Structural, dielectric, ferroelectric and energy storage properties of 0.58BFO–0.3BTO–0.12NNO + x wt% CBSKN ceramics

Structural, dielectric, ferroelectric and energy storage properties of 0.58BFO–0.3BTO–0.12NNO + x wt% CBSKN ceramics | 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 Structural, dielectric, ferroelectric and energy storage properties of 0.58BFO–0.3BTO–0.12NNO + x wt% CBSKN ceramics Hui Tang, Ren-Zhi Wang, Qing-Wei Luo, Yuan-Fang Lu, Jiu-Ming Ma This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9293300/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Lead-free BiFeO 3 –BaTiO 3 (BFO–BTO) materials with giant spontaneous polarization and high Curie temperatures exhibit considerable potential for innovative applications in dielectric capacitor. However, their intrinsic drawbacks, including low electric breakdown strength and low recoverable energy storage density ( W reco ), severely limit their energy storage capabilities. In the present study, a strategy of introducing Ca/B/Si/K 0.01 /Na 0.02 (CBSKN) glass-phase liquid sintering into BFO-BTO ceramics is put forward to improve their breakdown strength and recoverable energy storage density. Ceramics with the composition 0.58BiFeO 3 –0.3BaTiO 3 –0.12NaNbO 3 + x wt% Ca/B/Si/K 0.01 /Na 0.02 were prepared using the traditional high-temperature solid-state reaction method. The incorporation of CBSKN glass powder leads to a reduction in the Δ P ( P max – P r ) value of the samples, whereas an appropriate doping content can effectively enhance the electrical breakdown strength of the ceramics. Calculations of energy storage properties show that the CBSKN05 ceramic achieves a maximum energy storage density of 2.13 J/cm 3 under an electric field of 190 kV/cm. Finally, the energy storage stability of CBSKN05 ceramics was evaluated under 100 kV/cm at various temperatures and frequencies, which indicating the incorporation of glass powder is helpful to improve thermal and frequency stability for energy storage applications. These results suggest that 0.58BFO–0.3BTO–0.12NNO ceramics modified with CBSKN glass are promising candidates for high-density energy storage devices. relaxor ferroelectric Energy-storage dielectric ceramic Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 1 Introduction Dielectric ceramic energy storage capacitors feature rapid charge–discharge speeds, high power density, and superior thermal and cycling stability, exhibiting promising applications in national defense, military engineering, power electronics, and renewable energy [ 1 – 3 ]. However, their relatively low energy storage density has become a major obstacle to practical application. Consequently, improving the energy storage performance of dielectric ceramics has emerged as a core research focus in recent years [ 3 – 6 ]. BiFeO 3 –BaTiO 3 (BFO–BTO)-based ceramics have garnered widespread attention in the field of energy storage due to their high Curie temperature ( T C ) and large spontaneous polarization ( P s ). To enhance the energy storage density of BFO–BTO dielectric ceramics, it is crucial to simultaneously increase both the polarization difference (Δ P = P max − P r ) and the breakdown electric field strength of the materials. Previous research [ 7 ] has modified BFO–BTO ceramics through A-site and B-site doping, which reduces the remnant polarization and increases Δ P , thereby promoting the energy storage density and efficiency of the BFO–BTO system. In addition, according to the energy storage density theories, increasing the dielectric breakdown field is an effective method to further improve the energy storage capacity of dielectric ceramic capacitors [ 8 – 10 ]. The breakdown electric field refers to the maximum electric field that a dielectric material can withstand, and it is one of the key performance indicators of such materials. It is closely correlated with material thickness, grain size, internal defects, bulk density, grain boundaries, band gap, dielectric constant, and other microstructural and physical factors. BiFeO 3 -based ceramics exhibit a narrow band gap. Moreover, during high-temperature sintering, bismuth volatilization, together with the variable valence and nonstoichiometry of iron, leads to high dielectric loss and large leakage conductance, thereby resulting in a low breakdown strength. Consequently, enhancing the breakdown electric field is essential to improve the energy storage density of BiFeO 3 –BaTiO 3 ceramics. Glass powder is widely adopted as a sintering aid in ceramic fabrication. Owing to its low melting point, glass softens and forms a liquid phase once the temperature reaches its glass transition or softening point during sintering. The formed liquid phase features low mass-transport resistance and rapid flow-driven diffusion. It segregates at grain boundaries during grain nucleation and growth, suppressing solid-state diffusion, lowering the sintering temperature, improving densification, and refining grain size, accordingly, introducing glass-based sintering additives can effectively boost the breakdown strength of dielectric ceramics [ 11 – 15 ]. In this work, multivalent Mn ions and NaNbO 3 are introduced into the BiFeO 3 –BaTiO 3 matrix, while Ca/B/Si/K 0.01 /Na 0.02 glass powder is incorporated as a sintering aid. The microstructure, dielectric, ferroelectric performance, energy storage characteristics, and breakdown strength of 0.58BFO–0.3BTO–0.12NNO materials are systematically investigated. 2 Experimental The 0.58BiFeO 3 –0.3BaTiO 3 –0.12NaNbO 3 + x wt% Ca/B/Si/K 0.01 /Na 0.02 ceramics (denoted as 0.58BFO–0.3BTO–0.12NNO + x wt% CBSKN, where x = 0, 0.50 and 1.00, abbreviated as CBSKN0, CBSKN05 and CBSKN10, respectively) were fabricated via a conventional high-temperature solid-state reaction method. Raw powders including Bi 2 O 3 (99%, Aladdin), Fe 2 O 3 (99%, Aladdin), BaCO 3 (99%, Aladdin), TiO 2 (99%, Aladdin), Na 2 CO 3 (99%, Aladdin), and Nb 2 O 5 (99.99%, Aladdin) were weighed according to stoichiometric ratios. Considering the high-temperature volatilization of Bi 2 O 3 , an excess of 1 wt% Bi 2 O 3 was added. The mixed powders were placed in a milling jar with yttria-stabilized zirconia balls and ethanol as the medium, followed by ball milling at 200 r/min for 24 h. After drying and sieving, the homogenized powders were calcined in a muffle furnace at 1073–1093 K for 3 h. The CBSKN glass powder was separately prepared using CaO (99%, Aladdin), H 3 BO 3 (99%, Aladdin), SiO 2 (99%, Aladdin), K 2 CO 3 (99%, Aladdin), and Na 2 CO 3 (99%, Aladdin). These precursors were melted at 1573 K for 1.5 h and then quenched in water. The prepared glass powder was added to the calcined ceramic powders at the designed mass fractions, and the mixture was subjected to ball milling again for 24 hours. After drying and sieving processes, the fine powders were granulated with 5 wt% polyvinyl butyral (PVB) binder and then uniaxially pressed into pellets. Eventually, the green compacts were sintered at a temperature range of 1233 ~ 1263 K for 4 hours. The crystal structure of the samples was characterized by X-ray diffraction (XRD, Rigaku Ultima IV). A scanning electron microscope (SEM, Hitachi S-3400N-II) was employed to observe the surface morphology. Ferroelectric hysteresis loops under various electric fields were measured using a Radiant Multiferroic system coupled with a Radiant Trek Model 609B amplifier. The temperature-dependent dielectric constant and dielectric loss were tested by a precision impedance analyzer (Agilent E4980A) within the frequency range of 1 ~ 100 kHz and temperature range of 298 ~ 773 K, with a heating rate of 2 K per minute. 3 Results and discussion Figure 1 (a) presents the XRD patterns of 0.58BFO–0.3BTO–0.12NNO + x wt% CBSKN ceramics. Based on the positions of the diffraction peaks, all samples have a typical perovskite structure as their main crystalline phase. The diffraction peaks labeled with (♦) are associated with impurity phases. The right part of Fig. 1 (a) shows the enlarged XRD patterns in the 2θ range of 38.5° to 39.5°. With the increase of CBSKN glass content, no obvious shift of the diffraction peaks is detected, which suggests that the addition of glass powder has a minimal impact on the crystal structure of the ceramics. Figure 1 (b) presents the Rietveld refinement results of the XRD data for the undoped sample ( x = 0) using GSAS+EXPGUI software, based on the Pm_3m space group [ 16 , 17]. The refined pattern matches well with the experimental data, with R wp = 0.0513, R p = 0.0371, and χ 2 = 1.248. All R factors are within reasonable ranges, confirming the high reliability of the refinement. The refined lattice parameter a is 3.992(3) Å, revealing that 0.58BFO–0.3BTO–0.12NNO ceramics possess a pseudo-cubic structure belonging to the Pm_3m space group. The theoretical density of the ceramics is 7.07 g·cm − 3 . Figures 2 (a–c) show the surface SEM micrographs of 0.58BFO–0.3BTO–0.12NNO + x wt% CBSKN ceramics. The grains exhibit a uniform granular morphology with dense packing, no obvious pores or pits, and smooth sample surfaces, indicating high densification and excellent sintering quality. The bulk densities measured by the Archimedes method are 6.82, 6.73 and 6.76 g·cm − 3 for CBSKN0, CBSKN05 and CBSKN10, respectively, with relative densities all above 95%. Grain size distributions corresponding to Figs. 2 (a–c) reveal that all samples possess fine grains. With increasing CBSKN content, the proportion of small-to-medium-sized grains increases significantly. The average grain sizes are 1.12, 0.97 and 1.04 µm for CBSKN0, CBSKN05 and CBSKN10, respectively. The low-melting-point glass fills the grain boundaries during high-temperature sintering, suppresses solid-state mass transfer, and thus refines the grain size. Figures 2 (d–i) display the elemental mapping results acquired by energy-dispersive X-ray spectroscopy (EDS). All constituent elements are distributed uniformly without noticeable local aggregation. Figure 3 illustrates the relative dielectric constant ( ε r ) and dielectric loss (tan δ ) of 0.58BFO–0.3BTO–0.12NNO + x wt% CBSKN ceramics within the temperature range of 290 ~ 630 K and frequency range of 1 kHz ~ 100 kHz. It can be observed from Fig. 3 that the dielectric temperature spectra of all 0.58BFO–0.3BTO–0.12NNO + x wt% CBSKN ceramics exhibit a distinct broad dielectric peak. As the frequency increases, the broad dielectric peak in the temperature spectrum shifts toward the high-temperature region, which is a typical feature of dielectric relaxation [ 18 , 19 ]. The peak temperature ( T m ) of CBSKN0, CBSKN05 and CBSKN10 ceramics is 573 K, implying that the introduction of CBSKN glass powder has no effect on the phase transition temperature of the ceramics. In addition, the peak values of the relative dielectric constants of CBSKN0, CBSKN05 and CBSKN10 ceramics at a frequency of 1 kHz are 2016.18, 1820.15 and 1658.02, respectively. As the content of CBSKN glass powder increases, the ε r of the ceramics decreases significantly, which is attributed to the low ε r of CBSKN glass powder itself, thereby reducing the overall ε r of the 0.58BFO–0.3BTO–0.12NNO + x wt% CBSKN ceramics. Dielectric loss (tan δ ) is one of the key parameters for evaluating the quality of ceramic samples; the smaller the tan δ , the better the quality of the ceramic. The tan δ values of CBSKN0, CBSKN05, and CBSKN10 ceramics at a frequency of 1 kHz and a temperature of 293 K are 0.0636, 0.0641, and 0.0644, respectively. The dielectric loss results indicate that CBSKN glass powder has no obvious improvement on the dielectric loss of the ceramics. Figures 4 (a–c) show the P – E hysteresis loops of 0.58BFO–0.3BTO–0.12NNO + x wt% CBSKN ceramics at room temperature under different electric fields, with a test frequency of 10 Hz. It can be observed from the figures that the P – E hysteresis loops of 0.58BFO–0.3BTO–0.12NNO + x wt% CBSKN ceramics are thin and elongated. The linearity of the hysteresis loops also indicates that the samples are relaxor ferroelectrics [ 20 , 21 ]. As mentioned earlier, BFO–BTO ceramics are conventional ferroelectrics; after the addition of NaNbO 3 components, the microstructure of the ceramics is modified, forming nano-microdomains. Thus, the 0.58BFO–0.3BTO–0.12NNO + x wt% CBSKN ceramics exhibit typical characteristics of relaxor ferroelectrics. As electric field intensity increases, the polarization intensity of 0.58BFO–0.3BTO–0.12NNO + x wt% CBSKN ceramics also increases, which is because electric domains are more prone to flipping under a strong electric field. At 160 kV/cm, the maximum polarization intensity ( P max ) and residual polarization intensity ( P r ) of CBSKN0, CBSKN05, and CBSKN10 ceramics are 26.11, 24.69, 22.91 and 1.78, 1.94, 2.52 µC/cm 2 , respectively. It is clearly shown in Fig. 4 (d) that Pmax decreases while P r increases with the increment of CBSKN glass powder content. According to the test results of this study, the solid solution of glass powder and ferroelectric material can reduce the macroscopic polarization intensity and increase the residual polarization intensity of the ferroelectric material. These results indicate that the introduction of CBSKN glass powder reduces the Δ P of the 0.58BFO–0.3BTO–0.12NNO samples. To study the energy storage characteristics of 0.58BFO–0.3BTO–0.12NNO + x wt% CBSKN ceramics, the recoverable energy storage density ( W reco ), total energy storage density ( W total , where W total = W reco + W loss ), and energy storage efficiency ( η ) were calculated based on the hysteresis loop test results. Figures 5 (a–c) show the relationships between room-temperature W reco , W total , η and electric field for 0.58BFO–0.3BTO–0.12NNO + x wt% CBSKN ceramics. As can be seen from the figures, W reco and W total of all samples increase with the enhancement of electric field. The recoverable energy storage densities ( W reco ) of CBSKN0, CBSKN05, and CBSKN10 at 160 kV/cm are 1.70, 1.64 and 1.62 J/cm 3 , respectively. In addition, the η values of CBSKN0, CBSKN05, and CBSKN10 at 160 kV/cm are 81.93%, 78.16% and 74.95%, respectively; η decreases with the increase of CBSKN glass powder content, and CBSKN05 ceramics exhibit the highest η . This is because the incorporation of CBSKN glass powder reduces the Δ P of the samples. The maximum energy storage density of CBSKN05 ceramics at 190 kV/cm is 2.13 J/cm 3 , with an energy storage efficiency of 74.76%. For conventional and relaxor ferroelectrics, since the relationship between P and E is nonlinear, W reco and E are also nonlinear, i.e., W reco ~ E n (usually n < 2) [ 22 ]. Figure 5 (d) shows the relationship between Ln( W reco ) and Ln( E ) for 0.58BFO–0.3BTO–0.12NNO + x wt% CBSKN ceramics. From the fitting results, it can be concluded that the index n of W reco ~ E n for 0.58BFO–0.3BTO–0.12NNO + x wt% CBSKN ceramics is less than 2, which is consistent with the aforementioned theory. In addition to excellent high energy storage density, dielectric ceramic capacitors also require good energy storage stability [ 23 , 24 ]. To study the energy storage stability of CBSKN05 ceramics, the hysteresis loops of CBSKN05 ceramics under different frequencies and temperatures were tested under an electric field of 100 kV/cm, and the energy storage characteristics of the ceramics were calculated, as shown in Fig. 6 . As can be seen from Figs. 6 (a–b), in the temperature range of 293 K ~ 363 K, P max and P r fluctuate around 15.5 and 1.3 µC/cm 2 , while W reco and η fluctuate around 0.65 J/cm 3 and 77%, indicating that CBSKN05 ceramics possess good energy storage temperature stability. It can be observed from Figs. 6 (c–d) that P max and W total of CBSKN05 ceramics decrease slightly with the increase of frequency. In the frequency range of 1 Hz to 100 Hz, W reco and η are stable in the ranges of 0.56 to 0.64 J/cm 3 and 73.28% to 78.87%, respectively, demonstrating that CBSKN05 ceramics have good energy storage frequency stability. 4 Conclusions The structural, dielectric, ferroelectric and energy storage properties of 0.58BFO–0.3BTO–0.12NNO + x wt% CBSKN ceramics prepared by solid-state reaction method were systematically investigated and analyzed. XRD results indicate that 0.58BFO–0.3BTO–0.12NNO + x wt% CBSKN ceramics have a pseudo-cubic structure, belonging to the Pm_3m space group. The broad peak in the dielectric temperature spectrum and the thin P – E hysteresis loops of the ceramics confirm that the samples are relaxor ferroelectrics. In addition, the addition of CBSKN glass powder reduces the Δ P of the samples, while an appropriate amount of CBSKN glass powder can enhance the breakdown field strength of the ceramics. The calculation results of energy storage characteristics show that the maximum energy storage density of CBSKN05 ceramics at 190 kV/cm is 2.13 J/cm 3 . Finally, the energy storage stability of the samples was studied by testing the P – E hysteresis loops of CBSKN05 ceramics at different temperatures and frequencies under 100 kV/cm. In the temperature range of 293 K ~ 363 K, W reco and η of CBSKN05 ceramics fluctuated around 0.65 J/cm 3 and 77%. In the frequency range of 1 Hz to 100 Hz, W reco and η of CBSKN05 ceramics are stable in the ranges of 0.56 ~ 0.64 J/cm 3 and 73.28% ~ 78.87%, respectively. These results illustrate that CBSKN05 ceramics have excellent energy storage temperature and frequency stability. It was proved that introduction of CBSKN glass-phase liquid sintering can enhance the energy storage properties of 0.58BFO–0.3BTO–0.12NNO ceramics. Declarations Author contributions All authors contributed to the study conception and design. Material preparation, data collection, analysis and original draft writing were performed by Hui Tang, Ren-Zhi Wang, Yuan-Fang Lu and Jiu-Ming Ma. The first draft of the manuscript was written by Hui Tang. Ren-Zhi Wang was responsible for supervision. Qing-Wei Luo was responsible for validation. All authors commented on previous versions of the manuscript. All authors read and approved the final manuscript. Acknowledgements This work was supported by Liuzhou Polytechnic University University-Level Research Project of the 'Double High' Professional Group in the School of Mechanical and Electrical Engineering (grant number 2025JD08); the Natural Science Foundation of Guangxi (grant number 2023GXNSFBA026287); Guangxi Young Elite Scientist Sponsorship Program (grant number GXYESS2025097); the Scientific Research Foundation for High-Level Talents of Liuzhou Vocational and Technical College (grant number 2022GCQD03); Guangxi First Batch of Young and Talented Personnel Inclusive Support Policy Scientific Research Startup Project; Middle-aged and Young Teachers' Basic Ability Promotion Project of Guangxi (grant number 2024KY1468). Data availability Data will be made available on request. Competing interests The authors declare no competing interests. References S.T. Dang, X.Q. Zhang, Y.H. Wang, Q.Z. Chai, Z.H. Peng, D. Wu, P.F. Liang, L.L. Wei, X.L. Chao, Z.P. 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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-9293300","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":620372762,"identity":"551495ff-bb53-4a08-b322-b2070ad19ea4","order_by":0,"name":"Hui Tang","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA0ElEQVRIie3OMQuCUBDA8RPhuVy53lJ9heKBCA59FSXQxYSWaIhwelPg3LcpBCd1dm/MQWiPNMQp1LaG95/ewftxByCT/WkqAM2n3XsobAlnvxJwxGiy1rL4sROmJ/QsIThYTqhl1/4tGLjWRdBWQO4SpJ4TYmAPHOYbfNIQ5WyQImInJFz2E738EI+pWJPXGEI+v9fEZqwh4RhSlIaKOa0ETjemnXhcoN9PtMjnT9yfFrqe3YrqaM0iLe0ndYzahQB2Mw79r1OrjshkMpnsW2/tXTY7ZOG7CQAAAABJRU5ErkJggg==","orcid":"","institution":"Liuzhou Polytechnic University","correspondingAuthor":true,"prefix":"","firstName":"Hui","middleName":"","lastName":"Tang","suffix":""},{"id":620372764,"identity":"c638b63f-e6ed-477f-8ff8-bd6c0631f55f","order_by":1,"name":"Ren-Zhi Wang","email":"","orcid":"","institution":"Liuzhou Polytechnic University","correspondingAuthor":false,"prefix":"","firstName":"Ren-Zhi","middleName":"","lastName":"Wang","suffix":""},{"id":620372766,"identity":"7d3a5a66-8c7b-49a4-96fe-f2b9af1fbd0f","order_by":2,"name":"Qing-Wei Luo","email":"","orcid":"","institution":"Liuzhou Polytechnic University","correspondingAuthor":false,"prefix":"","firstName":"Qing-Wei","middleName":"","lastName":"Luo","suffix":""},{"id":620372769,"identity":"3a797df0-3bf8-46f6-86be-4ca064c5202a","order_by":3,"name":"Yuan-Fang Lu","email":"","orcid":"","institution":"Liuzhou Polytechnic University","correspondingAuthor":false,"prefix":"","firstName":"Yuan-Fang","middleName":"","lastName":"Lu","suffix":""},{"id":620372771,"identity":"08ef5875-9856-4604-86ed-7bcdeb6c719c","order_by":4,"name":"Jiu-Ming Ma","email":"","orcid":"","institution":"Liuzhou Railway Vocational Technical College","correspondingAuthor":false,"prefix":"","firstName":"Jiu-Ming","middleName":"","lastName":"Ma","suffix":""}],"badges":[],"createdAt":"2026-04-01 14:38:32","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9293300/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9293300/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":107484241,"identity":"473c872b-b6b4-4805-bffe-6da2930a3e73","added_by":"auto","created_at":"2026-04-22 02:31:12","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":172612,"visible":true,"origin":"","legend":"\u003cp\u003e(a) XRD patterns of 0.58BFO–0.3BTO–0.12NNO+ \u003cem\u003ex\u003c/em\u003e wt% CBSKN ceramics; (b) Rietveld refined XRD results for BFO–BTO–0.12NNO ceramic\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-9293300/v1/a48b3a43c1f2e454e7730c02.png"},{"id":107482130,"identity":"a9562419-171c-4451-ba2a-87ac5d9f64ee","added_by":"auto","created_at":"2026-04-22 02:22:04","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1251301,"visible":true,"origin":"","legend":"\u003cp\u003eSEM pictures of 0.58BFO–0.3BTO–0.12NNO+ \u003cem\u003ex\u003c/em\u003e wt% CBSKN ceramics: (a) \u003cem\u003ex\u003c/em\u003e=0; (b) \u003cem\u003ex\u003c/em\u003e=0.5; (c) \u003cem\u003ex\u003c/em\u003e=1.0; (b) Distribution mapping of elements in 0.58BFO-0.3BTO-0.12NNO ceramics: (d) Ba; (e) Ti; (f) Bi; (g) Fe; (h) Na; (i) Nb\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-9293300/v1/cf8e068d2f03350b47311d03.png"},{"id":107482025,"identity":"a2d52832-0714-4fed-9c3c-17cc3173a656","added_by":"auto","created_at":"2026-04-22 02:21:29","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":209048,"visible":true,"origin":"","legend":"\u003cp\u003eRelative dielectric constant and dielectric loss of 0.58BFO–0.3BTO–0.12NNO+ \u003cem\u003ex\u003c/em\u003e wt% CBSKN ceramics with different and frequency: (a) \u003cem\u003ex\u003c/em\u003e=0; (b) \u003cem\u003ex\u003c/em\u003e=0.5; (c) \u003cem\u003ex\u003c/em\u003e=1.0\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-9293300/v1/f93f00547d77c20d5c43a375.png"},{"id":107226550,"identity":"192668ff-5a54-4364-a659-0ce0e65320b0","added_by":"auto","created_at":"2026-04-18 17:18:13","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":273373,"visible":true,"origin":"","legend":"\u003cp\u003eThe\u003cem\u003e P-E\u003c/em\u003e hysteresis loops at different electric field and room temperature for\u0026nbsp; 0.58BFO–0.3BTO–0.12NNO+ \u003cem\u003ex\u003c/em\u003e wt% CBSKN ceramics: (a) \u003cem\u003ex\u003c/em\u003e=0; (b) \u003cem\u003ex\u003c/em\u003e=0.5; (c) \u003cem\u003ex\u003c/em\u003e=1.0; (d) The \u003cem\u003eP\u003c/em\u003e\u003csub\u003emax\u003c/sub\u003e and \u003cem\u003eP\u003c/em\u003e\u003csub\u003er\u003c/sub\u003e as fuction of \u003cem\u003eE\u003c/em\u003e for 0.58BFO–0.3BTO–0.12NNO+ \u003cem\u003ex\u003c/em\u003e wt% CBSKN ceramics\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-9293300/v1/798da8c87f92132b3144d96f.png"},{"id":107226552,"identity":"d3201f94-f2b2-4b2a-a010-9bda7886eb93","added_by":"auto","created_at":"2026-04-18 17:18:13","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":231222,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eW\u003c/em\u003e\u003csub\u003ereco\u003c/sub\u003e, \u003cem\u003eW\u003c/em\u003e\u003csub\u003etotal\u003c/sub\u003e and \u003cem\u003eη\u003c/em\u003e as function of electric field at room temperature for\u0026nbsp; 0.58BFO–0.3BTO–0.12NNO+ \u003cem\u003ex\u003c/em\u003e wt% CBSKN: (a) \u003cem\u003ex\u003c/em\u003e=0; (b) \u003cem\u003ex\u003c/em\u003e=0.5; (c) \u003cem\u003ex\u003c/em\u003e=1.0; (d) Ln(\u003cem\u003eW\u003c/em\u003e\u003csub\u003ereco\u003c/sub\u003e) versus Ln(\u003cem\u003eE\u003c/em\u003e) for 0.58BFO–0.3BTO–0.12NNO+ \u003cem\u003ex\u003c/em\u003e wt% CBSKN ceramics\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-9293300/v1/909258c011da211a22e01677.png"},{"id":107226553,"identity":"ccafbcbc-a912-4b8d-91f6-c8cdf983b768","added_by":"auto","created_at":"2026-04-18 17:18:13","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":291722,"visible":true,"origin":"","legend":"\u003cp\u003e(a) The \u003cem\u003eP-E\u003c/em\u003e hysteresis loops at different temperature for CBSKN05 ceramics; (b) \u003cem\u003eW\u003c/em\u003e\u003csub\u003ereco\u003c/sub\u003e, \u003cem\u003eW\u003c/em\u003e\u003csub\u003etotal\u003c/sub\u003e and \u003cem\u003eη\u003c/em\u003e as function of electric field at room temperature for CBSKN05; (c) The \u003cem\u003eP\u003c/em\u003e-\u003cem\u003eE\u003c/em\u003e hysteresis loops at different frequency for CBSKN05 ceramics; (d) \u003cem\u003eW\u003c/em\u003e\u003csub\u003ereco\u003c/sub\u003e, \u003cem\u003eW\u003c/em\u003e\u003csub\u003etotal\u003c/sub\u003e and \u003cem\u003eη\u003c/em\u003e as function of electric field at different frequency for CBSKN05\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-9293300/v1/80c140746519d4013f78e381.png"},{"id":107487058,"identity":"6211f065-6f83-4118-b26f-ae79892208a3","added_by":"auto","created_at":"2026-04-22 02:39:45","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2348681,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9293300/v1/00e4c1c3-7fde-41c3-aa01-a1bb03a6fd1b.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003e\u003cstrong\u003eStructural, dielectric, ferroelectric and energy storage properties of 0.58BFO–0.3BTO–0.12NNO + \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003ex\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e wt% CBSKN ceramics\u003c/strong\u003e\u003c/p\u003e","fulltext":[{"header":"1 Introduction","content":"\u003cp\u003eDielectric ceramic energy storage capacitors feature rapid charge\u0026ndash;discharge speeds, high power density, and superior thermal and cycling stability, exhibiting promising applications in national defense, military engineering, power electronics, and renewable energy [\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. However, their relatively low energy storage density has become a major obstacle to practical application. Consequently, improving the energy storage performance of dielectric ceramics has emerged as a core research focus in recent years [\u003cspan additionalcitationids=\"CR4 CR5\" citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. BiFeO\u003csub\u003e3\u003c/sub\u003e\u0026ndash;BaTiO\u003csub\u003e3\u003c/sub\u003e (BFO\u0026ndash;BTO)-based ceramics have garnered widespread attention in the field of energy storage due to their high Curie temperature (\u003cem\u003eT\u003c/em\u003e\u003csub\u003eC\u003c/sub\u003e) and large spontaneous polarization (\u003cem\u003eP\u003c/em\u003e\u003csub\u003es\u003c/sub\u003e). To enhance the energy storage density of BFO\u0026ndash;BTO dielectric ceramics, it is crucial to simultaneously increase both the polarization difference (Δ\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;\u003cem\u003eP\u003c/em\u003e\u003csub\u003emax\u003c/sub\u003e \u0026minus; \u003cem\u003eP\u003c/em\u003e\u003csub\u003er\u003c/sub\u003e) and the breakdown electric field strength of the materials. Previous research [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] has modified BFO\u0026ndash;BTO ceramics through A-site and B-site doping, which reduces the remnant polarization and increases Δ\u003cem\u003eP\u003c/em\u003e, thereby promoting the energy storage density and efficiency of the BFO\u0026ndash;BTO system. In addition, according to the energy storage density theories, increasing the dielectric breakdown field is an effective method to further improve the energy storage capacity of dielectric ceramic capacitors [\u003cspan additionalcitationids=\"CR9\" citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. The breakdown electric field refers to the maximum electric field that a dielectric material can withstand, and it is one of the key performance indicators of such materials. It is closely correlated with material thickness, grain size, internal defects, bulk density, grain boundaries, band gap, dielectric constant, and other microstructural and physical factors. BiFeO\u003csub\u003e3\u003c/sub\u003e-based ceramics exhibit a narrow band gap. Moreover, during high-temperature sintering, bismuth volatilization, together with the variable valence and nonstoichiometry of iron, leads to high dielectric loss and large leakage conductance, thereby resulting in a low breakdown strength. Consequently, enhancing the breakdown electric field is essential to improve the energy storage density of BiFeO\u003csub\u003e3\u003c/sub\u003e\u0026ndash;BaTiO\u003csub\u003e3\u003c/sub\u003e ceramics. Glass powder is widely adopted as a sintering aid in ceramic fabrication. Owing to its low melting point, glass softens and forms a liquid phase once the temperature reaches its glass transition or softening point during sintering. The formed liquid phase features low mass-transport resistance and rapid flow-driven diffusion. It segregates at grain boundaries during grain nucleation and growth, suppressing solid-state diffusion, lowering the sintering temperature, improving densification, and refining grain size, accordingly, introducing glass-based sintering additives can effectively boost the breakdown strength of dielectric ceramics [\u003cspan additionalcitationids=\"CR12 CR13 CR14\" citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn this work, multivalent Mn ions and NaNbO\u003csub\u003e3\u003c/sub\u003e are introduced into the BiFeO\u003csub\u003e3\u003c/sub\u003e\u0026ndash;BaTiO\u003csub\u003e3\u003c/sub\u003e matrix, while Ca/B/Si/K\u003csub\u003e0.01\u003c/sub\u003e/Na\u003csub\u003e0.02\u003c/sub\u003e glass powder is incorporated as a sintering aid. The microstructure, dielectric, ferroelectric performance, energy storage characteristics, and breakdown strength of 0.58BFO\u0026ndash;0.3BTO\u0026ndash;0.12NNO materials are systematically investigated.\u003c/p\u003e"},{"header":"2 Experimental","content":"\u003cp\u003eThe 0.58BiFeO\u003csub\u003e3\u003c/sub\u003e\u0026ndash;0.3BaTiO\u003csub\u003e3\u003c/sub\u003e\u0026ndash;0.12NaNbO\u003csub\u003e3\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;\u003cem\u003ex\u003c/em\u003e wt% Ca/B/Si/K\u003csub\u003e0.01\u003c/sub\u003e/Na\u003csub\u003e0.02\u003c/sub\u003e ceramics (denoted as 0.58BFO\u0026ndash;0.3BTO\u0026ndash;0.12NNO\u0026thinsp;+\u0026thinsp;\u003cem\u003ex\u003c/em\u003e wt% CBSKN, where \u003cem\u003ex\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0, 0.50 and 1.00, abbreviated as CBSKN0, CBSKN05 and CBSKN10, respectively) were fabricated via a conventional high-temperature solid-state reaction method. Raw powders including Bi\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e (99%, Aladdin), Fe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e (99%, Aladdin), BaCO\u003csub\u003e3\u003c/sub\u003e (99%, Aladdin), TiO\u003csub\u003e2\u003c/sub\u003e (99%, Aladdin), Na\u003csub\u003e2\u003c/sub\u003eCO\u003csub\u003e3\u003c/sub\u003e (99%, Aladdin), and Nb\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003e (99.99%, Aladdin) were weighed according to stoichiometric ratios. Considering the high-temperature volatilization of Bi\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, an excess of 1 wt% Bi\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e was added. The mixed powders were placed in a milling jar with yttria-stabilized zirconia balls and ethanol as the medium, followed by ball milling at 200 r/min for 24 h. After drying and sieving, the homogenized powders were calcined in a muffle furnace at 1073\u0026ndash;1093 K for 3 h. The CBSKN glass powder was separately prepared using CaO (99%, Aladdin), H\u003csub\u003e3\u003c/sub\u003eBO\u003csub\u003e3\u003c/sub\u003e (99%, Aladdin), SiO\u003csub\u003e2\u003c/sub\u003e (99%, Aladdin), K\u003csub\u003e2\u003c/sub\u003eCO\u003csub\u003e3\u003c/sub\u003e (99%, Aladdin), and Na\u003csub\u003e2\u003c/sub\u003eCO\u003csub\u003e3\u003c/sub\u003e (99%, Aladdin). These precursors were melted at 1573 K for 1.5 h and then quenched in water. The prepared glass powder was added to the calcined ceramic powders at the designed mass fractions, and the mixture was subjected to ball milling again for 24 hours. After drying and sieving processes, the fine powders were granulated with 5 wt% polyvinyl butyral (PVB) binder and then uniaxially pressed into pellets. Eventually, the green compacts were sintered at a temperature range of 1233\u0026thinsp;~\u0026thinsp;1263 K for 4 hours.\u003c/p\u003e \u003cp\u003eThe crystal structure of the samples was characterized by X-ray diffraction (XRD, Rigaku Ultima IV). A scanning electron microscope (SEM, Hitachi S-3400N-II) was employed to observe the surface morphology. Ferroelectric hysteresis loops under various electric fields were measured using a Radiant Multiferroic system coupled with a Radiant Trek Model 609B amplifier. The temperature-dependent dielectric constant and dielectric loss were tested by a precision impedance analyzer (Agilent E4980A) within the frequency range of 1\u0026thinsp;~\u0026thinsp;100 kHz and temperature range of 298\u0026thinsp;~\u0026thinsp;773 K, with a heating rate of 2 K per minute.\u003c/p\u003e"},{"header":"3 Results and discussion","content":"\u003cp\u003eFigure \u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e1\u003c/span\u003e (a) presents the XRD patterns of 0.58BFO\u0026ndash;0.3BTO\u0026ndash;0.12NNO\u0026thinsp;+\u0026thinsp;\u003cem\u003ex\u003c/em\u003e wt% CBSKN ceramics. Based on the positions of the diffraction peaks, all samples have a typical perovskite structure as their main crystalline phase. The diffraction peaks labeled with (\u0026diams;) are associated with impurity phases. The right part of Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e1\u003c/span\u003e (a) shows the enlarged XRD patterns in the 2θ range of 38.5\u0026deg; to 39.5\u0026deg;. With the increase of CBSKN glass content, no obvious shift of the diffraction peaks is detected, which suggests that the addition of glass powder has a minimal impact on the crystal structure of the ceramics.\u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e1\u003c/span\u003e (b) presents the Rietveld refinement results of the XRD data for the undoped sample (\u003cem\u003ex\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0) using GSAS+EXPGUI software, based on the \u003cem\u003ePm_3m\u003c/em\u003e space group [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, 17]. The refined pattern matches well with the experimental data, with \u003cem\u003eR\u003c/em\u003e\u003csub\u003ewp\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;0.0513, \u003cem\u003eR\u003c/em\u003e\u003csub\u003ep\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;0.0371, and χ\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;1.248. All \u003cem\u003eR\u003c/em\u003e factors are within reasonable ranges, confirming the high reliability of the refinement. The refined lattice parameter a is 3.992(3) \u0026Aring;, revealing that 0.58BFO\u0026ndash;0.3BTO\u0026ndash;0.12NNO ceramics possess a pseudo-cubic structure belonging to the \u003cem\u003ePm_3m\u003c/em\u003e space group. The theoretical density of the ceramics is 7.07 g\u0026middot;cm\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eFigures \u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e2\u003c/span\u003e (a\u0026ndash;c) show the surface SEM micrographs of 0.58BFO\u0026ndash;0.3BTO\u0026ndash;0.12NNO\u0026thinsp;+\u0026thinsp;\u003cem\u003ex\u003c/em\u003e wt% CBSKN ceramics. The grains exhibit a uniform granular morphology with dense packing, no obvious pores or pits, and smooth sample surfaces, indicating high densification and excellent sintering quality. The bulk densities measured by the Archimedes method are 6.82, 6.73 and 6.76 g\u0026middot;cm\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e for CBSKN0, CBSKN05 and CBSKN10, respectively, with relative densities all above 95%.\u003c/p\u003e \u003cp\u003eGrain size distributions corresponding to Figs.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e2\u003c/span\u003e (a\u0026ndash;c) reveal that all samples possess fine grains. With increasing CBSKN content, the proportion of small-to-medium-sized grains increases significantly. The average grain sizes are 1.12, 0.97 and 1.04 \u0026micro;m for CBSKN0, CBSKN05 and CBSKN10, respectively. The low-melting-point glass fills the grain boundaries during high-temperature sintering, suppresses solid-state mass transfer, and thus refines the grain size. Figures\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e2\u003c/span\u003e (d\u0026ndash;i) display the elemental mapping results acquired by energy-dispersive X-ray spectroscopy (EDS). All constituent elements are distributed uniformly without noticeable local aggregation.\u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e3\u003c/span\u003e illustrates the relative dielectric constant (\u003cem\u003eε\u003c/em\u003e\u003csub\u003er\u003c/sub\u003e) and dielectric loss (tan\u003cem\u003eδ\u003c/em\u003e) of 0.58BFO\u0026ndash;0.3BTO\u0026ndash;0.12NNO\u0026thinsp;+\u0026thinsp;\u003cem\u003ex\u003c/em\u003e wt% CBSKN ceramics within the temperature range of 290\u0026thinsp;~\u0026thinsp;630 K and frequency range of 1 kHz\u0026thinsp;~\u0026thinsp;100 kHz. It can be observed from Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e3\u003c/span\u003e that the dielectric temperature spectra of all 0.58BFO\u0026ndash;0.3BTO\u0026ndash;0.12NNO\u0026thinsp;+\u0026thinsp;\u003cem\u003ex\u003c/em\u003e wt% CBSKN ceramics exhibit a distinct broad dielectric peak. As the frequency increases, the broad dielectric peak in the temperature spectrum shifts toward the high-temperature region, which is a typical feature of dielectric relaxation [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. The peak temperature (\u003cem\u003eT\u003c/em\u003e\u003csub\u003em\u003c/sub\u003e) of CBSKN0, CBSKN05 and CBSKN10 ceramics is 573 K, implying that the introduction of CBSKN glass powder has no effect on the phase transition temperature of the ceramics. In addition, the peak values of the relative dielectric constants of CBSKN0, CBSKN05 and CBSKN10 ceramics at a frequency of 1 kHz are 2016.18, 1820.15 and 1658.02, respectively. As the content of CBSKN glass powder increases, the \u003cem\u003eε\u003c/em\u003e\u003csub\u003er\u003c/sub\u003e of the ceramics decreases significantly, which is attributed to the low \u003cem\u003eε\u003c/em\u003e\u003csub\u003er\u003c/sub\u003e of CBSKN glass powder itself, thereby reducing the overall \u003cem\u003eε\u003c/em\u003e\u003csub\u003er\u003c/sub\u003e of the 0.58BFO\u0026ndash;0.3BTO\u0026ndash;0.12NNO\u0026thinsp;+\u0026thinsp;\u003cem\u003ex\u003c/em\u003e wt% CBSKN ceramics. Dielectric loss (tan\u003cem\u003eδ\u003c/em\u003e) is one of the key parameters for evaluating the quality of ceramic samples; the smaller the tan\u003cem\u003eδ\u003c/em\u003e, the better the quality of the ceramic. The tan\u003cem\u003eδ\u003c/em\u003e values of CBSKN0, CBSKN05, and CBSKN10 ceramics at a frequency of 1 kHz and a temperature of 293 K are 0.0636, 0.0641, and 0.0644, respectively. The dielectric loss results indicate that CBSKN glass powder has no obvious improvement on the dielectric loss of the ceramics.\u003c/p\u003e \u003cp\u003eFigures \u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e4\u003c/span\u003e (a\u0026ndash;c) show the \u003cem\u003eP\u003c/em\u003e\u0026ndash;\u003cem\u003eE\u003c/em\u003e hysteresis loops of 0.58BFO\u0026ndash;0.3BTO\u0026ndash;0.12NNO\u0026thinsp;+\u0026thinsp;\u003cem\u003ex\u003c/em\u003e wt% CBSKN ceramics at room temperature under different electric fields, with a test frequency of 10 Hz. It can be observed from the figures that the \u003cem\u003eP\u003c/em\u003e\u0026ndash;\u003cem\u003eE\u003c/em\u003e hysteresis loops of 0.58BFO\u0026ndash;0.3BTO\u0026ndash;0.12NNO\u0026thinsp;+\u0026thinsp;\u003cem\u003ex\u003c/em\u003e wt% CBSKN ceramics are thin and elongated. The linearity of the hysteresis loops also indicates that the samples are relaxor ferroelectrics [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. As mentioned earlier, BFO\u0026ndash;BTO ceramics are conventional ferroelectrics; after the addition of NaNbO\u003csub\u003e3\u003c/sub\u003e components, the microstructure of the ceramics is modified, forming nano-microdomains. Thus, the 0.58BFO\u0026ndash;0.3BTO\u0026ndash;0.12NNO\u0026thinsp;+\u0026thinsp;\u003cem\u003ex\u003c/em\u003e wt% CBSKN ceramics exhibit typical characteristics of relaxor ferroelectrics. As electric field intensity increases, the polarization intensity of 0.58BFO\u0026ndash;0.3BTO\u0026ndash;0.12NNO\u0026thinsp;+\u0026thinsp;\u003cem\u003ex\u003c/em\u003e wt% CBSKN ceramics also increases, which is because electric domains are more prone to flipping under a strong electric field. At 160 kV/cm, the maximum polarization intensity (\u003cem\u003eP\u003c/em\u003e\u003csub\u003emax\u003c/sub\u003e) and residual polarization intensity (\u003cem\u003eP\u003c/em\u003e\u003csub\u003er\u003c/sub\u003e) of CBSKN0, CBSKN05, and CBSKN10 ceramics are 26.11, 24.69, 22.91 and 1.78, 1.94, 2.52 \u0026micro;C/cm\u003csup\u003e2\u003c/sup\u003e, respectively. It is clearly shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e4\u003c/span\u003e(d) that Pmax decreases while \u003cem\u003eP\u003c/em\u003e\u003csub\u003er\u003c/sub\u003e increases with the increment of CBSKN glass powder content. According to the test results of this study, the solid solution of glass powder and ferroelectric material can reduce the macroscopic polarization intensity and increase the residual polarization intensity of the ferroelectric material. These results indicate that the introduction of CBSKN glass powder reduces the Δ\u003cem\u003eP\u003c/em\u003e of the 0.58BFO\u0026ndash;0.3BTO\u0026ndash;0.12NNO samples.\u003c/p\u003e \u003cp\u003eTo study the energy storage characteristics of 0.58BFO\u0026ndash;0.3BTO\u0026ndash;0.12NNO\u0026thinsp;+\u0026thinsp;\u003cem\u003ex\u003c/em\u003e wt% CBSKN ceramics, the recoverable energy storage density (\u003cem\u003eW\u003c/em\u003e\u003csub\u003ereco\u003c/sub\u003e), total energy storage density (\u003cem\u003eW\u003c/em\u003e\u003csub\u003etotal\u003c/sub\u003e, where \u003cem\u003eW\u003c/em\u003e\u003csub\u003etotal\u003c/sub\u003e = \u003cem\u003eW\u003c/em\u003e\u003csub\u003ereco\u003c/sub\u003e + \u003cem\u003eW\u003c/em\u003e\u003csub\u003eloss\u003c/sub\u003e), and energy storage efficiency (\u003cem\u003eη\u003c/em\u003e) were calculated based on the hysteresis loop test results. Figures\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e5\u003c/span\u003e (a\u0026ndash;c) show the relationships between room-temperature \u003cem\u003eW\u003c/em\u003e\u003csub\u003ereco\u003c/sub\u003e, \u003cem\u003eW\u003c/em\u003e\u003csub\u003etotal\u003c/sub\u003e, \u003cem\u003eη\u003c/em\u003e and electric field for 0.58BFO\u0026ndash;0.3BTO\u0026ndash;0.12NNO\u0026thinsp;+\u0026thinsp;\u003cem\u003ex\u003c/em\u003e wt% CBSKN ceramics. As can be seen from the figures, \u003cem\u003eW\u003c/em\u003e\u003csub\u003ereco\u003c/sub\u003e and \u003cem\u003eW\u003c/em\u003e\u003csub\u003etotal\u003c/sub\u003e of all samples increase with the enhancement of electric field. The recoverable energy storage densities (\u003cem\u003eW\u003c/em\u003e\u003csub\u003ereco\u003c/sub\u003e) of CBSKN0, CBSKN05, and CBSKN10 at 160 kV/cm are 1.70, 1.64 and 1.62 J/cm\u003csup\u003e3\u003c/sup\u003e, respectively. In addition, the \u003cem\u003eη\u003c/em\u003e values of CBSKN0, CBSKN05, and CBSKN10 at 160 kV/cm are 81.93%, 78.16% and 74.95%, respectively; \u003cem\u003eη\u003c/em\u003e decreases with the increase of CBSKN glass powder content, and CBSKN05 ceramics exhibit the highest \u003cem\u003eη\u003c/em\u003e. This is because the incorporation of CBSKN glass powder reduces the Δ\u003cem\u003eP\u003c/em\u003e of the samples. The maximum energy storage density of CBSKN05 ceramics at 190 kV/cm is 2.13 J/cm\u003csup\u003e3\u003c/sup\u003e, with an energy storage efficiency of 74.76%.\u003c/p\u003e \u003cp\u003eFor conventional and relaxor ferroelectrics, since the relationship between \u003cem\u003eP\u003c/em\u003e and \u003cem\u003eE\u003c/em\u003e is nonlinear, \u003cem\u003eW\u003c/em\u003e\u003csub\u003ereco\u003c/sub\u003e and \u003cem\u003eE\u003c/em\u003e are also nonlinear, i.e., \u003cem\u003eW\u003c/em\u003e\u003csub\u003ereco\u003c/sub\u003e ~ \u003cem\u003eE\u003c/em\u003e\u003csub\u003en\u003c/sub\u003e (usually n\u0026thinsp;\u0026lt;\u0026thinsp;2) [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Figure\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e5\u003c/span\u003e (d) shows the relationship between Ln(\u003cem\u003eW\u003c/em\u003e\u003csub\u003ereco\u003c/sub\u003e) and Ln(\u003cem\u003eE\u003c/em\u003e) for 0.58BFO\u0026ndash;0.3BTO\u0026ndash;0.12NNO\u0026thinsp;+\u0026thinsp;\u003cem\u003ex\u003c/em\u003e wt% CBSKN ceramics. From the fitting results, it can be concluded that the index n of \u003cem\u003eW\u003c/em\u003e\u003csub\u003ereco\u003c/sub\u003e ~ \u003cem\u003eE\u003c/em\u003e\u003csub\u003en\u003c/sub\u003e for 0.58BFO\u0026ndash;0.3BTO\u0026ndash;0.12NNO\u0026thinsp;+\u0026thinsp;\u003cem\u003ex\u003c/em\u003e wt% CBSKN ceramics is less than 2, which is consistent with the aforementioned theory.\u003c/p\u003e \u003cp\u003eIn addition to excellent high energy storage density, dielectric ceramic capacitors also require good energy storage stability [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. To study the energy storage stability of CBSKN05 ceramics, the hysteresis loops of CBSKN05 ceramics under different frequencies and temperatures were tested under an electric field of 100 kV/cm, and the energy storage characteristics of the ceramics were calculated, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e. As can be seen from Figs.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e (a\u0026ndash;b), in the temperature range of 293 K\u0026thinsp;~\u0026thinsp;363 K, \u003cem\u003eP\u003c/em\u003e\u003csub\u003emax\u003c/sub\u003e and \u003cem\u003eP\u003c/em\u003e\u003csub\u003er\u003c/sub\u003e fluctuate around 15.5 and 1.3 \u0026micro;C/cm\u003csup\u003e2\u003c/sup\u003e, while \u003cem\u003eW\u003c/em\u003e\u003csub\u003ereco\u003c/sub\u003e and \u003cem\u003eη\u003c/em\u003e fluctuate around 0.65 J/cm\u003csup\u003e3\u003c/sup\u003e and 77%, indicating that CBSKN05 ceramics possess good energy storage temperature stability. It can be observed from Figs.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e (c\u0026ndash;d) that \u003cem\u003eP\u003c/em\u003e\u003csub\u003emax\u003c/sub\u003e and \u003cem\u003eW\u003c/em\u003e\u003csub\u003etotal\u003c/sub\u003e of CBSKN05 ceramics decrease slightly with the increase of frequency. In the frequency range of 1 Hz to 100 Hz, \u003cem\u003eW\u003c/em\u003e\u003csub\u003ereco\u003c/sub\u003e and \u003cem\u003eη\u003c/em\u003e are stable in the ranges of 0.56 to 0.64 J/cm\u003csup\u003e3\u003c/sup\u003e and 73.28% to 78.87%, respectively, demonstrating that CBSKN05 ceramics have good energy storage frequency stability.\u003c/p\u003e"},{"header":"4 Conclusions","content":"\u003cp\u003eThe structural, dielectric, ferroelectric and energy storage properties of 0.58BFO\u0026ndash;0.3BTO\u0026ndash;0.12NNO\u0026thinsp;+\u0026thinsp;\u003cem\u003ex\u003c/em\u003e wt% CBSKN ceramics prepared by solid-state reaction method were systematically investigated and analyzed. XRD results indicate that 0.58BFO\u0026ndash;0.3BTO\u0026ndash;0.12NNO\u0026thinsp;+\u0026thinsp;\u003cem\u003ex\u003c/em\u003e wt% CBSKN ceramics have a pseudo-cubic structure, belonging to the \u003cem\u003ePm_3m\u003c/em\u003e space group. The broad peak in the dielectric temperature spectrum and the thin \u003cem\u003eP\u003c/em\u003e\u0026ndash;\u003cem\u003eE\u003c/em\u003e hysteresis loops of the ceramics confirm that the samples are relaxor ferroelectrics. In addition, the addition of CBSKN glass powder reduces the Δ\u003cem\u003eP\u003c/em\u003e of the samples, while an appropriate amount of CBSKN glass powder can enhance the breakdown field strength of the ceramics. The calculation results of energy storage characteristics show that the maximum energy storage density of CBSKN05 ceramics at 190 kV/cm is 2.13 J/cm\u003csup\u003e3\u003c/sup\u003e. Finally, the energy storage stability of the samples was studied by testing the \u003cem\u003eP\u003c/em\u003e\u0026ndash;\u003cem\u003eE\u003c/em\u003e hysteresis loops of CBSKN05 ceramics at different temperatures and frequencies under 100 kV/cm. In the temperature range of 293 K\u0026thinsp;~\u0026thinsp;363 K, \u003cem\u003eW\u003c/em\u003e\u003csub\u003ereco\u003c/sub\u003e and \u003cem\u003eη\u003c/em\u003e of CBSKN05 ceramics fluctuated around 0.65 J/cm\u003csup\u003e3\u003c/sup\u003e and 77%. In the frequency range of 1 Hz to 100 Hz, \u003cem\u003eW\u003c/em\u003e\u003csub\u003ereco\u003c/sub\u003e and \u003cem\u003eη\u003c/em\u003e of CBSKN05 ceramics are stable in the ranges of 0.56\u0026thinsp;~\u0026thinsp;0.64 J/cm\u003csup\u003e3\u003c/sup\u003e and 73.28% ~ 78.87%, respectively. These results illustrate that CBSKN05 ceramics have excellent energy storage temperature and frequency stability. It was proved that introduction of CBSKN glass-phase liquid sintering can enhance the energy storage properties of 0.58BFO\u0026ndash;0.3BTO\u0026ndash;0.12NNO ceramics.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAuthor contributions\u0026emsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll authors contributed to the study conception and design. Material preparation, data collection, analysis and original draft writing were performed by Hui Tang, Ren-Zhi Wang, Yuan-Fang Lu and Jiu-Ming Ma. The first draft of the manuscript was written by Hui Tang. Ren-Zhi Wang was responsible for supervision. Qing-Wei Luo was responsible for validation. All authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by Liuzhou Polytechnic University University-Level Research Project of the \u0026apos;Double High\u0026apos; Professional Group in the School of Mechanical and Electrical Engineering (grant number 2025JD08); the Natural Science Foundation of Guangxi (grant number 2023GXNSFBA026287); Guangxi Young Elite Scientist Sponsorship Program (grant number GXYESS2025097); the Scientific Research Foundation for High-Level Talents of Liuzhou Vocational and Technical College (grant number 2022GCQD03); Guangxi First Batch of Young and Talented Personnel Inclusive Support Policy Scientific Research Startup Project; Middle-aged and Young Teachers\u0026apos; Basic Ability Promotion Project of Guangxi (grant number 2024KY1468).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u0026ensp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eData will be made available on request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u0026emsp;The authors declare no competing interests.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eS.T. 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Reaney, Lead-free (Ba,Sr)TiO\u003csub\u003e3\u003c/sub\u003e-BiFeO\u003csub\u003e3\u003c/sub\u003e based multilayer ceramic capacitors with high energy density. J. Eur. Ceram. Soc. \u003cstrong\u003e40,\u003c/strong\u003e 1779\u0026ndash;1783 (2020).\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"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":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"relaxor ferroelectric, Energy-storage, dielectric ceramic","lastPublishedDoi":"10.21203/rs.3.rs-9293300/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9293300/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eLead-free BiFeO\u003csub\u003e3\u003c/sub\u003e\u0026ndash;BaTiO\u003csub\u003e3\u003c/sub\u003e (BFO\u0026ndash;BTO) materials with giant spontaneous polarization and high Curie temperatures exhibit considerable potential for innovative applications in dielectric capacitor. However, their intrinsic drawbacks, including low electric breakdown strength and low recoverable energy storage density (\u003cem\u003eW\u003c/em\u003e\u003csub\u003ereco\u003c/sub\u003e), severely limit their energy storage capabilities. In the present study, a strategy of introducing Ca/B/Si/K\u003csub\u003e0.01\u003c/sub\u003e/Na\u003csub\u003e0.02\u003c/sub\u003e (CBSKN) glass-phase liquid sintering into BFO-BTO ceramics is put forward to improve their breakdown strength and recoverable energy storage density. Ceramics with the composition 0.58BiFeO\u003csub\u003e3\u003c/sub\u003e\u0026ndash;0.3BaTiO\u003csub\u003e3\u003c/sub\u003e\u0026ndash;0.12NaNbO\u003csub\u003e3\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;\u003cem\u003ex\u003c/em\u003e wt% Ca/B/Si/K\u003csub\u003e0.01\u003c/sub\u003e/Na\u003csub\u003e0.02\u003c/sub\u003e were prepared using the traditional high-temperature solid-state reaction method. The incorporation of CBSKN glass powder leads to a reduction in the Δ\u003cem\u003eP\u003c/em\u003e (\u003cem\u003eP\u003c/em\u003e\u003csub\u003emax\u003c/sub\u003e\u0026ndash;\u003cem\u003eP\u003c/em\u003e\u003csub\u003er\u003c/sub\u003e) value of the samples, whereas an appropriate doping content can effectively enhance the electrical breakdown strength of the ceramics. Calculations of energy storage properties show that the CBSKN05 ceramic achieves a maximum energy storage density of 2.13 J/cm\u003csup\u003e3\u003c/sup\u003e under an electric field of 190 kV/cm. Finally, the energy storage stability of CBSKN05 ceramics was evaluated under 100 kV/cm at various temperatures and frequencies, which indicating the incorporation of glass powder is helpful to improve thermal and frequency stability for energy storage applications. These results suggest that 0.58BFO\u0026ndash;0.3BTO\u0026ndash;0.12NNO ceramics modified with CBSKN glass are promising candidates for high-density energy storage devices.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e","manuscriptTitle":"Structural, dielectric, ferroelectric and energy storage properties of 0.58BFO–0.3BTO–0.12NNO + x wt% CBSKN ceramics","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-18 17:18:09","doi":"10.21203/rs.3.rs-9293300/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"fb471dc2-d994-4b7a-8073-a54aada12d57","owner":[],"postedDate":"April 18th, 2026","published":true,"recentEditorialEvents":[{"type":"decision","content":"Revision requested","date":"2026-05-02T00:47:02+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-01T05:38:12+00:00","index":24,"fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-05-12T06:44:26+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-18 17:18:09","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9293300","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9293300","identity":"rs-9293300","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}