u003c/sup\u003e. However, due to the large hysteresis between AFE-FE and FE-AFE phase transitions, normal AFE ceramics with macroscopic domains typically display typical double \u003cem\u003eP\u003c/em\u003e-\u003cem\u003eE\u003c/em\u003e hysteresis loops, resulting in relatively low energy storage efficiency\u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e16\u003c/span\u003e]\u003c/sup\u003e. Meanwhile, considering the harmful effects of lead oxide on the human health and environment, lead-free AFE ceramics have received more attention in recent years \u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e17\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e29\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003eNaNbO\u003csub\u003e3\u003c/sub\u003e(NN)-based ceramics have become attractive lead-free antiferroelectric ceramics due to their complex phase transitions and enormous potential as a substitute for lead based materials \u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e30\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e31\u003c/span\u003e]\u003c/sup\u003e. Pure NaNbO\u003csub\u003e3\u003c/sub\u003e ceramics belong to the AFE orthogonal P phase (Pbma space group) at 25℃, and exhibit AFE orthogonal R phase (Pnma space group) when heated at approximately 360 \u0026deg; C. Nevertheless, due to the irreversible phase transition from AFE to FE induced by an external electric field, pure NaNbO\u003csub\u003e3\u003c/sub\u003e ceramics should exhibit poor energy storage performance \u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e32\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e35\u003c/span\u003e]\u003c/sup\u003e. Recent researches have shown that by adding ABO\u003csub\u003e3\u003c/sub\u003e perovskite compound, repeatable double \u003cem\u003eP\u003c/em\u003e-\u003cem\u003eE\u003c/em\u003e curves can be achieved in NaNbO\u003csub\u003e3\u003c/sub\u003e-based ceramics. This should enhance the potential application of this ceramic material in energy storage capacitors \u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e36\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e40\u003c/span\u003e]\u003c/sup\u003e. For example, it has been reported that CaZrO\u003csub\u003e3\u003c/sub\u003e can stabilize the AFE P phase, increase the \u003cem\u003eW\u003c/em\u003e\u003csub\u003erec\u003c/sub\u003e and \u003cem\u003e\u0026eta;\u003c/em\u003e of NaNbO\u003csub\u003e3\u003c/sub\u003e ceramics to about 0.55 J/cm\u003csup\u003e3\u003c/sup\u003e and 63%, while Na\u003csub\u003e0.5\u003c/sub\u003eBi\u003csub\u003e0.5\u003c/sub\u003eTiO\u003csub\u003e3\u003c/sub\u003e has been reported to promote the formation of AFE R phase at room temperature, achieving good energy storage performance (\u003cem\u003eW\u003c/em\u003e\u003csub\u003erec\u003c/sub\u003e of 12 J/cm\u003csup\u003e3\u003c/sup\u003e, and \u003cem\u003e\u0026eta;\u003c/em\u003e of 70%) \u003csup\u003e[35,36.38]\u003c/sup\u003e. In brief, NaNbO\u003csub\u003e3\u003c/sub\u003e based ceramics with AFE R phase (also known as NaNbO\u003csub\u003e3\u003c/sub\u003e based relaxor antiferroelectric ceramics) have relatively low hysteresis \u003cem\u003eP\u003c/em\u003e-\u003cem\u003eE\u003c/em\u003e loops, indicating higher energy storage performance \u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e37\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e40\u003c/span\u003e]\u003c/sup\u003e. Moreover, the effect of a small amount of transition-metal oxides addition on the energy storage performance of 0.92NaNbO\u003csub\u003e3\u003c/sub\u003e-0.08Bi(Mg\u003csub\u003e0.5\u003c/sub\u003eTi\u003csub\u003e0.5\u003c/sub\u003e)O\u003csub\u003e3\u003c/sub\u003e (0.92NN-0.08BMT) relaxor antiferroelectric ceramics was also studied. For example, doping 0.5 mol% MnO\u003csub\u003e2\u003c/sub\u003e, CuO and CeO\u003csub\u003e2\u003c/sub\u003e can significantly improve the behaviour, defect structure and bulk resistivity of 0.92NN-0.08BMT ceramics, thus greatly improving the breakdown strength. As a result, both high \u003cem\u003eW\u003c/em\u003e\u003csub\u003erec\u003c/sub\u003e of 5.57 J/cm\u003csup\u003e3\u003c/sup\u003e and \u003cem\u003e\u0026eta;\u003c/em\u003e of 71% under 480 kV/cm were achieved in NN-BMT-Mn ceramic \u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e41\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003eBiFeO\u003csub\u003e3\u003c/sub\u003e (BF) has a strong polarization ability and a perovskite structure similar to Na\u003csub\u003e0.5\u003c/sub\u003eBi\u003csub\u003e0.5\u003c/sub\u003eTiO\u003csub\u003e3\u003c/sub\u003e (NBT) \u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e18\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e20\u003c/span\u003e]\u003c/sup\u003e. It is expected that BF can combined with NN to form a solid solution structure and enhance the energy storage performance of NN. In this research, the energy storage performance of NN ceramics has been improved by introducing BF to NN. As expected, 0.88NaNbO\u003csub\u003e3\u003c/sub\u003e-0.12BiFeO\u003csub\u003e3\u003c/sub\u003e (0.88NN-0.12BF) ceramic represents comprehensive advantages of high \u003cem\u003eW\u003c/em\u003e\u003csub\u003erec\u003c/sub\u003e of 7.4 J/cm\u003csup\u003e3\u003c/sup\u003e, high \u003cem\u003e\u0026eta;\u003c/em\u003e of 83.4%, excellent frequency stability of 1-100 Hz and wide temperature range of 25ཞ125 ℃. Besides, as a typical multivalent element, Mn forms various valence ions during sintering process to generate multiple impacts on ceramics, including pinning ferroelectric domain, enhancing densification, etc\u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e21\u003c/span\u003e]\u003c/sup\u003e. Hence, Mn has been considered as one of the most effective elements for improving energy storage performance, and it\u0026rsquo;s effectiveness has been confirmed by many studies\u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e41\u003c/span\u003e]\u003c/sup\u003e. In this paper, the MnO\u003csub\u003e2\u003c/sub\u003e doped 0.88NN-0.12BF ceramics were prepared. The influences of Mn doping on energy storage properties have been discussed. Specially, when 1 wt.% was added to the 0.88NN-0.12BF ceramic, we found that MnO\u003csub\u003e2\u003c/sub\u003e was not completely absorbed by the main lattice. Some Mn ions enter into the lattice to replace Fe ions, while the precipitated Fe ions react with MnO\u003csub\u003e2\u003c/sub\u003e to form a second phase of semiconductor MnFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e. As a result, the defect structure, bulk resistivity and dielctric loss were improved, thus greatly improving dielectric breakdown strength, and further reduced residual polarization and hysteresis. The orthorhombic antiferroelectric R phase and semiconductor phase synergistically benefit to the extremely large \u003cem\u003eW\u003c/em\u003e\u003csub\u003erec\u003c/sub\u003e of 14.3 J/cm\u003csup\u003e3\u003c/sup\u003eand very high \u003cem\u003e\u0026eta;\u003c/em\u003e\u0026thinsp;=\u0026thinsp;88.7% at 700 kV/cm.\u003c/p\u003e"},{"header":"2. Experiment","content":"\u003cp\u003eCeramic powders of (1-\u003cem\u003ex\u003c/em\u003e)NaNbO\u003csub\u003e3\u003c/sub\u003e-\u003cem\u003ex\u003c/em\u003eBiFeO\u003csub\u003e3\u003c/sub\u003e (\u003cem\u003ex\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.04\u0026ndash;0.16) were synthetized by the solid-state reaction process. Powders of Na\u003csub\u003e2\u003c/sub\u003eCO\u003csub\u003e3\u003c/sub\u003e (99.8%, Sigma-Aldrich), Nb\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003e (99.8%, Alfa-Aesar), Bi\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e (99.5%, Sigma-Aldrich) and Fe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e(99.5%, Sigma-Ald rich) were used as raw materials. The chemical stoichiometry amounts of the powder will be measured based on each composition formula. Subsequently, the mixture was ball milled with ethanol and zirconia balls in nylon pots for 12 hours. Then dry the slurry in the air. The mixed powder is poured into a crucible, and calcined at 750\u0026deg;C for 2 hours, followed by calcination at 850\u0026deg;C for 2 hours. The calcined powder was ball milled again for 8 hours to obtain uniform particle siz, dried and uniaxially pressed into pellets. The NaNbO\u003csub\u003e3\u003c/sub\u003e ceramics were sintered at 1350\u0026deg;C for 3 hours, while all NN-BF pellets were sintered at 1180\u0026deg;C for 3 hours to achieve densification. It is worth noting that these samples need to be embedded in the calcined powder to prevent the evaporation of sodium and bismuth elements during the sintering process.\u003c/p\u003e \u003cp\u003eThe density of sintered ceramic samples was tested according to Archimedes principle. The microstructure was characterized by field-emission scanning electron microscope (FE-SEM, Hitachi S4800, Tokyo, Japan). The samples were polished and thermally etched at 1000\u0026ndash;1050 ℃ for 0.5 h before testing. The valence states of Na, Nb, Bi, Fe, O and Mn in MnO\u003csub\u003e2\u003c/sub\u003e doped 0.88NN-0.12BF sample powders were determined by means of X-ray photoelectron spectroscopy (XPS, PHI 5000Versa probe, Japan) equipped with an Al-Kα with energy of =\u0026thinsp;1486.6 eV, in which binding energies were corrected to the C 1s signal at 284.6 eV from adventitious carbon. Before XPS testing, the sample should be dried under vacuum for 12 hours to prevent the influence of adsorbed H\u003csub\u003e2\u003c/sub\u003eO. The crystallographic structures of sintered samples were measured by powder X-ray diffraction (XRD, PANalyticals, Cambridge, UK). Data from the XRD were analyzed by the rietveld method using the GSAS. Silver paste (Youleguang photoelectric technology co., LTD., SA-6131, Wuhan, China) was evenly covered on the top and bottom of discs, and then fired at 550\u0026deg;C for 30 min to obtain dense and smooth electrodes for electric testing. Frequency and temperature dependences of dielectric constant (ε\u003csub\u003er\u003c/sub\u003e) and loss(tan δ) were tested at the temperature range of -160 to 200 ◦C at 0.1, 1, 5, 10, 100 and 500 kHz using an LCR meter (Julang technology co., Ltd,, TZDM-RT-600, Haerbin, China). The impedance spectroscopy were performed by using an LCR meter (Tonghui Electronic Co., Ltd,, TH2382, Changzhou, China) during heating. The electric field-induced polarization (\u003cem\u003eP\u003c/em\u003e-\u003cem\u003eE\u003c/em\u003e) were characterized by using the ferroelectric measuring system (aix ACCT Co., Aachen, Germany).\u003c/p\u003e"},{"header":"3. Results and discussion","content":"\u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e(a) and (c) illustrates the bipolar and unipolar \u003cem\u003eP\u003c/em\u003e-\u003cem\u003eE\u003c/em\u003e loops of (1-\u003cem\u003ex\u003c/em\u003e)NN-\u003cem\u003ex\u003c/em\u003eBF ceramics measured at 300 kV/cm and 10 Hz, respectively. Accompanying the composition induced phase transition, an obvious change in the \u003cem\u003eP\u003c/em\u003e-\u003cem\u003eE\u003c/em\u003e curves can be found. The \u003cem\u003ex\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.04, 0.06 and 0.08 samples display reversible square-like double \u003cem\u003eP\u003c/em\u003e-\u003cem\u003eE\u003c/em\u003e loops with large polarization hysteresis, corresponding to high \u003cem\u003eP\u003c/em\u003e\u003csub\u003er\u003c/sub\u003e values, leading a poor energy-storage properties in these orthorhombic P phase (Pbma) phase compositions, as indicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e(d). As \u003cem\u003ex\u003c/em\u003e increases from 0.08 to 0.16, double square \u003cem\u003eP\u003c/em\u003e-\u003cem\u003eE\u003c/em\u003e curves gradually transform into slim curves with near-zero \u003cem\u003eP\u003c/em\u003e\u003csub\u003er\u003c/sub\u003e. These slim curves were formed due to the significantly enhanced dielectric relaxation characteristics of the AFE orthorhombic R phase (Pnma), resulting in a signicantly increased phase transition and a rapid polarization response\u003csup\u003e[\u003cspan additionalcitationids=\"CR43 CR44 CR45 CR46 CR47 CR48 CR49 CR50\" citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e]\u003c/sup\u003e. Figure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e(b) shows the variations in \u003cem\u003eP\u003c/em\u003e\u003csub\u003emax\u003c/sub\u003e, \u003cem\u003eP\u003c/em\u003e\u003csub\u003er\u003c/sub\u003e, and \u003cem\u003eΔP\u003c/em\u003e (\u003cem\u003eP\u003c/em\u003e\u003csub\u003emax\u003c/sub\u003e-\u003cem\u003eP\u003c/em\u003e\u003csub\u003er\u003c/sub\u003e) for NN-BF ceramics. The \u003cem\u003eΔP\u003c/em\u003e first increases and then decreases when \u003cem\u003ex\u003c/em\u003e is in the range of 0.06\u0026ndash;0.16, indicating that BF doping enhences the relaxor characteristics of the NN-BF, resulting in an increase in \u003cem\u003eΔP\u003c/em\u003e. The large \u003cem\u003eΔP\u003c/em\u003e value is favorable to improve the energy storage performance. As a result, obviously improved energy storage performance of large \u003cem\u003eW\u003c/em\u003e\u003csub\u003erec\u003c/sub\u003e = 2.93 J/cm\u003csup\u003e3\u003c/sup\u003e and 3.32 J/cm\u003csup\u003e3\u003c/sup\u003e and desirable \u003cem\u003eη\u0026thinsp;=\u003c/em\u003e\u0026thinsp;81.5% and 88.5% were obtained in \u003cem\u003ex\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.10 and 0.12 ceramics at 300 kV/cm, respectively, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e(d), exhibiting obvious advantages of the AFE R phase over the AFE P phase.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e(a) and (b) show the temperature dependence of relative dielectric constant and loss tangent of (1-\u003cem\u003ex\u003c/em\u003e)NaNbO\u003csub\u003e3\u003c/sub\u003e-\u003cem\u003ex\u003c/em\u003eBiFeO\u003csub\u003e3\u003c/sub\u003e ceramics at 1, 10, 100 and 500 kHz. The 0.90NN-0.10BF and 0.88NN-0.12BF samples both show obvious dielectric relaxation characteristics. They belong to AFE orthorhombic R phase. When BF is dissolved in NN, the existence of Bi\u003csup\u003e3+\u003c/sup\u003e, Fe\u003csup\u003e3+\u003c/sup\u003e, and A-site vacancies whose charges and radii are different from the host ions Na\u003csup\u003e+\u003c/sup\u003e and Nb\u003csup\u003e5+\u003c/sup\u003e are in charge of breaking the long-range FE ordering and resulted in the relaxor characteristics. It can be observed that the degree of dielectric relaxation raises from 0.90NN-0.10BF to 0.88NN-0.12BF, mainly manifested by the reduce of the temperature at the maximum dielectric permittivity (\u003cem\u003eT\u003c/em\u003e\u003csub\u003em\u003c/sub\u003e) and the increase of the relaxation factor \u003cem\u003eΔT\u003c/em\u003e\u003csub\u003erelax\u003c/sub\u003e (=\u0026thinsp;\u003cem\u003eT\u003c/em\u003e\u003csub\u003em\u003c/sub\u003e, \u003csub\u003e0.5 MHz\u003c/sub\u003e - \u003cem\u003eT\u003c/em\u003e\u003csub\u003em\u003c/sub\u003e, \u003csub\u003e1 kHz\u003c/sub\u003e). The occurrence of dielectric relaxor phenomenon is often referred to the improved random fields caused by the local composition disorder \u003csup\u003e[\u003cspan additionalcitationids=\"CR43 CR44\" citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e(c) and (d) show the XRD patterns of the 0.90NN-0.10BF and 0.88NN-0.12BF ceramics, respectively. The results showed a typical perovskite structure, and no obvious second phases appear. All the peaks display an orthorhombic phase structure at room temperature. Rietveld refinement is completed by a single-phase refinement approach (\u003cem\u003epnma\u003c/em\u003e) in the GSAS2. The R\u003csub\u003ewp\u003c/sub\u003e is 2.7% and 2.8, respectively. The data showed that the Bi\u003csup\u003e3+\u003c/sup\u003e has taken the place of the A-site Na\u003csup\u003e+\u003c/sup\u003e in the matrix of two crystallographic sites; meanwhile, the B-site Nb\u003csup\u003e5+\u003c/sup\u003e (0.64 \u0026Aring;) was replaced by Fe\u003csup\u003e3+\u003c/sup\u003e (0.605 \u0026Aring;). Compared with pure NaNbO\u003csub\u003e3\u003c/sub\u003e ceramics, the calculated unit cell parameters (a\u0026thinsp;=\u0026thinsp;5.54 \u0026Aring;, b\u0026thinsp;=\u0026thinsp;8.38 \u0026Aring;, c\u0026thinsp;=\u0026thinsp;5.53 \u0026Aring;) and (a\u0026thinsp;=\u0026thinsp;5.54 \u0026Aring;, b\u0026thinsp;=\u0026thinsp;7.82 \u0026Aring;, c\u0026thinsp;=\u0026thinsp;5.52 \u0026Aring;) show little change. Due to the low goodness value of χ\u003csup\u003e2\u003c/sup\u003e and R\u003csub\u003ewp\u003c/sub\u003e, it proves the reliability of the fitting with the cubic model.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eStructural parameters of rietveld refinement of orthorhombic phase (\u003cem\u003epnma\u003c/em\u003e) for 0.90NN-0.10BF and 0.88NN-0.12BF.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSamples\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStructures and parameters of\u003c/p\u003e \u003cp\u003eunit cell (\u0026Aring;)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eFitting parameters\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e0.90NN-0.10BF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ea\u0026thinsp;=\u0026thinsp;5.54 (\u0026Aring;); b\u0026thinsp;=\u0026thinsp;8.38(\u0026Aring;); c\u0026thinsp;=\u0026thinsp;5.53 (\u0026Aring;)\u003c/p\u003e \u003cp\u003eα\u0026thinsp;=\u0026thinsp;β\u0026thinsp;=\u0026thinsp;γ\u0026thinsp;=\u0026thinsp;90\u0026deg;\u003c/p\u003e \u003cp\u003eVolume\u0026thinsp;=\u0026thinsp;242.4 (\u0026Aring;\u003csup\u003e3\u003c/sup\u003e)\u003c/p\u003e\u003cp\u003eρ\u0026thinsp;=\u0026thinsp;4.98 g/cm\u003csup\u003e3\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eχ\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;2.134\u003c/p\u003e \u003cp\u003eR\u003csub\u003ewp\u003c/sub\u003e = 0.027\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e0.88NN-0.12BF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ea\u0026thinsp;=\u0026thinsp;5.54 (\u0026Aring;); b\u0026thinsp;=\u0026thinsp;7.82 (\u0026Aring;);c\u0026thinsp;=\u0026thinsp;5.52(\u0026Aring;);\u003c/p\u003e \u003cp\u003eα\u0026thinsp;=\u0026thinsp;β\u0026thinsp;=\u0026thinsp;γ\u0026thinsp;=\u0026thinsp;90\u0026deg;\u003c/p\u003e \u003cp\u003eVolume\u0026thinsp;=\u0026thinsp;239.3 (\u0026Aring;\u003csup\u003e3\u003c/sup\u003e)\u003c/p\u003e\u003cp\u003eρ\u0026thinsp;=\u0026thinsp;5.007 g/cm\u003csup\u003e3\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eχ\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;2.123\u003c/p\u003e \u003cp\u003eR\u003csub\u003ewp\u003c/sub\u003e = 0.028\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e displays the SEM images of (1-\u003cem\u003ex\u003c/em\u003e)NaNbO\u003csub\u003e3\u003c/sub\u003e-\u003cem\u003ex\u003c/em\u003eBiFeO\u003csub\u003e3\u003c/sub\u003e ceramics. The samples of 0.90NN-0.10BF and 0.88NN-0.12BF exhibit homogenous and dense microstructure with an average grain size of 4.1 \u0026micro;m and 4.4 \u0026micro;m, respectively. The relative density of 0.90NN-0.10BF and 0.88NN-0.12BF is about 97%.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e (a) and (b) gives the unipolar \u003cem\u003eP\u003c/em\u003e-\u003cem\u003eE\u003c/em\u003e loops of (1-\u003cem\u003ex\u003c/em\u003e)NaNbO\u003csub\u003e3\u003c/sub\u003e-\u003cem\u003ex\u003c/em\u003eBiFeO\u003csub\u003e3\u003c/sub\u003e ceramics under different electric fields at room temperature and 10 Hz. The 0.90NN-0.10BF samples exhibit high polarization hysteresis, corresponding to high \u003cem\u003eP\u003c/em\u003e\u003csub\u003er\u003c/sub\u003e values. Therefore, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e(c), the energy storage performance in these AFE R phase compositions is poor. An significantly slim \u003cem\u003eP\u003c/em\u003e-\u003cem\u003eE\u003c/em\u003e loop can be achieved in 0.88NN-0.12BF ceramic. These slender curves were generated due to significantly increased dielectric relaxation features of the AFE R phase, leading to a rapid polarization response and obviously enhanced phase transition \u003csup\u003e[\u003cspan additionalcitationids=\"CR47 CR48\" citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e\u003c/sup\u003e]. This is very consistent with the analysis result in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e(b). Therefore, adding BF can availably raise the stability of the AFE phase in NN. As a result, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e(d), obviously improved energy storage properties of \u003cem\u003eW\u003c/em\u003e\u003csub\u003erec\u003c/sub\u003e = 7.6 J cm\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e and \u003cem\u003eη\u003c/em\u003e\u0026thinsp;=\u0026thinsp;83.4% were achieved in 0.88NN-0.12BF ceramics under 500 kV/cm, showing outstanding advantages of the AFE R phase over the AFE P phase.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe temperature stability of unipolar \u003cem\u003eP\u003c/em\u003e-\u003cem\u003eE\u003c/em\u003e loops and energy storage performance for 0.88NN-0.12BF ceramic from 25\u0026deg;C to 125\u0026deg;C at \u003cem\u003eE\u003c/em\u003e\u0026thinsp;=\u0026thinsp;300 kV/cm at 10Hz are displayed in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e (a) and (b). The \u003cem\u003eP-E\u003c/em\u003e loop shows an excellent temperature stability when the temperature rises, are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e (a), which may be beneficial for the stability of the AFE R phase coexisting in 0.88NN-0.12BF ceramics over a wide temperature range. Thus, \u003cem\u003eW\u003c/em\u003e\u003csub\u003erec\u003c/sub\u003e only reduced from 3.39 J/cm\u003csup\u003e3\u003c/sup\u003e to 3.26 J/cm\u003csup\u003e3\u003c/sup\u003e, which is a decrease of about 3.8% between 25℃ and 125 ℃. The excellent temperature stability of \u003cem\u003eW\u003c/em\u003e\u003csub\u003e\u003cem\u003erec\u003c/em\u003e\u003c/sub\u003e indicates that 0.88NN-0.12BF ceramic is a promising lead-free AFE relaxor suitable for high-temperature dielectric capacitors. Besides, the frequency stability of unipolar \u003cem\u003eP\u003c/em\u003e-\u003cem\u003eE\u003c/em\u003e and \u003cem\u003eW\u003c/em\u003e\u003csub\u003erec\u003c/sub\u003e is studied, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e(c) and (d). This results display that \u003cem\u003eW\u003c/em\u003e\u003csub\u003erec\u003c/sub\u003e increases slightly with the frequency increases. The \u003cem\u003eW\u003c/em\u003e\u003csub\u003erec\u003c/sub\u003e in creased from 3.25 J/cm\u003csup\u003e3\u003c/sup\u003e to 3.46 J/cm\u003csup\u003e3\u003c/sup\u003e, which indicates it reduced by only 6.5% between 0.1 Hz and 500 Hz, indicating that 0.88NN-0.12BF ceramics have excellent frequency stability. The dispersion characteristics of relaxor AFE are associated with the orientation and fragmentation mechanism of nanodomains in low-voltage cycles, indicating that these processes are time-dependent due to the assumed dynamics \u003csup\u003e[\u003cspan additionalcitationids=\"CR51 CR52 CR53 CR54\" citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e55\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eIn order to further optimize the energy storage performance, the composition with \u003cem\u003ex\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.12 was doped with 0.5, 1 and 2 wt.% MnO\u003csub\u003e2\u003c/sub\u003e. The SEM images at backscattered electrons (BSE) mode of polished and thermally etched MnO\u003csub\u003e2\u003c/sub\u003e doped NN-BF ceramics are presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e(a)-(d). All specimens were well densified with only a few pores. When 0.5wt.% MnO\u003csub\u003e2\u003c/sub\u003e is added, the grain size slightly decreases and the uniformity is improved. Increasing the MnO\u003csub\u003e2\u003c/sub\u003e content to 1 wt.%, the presence of a second phase was discovered. Continuing to add up to 2 wt.%, it was found that the second phase still existed and had a larger quantity. Figure\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e(e) exhibits the unipolar \u003cem\u003eP\u003c/em\u003e-\u003cem\u003eE\u003c/em\u003e loops of MnO\u003csub\u003e2\u003c/sub\u003e doped 0.88NN-0.12BF ceramics measured at maximum breakdown electric field and 10 Hz. The \u003cem\u003eE\u003c/em\u003e\u003csub\u003eb\u003c/sub\u003e varied evidently when MnO\u003csub\u003e2\u003c/sub\u003e was added, so all measurements were measured at the optimal electric field rather than an identical one. All \u003cem\u003eP\u003c/em\u003e-\u003cem\u003eE\u003c/em\u003e loops displayed similar features, manifesting as a relatively slim shape and small \u003cem\u003eP\u003c/em\u003e\u003csub\u003er\u003c/sub\u003e. As seen from Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e(f), adding 0.5 wt.% MnO\u003csub\u003e2\u003c/sub\u003e to NN-12BF, the breakdown electric field has a slight improvement, and no second phase was found (see Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e(b)). The \u003cem\u003eE\u003c/em\u003e\u003csub\u003eb\u003c/sub\u003e, \u003cem\u003eW\u003c/em\u003e\u003csub\u003erec\u003c/sub\u003e \u003cem\u003eη\u003c/em\u003e and value significantly increased when 1.0 wt% MnO\u003csub\u003e2\u003c/sub\u003e was applied, the second phase was observed (see Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e(c)). This indicates that the generation of the second phase has a significant impact on the energy storage performance of the material system. However, adding 2 wt% MnO\u003csub\u003e2\u003c/sub\u003e can lead to a sharp decrease in breakdown field strength, which may be related to the content of the second phase (see Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e(d)). Overall, a appropriate amount of MnO\u003csub\u003e2\u003c/sub\u003e addition can form a composite ceramic structure, which can effectively improve the breakdown field strength, thus enhancing energy storage performance.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eIn order to further understand the chemical composition of the second phase. Energy Dispersive Spectrometer (EDS) measurement was carried out. The SEM pictures of the fracture surface of thermal etching at backscattered electron (BSE) mode and the distribution of two-dimensional elements in the 0.88NN-0.12BF\u0026thinsp;+\u0026thinsp;1 wt.% MnO\u003csub\u003e2\u003c/sub\u003e ceramic are presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e (a). It can be observed that some dark and small grains arelocated in the gaps between larger grains. By using two-dimensional distribution and corresponding mapping of element were used to characterize it, the composite microstructure of 0.88NN-0.12BF\u0026thinsp;+\u0026thinsp;1 wt.% MnO\u003csub\u003e2\u003c/sub\u003e ceramic can be intuitively displayed. It can be observed that the chemical composition of this ceramic sample is uneven, because Na, Nb and Bi occupy the same area and are interconnected. A small amount of Fe, Mn and O occupies the same area as Na, Bi and Nb, and a large amounts of Fe, Mn and O occupies the isolated and remaining areas. This proves that the main grains are ascribed to 0.88NaNbO\u003csub\u003e3\u003c/sub\u003e-0.12Bi(Fe\u003csub\u003e1\u0026minus;\u003cem\u003ey\u003c/em\u003e\u003c/sub\u003eMn\u003csub\u003e\u003cem\u003ey\u003c/em\u003e\u003c/sub\u003e)O\u003csub\u003e3\u003c/sub\u003e (abbreviated as 0.88NN-0.12BF-Mn), while the second phase grains are consist of Fe, Mn and O elements. That is to say, after adding 1% MnO\u003csub\u003e2\u003c/sub\u003e, Mn\u003csup\u003e4+\u003c/sup\u003e ions enter the main crystal phase of NN-12BF and replace Fe\u003csup\u003e3+\u003c/sup\u003e ions. The precipitated Fe\u003csup\u003e3+\u003c/sup\u003e ions react with the remaining MnO\u003csub\u003e2\u003c/sub\u003e to form the second phase. This second phase grains are mainly embedded in the boundaries of the 0.88NN-0.12BF-Mn, achieving a 0\u0026ndash;3 type composite ceramic.Then we analyzed the their EDS point analysis spectrum, and the molar ratios of elements were obtained (see Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e(b)). The composition values of the second phase were determined by EDS can be written approximately as Mn\u003csub\u003e0.141\u003c/sub\u003eFe\u003csub\u003e0.247\u003c/sub\u003eO\u003csub\u003e0.612\u003c/sub\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eTo further confirm the crystal structure of the second phase more accurately. The XRD pattern of the sintered 0.88NN-0.12BF\u0026thinsp;+\u0026thinsp;1 wt.% MnO\u003csub\u003e2\u003c/sub\u003e ceramic powders was tested. The result indicates the NN-12BF-Mn major crystal phase is perovskite structure, and it exhibits an orthorhombic phase at RT. More importantly, MnFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e semiconductor phase was detected (see Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e). The rietveld renement results are summarized in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. The composite ceramic sample consists of 98.6 wt.% 0.88NN-0.12BF-Mn and 1.4 wt.% MnFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e. The unit cell parameters of 0.88NN-0.12BF-Mn are : a\u0026thinsp;=\u0026thinsp;5.54 \u0026Aring;, b\u0026thinsp;=\u0026thinsp;7.82 \u0026Aring;, c\u0026thinsp;=\u0026thinsp;5.53 \u0026Aring;.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eStructural parameters of rietveld refinement of orthorhombic phase (\u003cem\u003epnma\u003c/em\u003e) for 0.88NN-0.12BF\u0026thinsp;+\u0026thinsp;1 wt.% MnO\u003csub\u003e2\u003c/sub\u003e ceramics\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eComposition of\u003c/p\u003e \u003cp\u003esamples\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePhase fraction\u003c/p\u003e \u003cp\u003e(wt.%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eStructures and parameters of\u003c/p\u003e \u003cp\u003eunit cell (\u0026Aring;)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e0.88NN-0.12BF-Mn\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e98.6%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ea\u0026thinsp;=\u0026thinsp;5.54 (\u0026Aring;); b\u0026thinsp;=\u0026thinsp;7.82 (\u0026Aring;); c\u0026thinsp;=\u0026thinsp;5.53 (\u0026Aring;)\u003c/p\u003e \u003cp\u003eα = β = γ =90\u0026deg;\u003c/p\u003e \u003cp\u003eVolume\u0026thinsp;=\u0026thinsp;239.4 (\u0026Aring;\u003csup\u003e3\u003c/sup\u003e)\u003c/p\u003e\u003cp\u003eρ = 4.98 g/cm\u003csup\u003e3\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMnFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.4%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e(a) presents \u003cem\u003eP\u003c/em\u003e-\u003cem\u003eE\u003c/em\u003e loops of MnFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/0.88NN-0.12BF-Mn semiconductor/relaxor antiferroelectric composite ceramic measured in different applied electric field under the room temperature. Obviously, the \u003cem\u003eP\u003c/em\u003e\u003csub\u003emax\u003c/sub\u003e increases monotonously with the increase of electric field up to 700 kV /cm, and a low-hysteresis \u003cem\u003eP\u003c/em\u003e-\u003cem\u003eE\u003c/em\u003e curves with \u003cem\u003eP\u003c/em\u003e\u003csub\u003er\u003c/sub\u003e ~ 0 \u0026micro;C/cm\u003csup\u003e2\u003c/sup\u003e can be measured within the studied electric field range, resulting in an ultra-high \u003cem\u003eW\u003c/em\u003e\u003csub\u003erec\u003c/sub\u003e of 13.4 J/cm\u003csup\u003e3\u003c/sup\u003e and a desirable \u003cem\u003eη\u003c/em\u003e of 87.4%. Compared with pure 0.88NN-0.12BF ceramic, the breakdown strength \u003cem\u003eE\u003c/em\u003e\u003csub\u003eb\u003c/sub\u003e and \u003cem\u003eW\u003c/em\u003e\u003csub\u003erec\u003c/sub\u003e of MnFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/0.88NN-0.12BF-Mn composite ceramic are significantly improved by 40% and 78%, respectively.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e (a) shows the variation of permittivity \u003cem\u003eε\u003c/em\u003e\u003csub\u003e\u003cem\u003er\u003c/em\u003e\u003c/sub\u003e and dielectric loss tanδ of MnFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/0.88NN-0.12BF-Mn semiconductor/relaxor composite ceramics with temperature at different frequencies. Compared with pure 0.88NN-0.12BF ceramic, the dielectric relaxation degree MnFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/0.88NN-0.12BF-Mn semiconductor/relaxor composite ceramic are further improved, and the dielectric constant greatly decreases in the whole temperature range. Impedance spectroscopy is an excellent tool for studying dielectric relaxation and electrical conduction mechanisms. The Z\u0026prime;- Z\u0026prime;\u0026prime; curves of different samples achieved at 500\u0026deg;C in the frequency range of 20 Hz to 1 MHz, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e(b), where Z\u0026prime; and Z\u0026prime;\u0026prime; mean the real and imaginary parts of impedance, respectively. The results show that all of the 0.88NN-0.12BF and 0.88NN-0.12BF\u0026thinsp;+\u0026thinsp;1 wt% MnO\u003csub\u003e2\u003c/sub\u003e ceramics present a nearly single impedance arc. These arcs were found to be unable to be fitted by an RC equivalent circuit. This result shows that both grains and grain boundaries contribute significantly to impedance. As shown in the illustration of Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e(b), in order to divide the respective contributions of grain boundaries and grains, an equivalent simulation circuit can be constructed for fitting.\u003c/p\u003e \u003cp\u003eThis circuit consists of a series of grain boundaries and grains components, including grain boundary capacitance (C\u003csub\u003egb\u003c/sub\u003e), grain boundary resistance (R\u003csub\u003egb\u003c/sub\u003e), grain capacitance (C\u003csub\u003eg\u003c/sub\u003e) and grain resistance (R\u003csub\u003eg\u003c/sub\u003e). The good consistency between the fitting lines and the test results suggests that the method of adopted fitting circuit is reliable. The result show that Z\u0026prime;values of 0.88NN-0.12BF\u0026thinsp;+\u0026thinsp;1 wt% MnO\u003csub\u003e2\u003c/sub\u003e sample is much bigger than 0.88NN-0.12BF at 500\u0026deg;C. A larger Z 'value is usually associated with higher voltage resistance, suggesting that the insulation performance is improved after doping MnO\u003csub\u003e2\u003c/sub\u003e. This may be related to the large resistivity of the 0.88NN-0.12BF-Mn grains and second phase MnFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e induced local electric field.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe \u003cem\u003eE\u003c/em\u003e\u003csub\u003eb\u003c/sub\u003e value of MnO\u003csub\u003e2\u003c/sub\u003e modified 0.88NN-0.12BF ceramics is significantly associated with the uneven distribution of local electric field (LEF) causing by the formation of the second phase \u003csup\u003e[\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e, \u003cspan additionalcitationids=\"CR48\" citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e]\u003c/sup\u003e. The distribution of LEF depends on the second phase content and microstructure in ceramics. To explore the influence of MnFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e semiconductor second phase on the \u003cem\u003eE\u003c/em\u003e\u003csub\u003eb\u003c/sub\u003e of MnFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/0.88NN-0.12BF-Mn composite ceramics, according to the principle of finite element analysis, the electric field distribution inside MnFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/0.88NN-0.12BF-Mn composite ceramics was simulated using ANSYS Maxwell software under the 200 kV/cm, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003e. Circular particles represent MnFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e (\u003cem\u003eε\u003c/em\u003e\u003csub\u003er\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;5) second phase, rectangular matrix represents 0.88NN-0.12BF-Mn phase (\u003cem\u003eε\u003c/em\u003e\u003csub\u003er\u003c/sub\u003e\u0026thinsp;\u0026asymp;\u0026thinsp;600). The results indicate that due to the significant difference in \u003cem\u003eε\u003c/em\u003e\u003csub\u003er\u003c/sub\u003e, more applied voltage will be concentrated in MnFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e. On the MnFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e phase with lower \u003cem\u003eε\u003c/em\u003e\u003csub\u003er\u003c/sub\u003e, the LEF in the 0.88NN-0.12BF-Mn matrix is weakened (Fig.\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003e (a)). Therefore, the second phase of MnFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e semiconductor generated by adding MnO\u003csub\u003e2\u003c/sub\u003e can increase the \u003cem\u003eE\u003c/em\u003e\u003csub\u003eb\u003c/sub\u003e value of MnFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/0.88NN-0.12BF-Mn composite ceramics. Therefore, the redistribution of LEF induced by the second phase of MnFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e can well explain the effect of MnFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e on the breakdown of MnFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/0.88NN-0.12BF-Mn composite ceramics. These findings are consistent with the previous research of Zhang \u003cem\u003eet al\u003c/em\u003e., who successfully increased \u003cem\u003eE\u003c/em\u003e\u003csub\u003eb\u003c/sub\u003e from 132 kV/cm in pure Ba\u003csub\u003e0.4\u003c/sub\u003eSr\u003csub\u003e0.6\u003c/sub\u003eTiO\u003csub\u003e3\u003c/sub\u003e ceramics to 331 kV/cm in Ba\u003csub\u003e0.4\u003c/sub\u003eSr\u003csub\u003e0.6\u003c/sub\u003eTiO\u003csub\u003e3\u003c/sub\u003e/MgO by compounding low dielectric constant second phase MgO into Ba\u003csub\u003e0.4\u003c/sub\u003eSr\u003csub\u003e0.6\u003c/sub\u003eTiO\u003csub\u003e3\u003c/sub\u003e ceramic matrix, almost 2.5 times higher \u003csup\u003e[\u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e]\u003c/sup\u003e. Li \u003cem\u003eet al\u003c/em\u003e. used finite element software (COMSOL) to numerically simulate the distribution of electric potential and LEF, and studied the influence of the second phase on the \u003cem\u003eE\u003c/em\u003e\u003csub\u003eb\u003c/sub\u003e value of composite materials\u003csup\u003e[\u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e57\u003c/span\u003e]\u003c/sup\u003e. Based on simulations and experiments, it was found that the aggregation phenomenon caused by the excessive distribution of low dielectric constant second phases ultimately leads to more electric fields concentrated on this part of the material. The electric fields distributed on this part of the material will be much higer than the range that the material can tolerate, resulting in a decrease in the \u003cem\u003eE\u003c/em\u003e\u003csub\u003eb\u003c/sub\u003e of the composite material. Consistent findings have also been found in the 0\u0026ndash;3 type composite ceramics of Bi\u003csub\u003e0.5\u003c/sub\u003eNa\u003csub\u003e0.5\u003c/sub\u003eTiO\u003csub\u003e3\u003c/sub\u003e-SrTiO\u003csub\u003e3\u003c/sub\u003e-AgNbO\u003csub\u003e3\u003c/sub\u003e:SiO\u003csub\u003e2\u003c/sub\u003e and Bi\u003csub\u003e0.5\u003c/sub\u003eNa\u003csub\u003e0.5\u003c/sub\u003eTiO\u003csub\u003e3\u003c/sub\u003e-BaTiO\u003csub\u003e3\u003c/sub\u003e-K\u003csub\u003e0.5\u003c/sub\u003eNa\u003csub\u003e0.5\u003c/sub\u003eNbO\u003csub\u003e3\u003c/sub\u003e:ZnO \u003csup\u003e[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u003c/sup\u003e]. In addition, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003e (b), some studies have shown that the second phase of semiconductors can fix free electrons through strong electrostatic attraction, forming a local electric field and hindering the injection and transmission of charges in dielectric composite ceramics, resulting in a significant improvement in breakdown performance \u003csup\u003e[\u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e58\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"4. Conclusions","content":"\u003cp\u003eThe (1-\u003cem\u003ex\u003c/em\u003e)NN-\u003cem\u003ex\u003c/em\u003eBF lead-free solid solution ceramics were found to exhibit an obvious phase transformation from an AFE P phase to an AFE R phase with increasing BF content. The optimum energy-storage density of 7.4 J/cm\u003csup\u003e3\u003c/sup\u003e were achieved in the \u003cem\u003ex\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.12 sample with an AFE R phase structure under 500 kV/cm. In addition, it also has good frequency and temperature stability. To further improve the properties of NN\u0026minus;12BF, a small amount of MnO\u003csub\u003e2\u003c/sub\u003e was added. The obviously improved \u003cem\u003eE\u003c/em\u003e\u003csub\u003eb\u003c/sub\u003e values were achieved by doping 1 wt.% MnO\u003csub\u003e2\u003c/sub\u003e. SEM and XRD prove that 0.88NN\u0026minus;0.12BF + 1 wt.% MnO\u003csub\u003e2\u003c/sub\u003e ceramic consists of two phases, namely 0.88NN\u0026minus;0.12BF-Mn relaxor AFE and a few semiconductor MnFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e. It has been founded that a part of Mn element enters the NN-12BF main lattice and a small amount of semiconductor second phase is generated simultaneously. On the one hand, MnO\u003csub\u003e2\u003c/sub\u003e as an effective sintering aid for densification and an acceptor dopant for relaxation can improve the breakdown field strength and energy-storage efficiency of NN-12BF. On the other hand, a small amount of semiconductor second phase forms a local electric field, which can resist the transmission of charges, resulting in a greatly improvement in breakdown performance. This synergistic effect significant increases the energy-storage properties of the ceramic matrix, achieving a super high energy storage density of 13.4 J/cm\u003csup\u003e3\u003c/sup\u003e and a high energy storage efficiency of 87.4% under 700 kV/cm.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis research was supported by the Project of Henan Province Science and Technology (232102221003, 232102210183), the Special Project of Zhengzhou Basic Research and Application Basic Research (ZZSZX202435, ZZSZX202106), and the Postgraduate Education Reform and Quality Improvement Project of Henan Province \u0026nbsp; (YJS2023JD67).\u003c/p\u003e\n"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eC. Liu, F. Li, L.P. Ma, H.M. Cheng, Advanced materials for energy storage. Adv. 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Zhai, Structure-design strategy of 0\u0026ndash;3 type (Bi\u003csub\u003e0.32\u003c/sub\u003eSr\u003csub\u003e0.42\u003c/sub\u003eNa\u003csub\u003e0.20\u003c/sub\u003e)TiO\u003csub\u003e3\u003c/sub\u003e/MgO composite to boost energy storage density, efffciency and charge-discharge performance. J. Euro. Ceram. Soc. \u003cb\u003e39\u003c/b\u003e, 2889\u0026ndash;2898 (2019)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eC. Yuan, Y. Zhou, Y. Zhu, J. Liang, S. Wang, S. Peng, Y. Li, S. Cheng, M. Yang, J. Hu, B. Zhang, Polymer/molecular semiconductor all-organic composites for high-temperature dielectric energy storage. Nat. Commun. \u003cb\u003e11\u003c/b\u003e, 3919 (2020)\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":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"journal-of-electroceramics","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jecr","sideBox":"Learn more about [Journal of Electroceramics](https://link.springer.com/journal/10832)","snPcode":"10832","submissionUrl":"https://submission.nature.com/new-submission/10832/3","title":"Journal of Electroceramics","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Relaxor antiferroelectric, Composite, Energy storage, NaNbO3, Lead-free","lastPublishedDoi":"10.21203/rs.3.rs-8894516/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8894516/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eIn this reserch, (1-\u003cem\u003ex\u003c/em\u003e)NaNbO\u003csub\u003e3\u003c/sub\u003e-\u003cem\u003ex\u003c/em\u003eBiFeO\u003csub\u003e3\u003c/sub\u003e solid solutions were reported to clearly show relaxor antiferroelectric phase structure dependent energy storage properties, evolving from \u003cem\u003eW\u003c/em\u003e\u003csub\u003erec\u003c/sub\u003e = 1.63 J/cm\u003csup\u003e3\u003c/sup\u003e and \u003cem\u003eη\u0026thinsp;=\u003c/em\u003e\u0026thinsp;27% in the case of \u003cem\u003ex\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.04 at 300 kV/cm to 7.4 J/cm and 83.4% in the case of \u003cem\u003ex\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.12 at 500 kV/cm. To further decrease the dielectric loss and improve the breakdown strength of 0.88NaNbO\u003csub\u003e3\u003c/sub\u003e-0.12BiFeO\u003csub\u003e3\u003c/sub\u003e ceramic, MnO\u003csub\u003e2\u003c/sub\u003e was incorporated into it. In particular, When 1wt.% MnO\u003csub\u003e2\u003c/sub\u003e was added, a MnFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/0.88NN-0.12BF-Mn semiconductor/relaxor composite ceramic was unexpectedly obtained. A small amount of semiconductor second phase significantly increases the breakdown field strength of the material, thereby obtaining a super large energy storage density \u003cem\u003eW\u003c/em\u003e\u003csub\u003erec\u003c/sub\u003e of 13.4 J/cm\u003csup\u003e3\u003c/sup\u003e and excellent energy efficiency \u003cem\u003eη\u003c/em\u003e of 87.4% at 700 kV/cm. The finding of this study provide valuable insights of self-generated semiconductor/relaxor composite structure to obtain good energy storage performence in NaNbO\u003csub\u003e3\u003c/sub\u003e-based lead-free ceramics.\u003c/p\u003e","manuscriptTitle":"Self-generated semiconductor/relaxor antiferroelectric composite ceramics with high energy storage properties","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-02-23 09:50:57","doi":"10.21203/rs.3.rs-8894516/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-03-13T06:06:09+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-12T09:11:06+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-09T18:08:49+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-04T16:38:24+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"56300663194249436091996410248539779014","date":"2026-03-02T14:27:36+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"243322879327294110893173474369107613580","date":"2026-03-01T16:37:21+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"114220353441685331889922827797689003268","date":"2026-02-28T14:37:49+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"144274844942838613819559470846765249179","date":"2026-02-25T03:00:35+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-02-19T09:18:45+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-02-17T05:31:15+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-02-17T05:30:53+00:00","index":"","fulltext":""},{"type":"submitted","content":"Journal of Electroceramics","date":"2026-02-16T15:38:56+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"journal-of-electroceramics","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jecr","sideBox":"Learn more about [Journal of Electroceramics](https://link.springer.com/journal/10832)","snPcode":"10832","submissionUrl":"https://submission.nature.com/new-submission/10832/3","title":"Journal of Electroceramics","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"f8ebc558-a36e-4550-b04f-2c6170b32cd6","owner":[],"postedDate":"February 23rd, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-02T01:08:49+00:00","versionOfRecord":[],"versionCreatedAt":"2026-02-23 09:50:57","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8894516","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8894516","identity":"rs-8894516","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}