The BaO-Al2O3-CaO-SiO2 (BACS) based glass-ceramic composites have been prepared by firing mixtures of BACS glasses and Al2O3 ceramic filler. The addition of CaO can regulate both the crystallization behavior and densification process of the composite. X-ray diffraction (XRD) analysis revealed that BaAl2Si2O8 was the main crystallized phase during sintering. Excess CaO in glass can induce the formation of Ca2Al2SiO7 phases, which deteriorate the dielectric properties. Scanning electron microscopy demonstrated the coexistence of BaAl2Si2O8 and Al2O3 phases in the sintered bodies. The coexistence was further confirmed by the XRD results. The LTCC green tape based on the BACS-40 wt% Al2O3 composites was obtained through the tape-casting process. The tapes with 4 wt% CaO content in BACS glass revealed good compatibility between the ceramic and silver, without defects such as warping and blistering being observed. The BACS3-40 wt% Al2O3 composites based green tapes sintered at 850 degrees C for 30 min exhibited the: epsilon(r) value similar to 7.8, tan delta similar to 0.003 at 20-50 GHz. The desirable and relatively stable dielectric properties over a wide frequency range make it a promising candidate material for RF module and electronic packaging substrates.

Achieving high mechanical quality factor (Qm) and large piezoelectric coefficient (d33) concurrently is critical for high-power piezoelectric ceramics but remains challenging due to their inherent trade-off. In this study, a synergistic strategy combining phase-boundary and defect engineering via manganese doped tetragonal (T)-rich morphotropic phase boundary (MPB) composition based on a modified Pb(Mg1/3Nb2/3)O3-Pb(Zr,Ti)O3 (PMN-PZT) system is employed. In this modified PMN-PZT system, ultrahigh d33 of 641 pC/N was achieved in the T-rich MPB compositions. Subsequent incorporation of low-valence Mn ions can form the defect dipoles that strongly interact with the spontaneous polarization of T phase, leading to the suppression of the domain wall motion. This induces drastic enhancement of Qm, while maintaining the relatively large d33. Consequently, the optimal electrical properties of Qm = 890, d33 = 460 pC/N, kp = 0.56, tan δ = 0.57

In spite of high Curie temperature (Tc), the application of BiFeO3-PbTiO3 (BF-PT) based ceramics as hightemperature piezoelectric devices remains challenging due to their relatively low piezoelectric coefficient (d33). Herein, hierarchical domain-engineered BF-PT based ceramics with enhanced piezoelectricity across a broad temperature range are developed. By introducing (Ba0.90Ca0.10)(Sn0.15Ti0.85)O3 into the BF-PT matrix ((0.78-x)BF-0.22PT-x(Ba0.90Ca0.10)(Sn0.15Ti0.85)O3), a hierarchical domain structure exhibiting microdomain stripes interspersed with nanodomains is formed near the rhombohedral-tetragonal morphotropic phase boundary (MPB) while maintaining relatively large lattice distortion. This induces that the optimized composition (x = 0.20) exhibits a high d33 of 360 pC/N and a high Tc of 418 degrees C. Remarkably, owing to the robust phase structure and domain structure at the elevated temperatures, the fluctuation of ex-situ d33 is less than +/- 15 % over a broad temperature range of 27-380 degrees C, and meanwhile, in-situ d33 exhibits excellent piezoelectric performances at 25-400 degrees C, outperforming most reported perovskite piezoceramics. This work demonstrates that engineering hierarchical domains in BF-PT based ceramics can effectively balance high piezoelectricity and Tc, offering a promising route for designing high-performance BF-PT based high-temperature piezoelectric ceramics.

Despite the widespread research of relaxor ferroelectrics in pulsed power capacitors, achieving both high recoverable energy density (W rec) and efficiency (eta) under moderate electric field range is still challenged because domain miniaturization required to enhance eta generally leads to the delayed polarization saturation and the reduced spontaneous polarization. Here, highly polarizable clusters of superparaelectrics with locally coexisted multiphase are demonstrated by introducing Bi0.5Li0.5ZrO3 into the BaTiO3 matrix. The synergistic introduction of additional A-site polarization contribution, the miniaturization of domains into polar clusters, and the local multiphase coexistence enable both the high maximal polarization (P max) at the moderate electric field and the extremely low polarization hysteresis. As a result, the combined effects of heterogeneous cations with A-site driven ferroelectricity, A-site valence state difference, and A- and B-sites ionic radius difference lead to both giant W rec of approximate to 9.11 J cm-3 and high eta of approximate to 95.3% concurrently under a moderate electric field of 47 kV mm-1. This work demonstrates that modulating the polarization characteristic of relaxor ferroelectric ceramics can achieve low electric field driven superior energy-storage performances.

The development of high-performance BiFeO3-PbTiO3 (BF-PT) piezoelectric compositions is highly desirable, but still challenged due to their high Curie temperature (T-c), large lattice distortion and octahedral tilt induced large antiferrodistortion in rhombohedral-tetragonal phase (R3c-P4 mm) coexisted compositions. Here, a dual strategy by introducing the pseudo-cubic (Pc) phase in place of the R3c phase, and adjusting the lattice distortion of P4 mm phase was realized in 0.60Bi(0.95)La(0.05)FeO(3)-(0.40-x)PbTiO3-xBaTiO(3), where a large piezoelectric coefficient d(33) of similar to 410 pC/N, a high T-c of similar to 416 degrees C as well as a good thermal stability can be achieved at x = 0.20 composition. The structural analyses indicate that the superior piezoelectric activity should be associated with several factors including the coexistence of tetragonal (T) and Pc phases without octahedral tilt, the field-induced reversible T-Pc transition and the optimized c/a ratio. More pronouncedly, the extrinsic piezoelectric response induced by significantly enhanced domain wall motion contributes to almost similar to 70 % of the quasi-static d(33) value. Moreover, the robust domain texture up to similar to 400 degrees C is responsible for its good thermal stability. These merits suggest giant potentials of the elaborately-designed composition as high-temperature piezoelectric materials.

High activation energy of Li+ transport caused by space charge layer in ceramic-polymer composite electrolytes results in low ion conductivity. Introducing dielectric materials is a promising approach to mitigate this issue. Here, we propose a three-dimensional coupling network for constructing a robust Li transporting pathway by fabricating a BaTiO3-Li0.3La0.567TiO3 dielectric skeleton membrane using ultrafast high-temperature sintering and tape casting. The dielectric skeleton is mechanically strong even with a thickness of similar to 30 mu m. Meanwhile, due to the short sintering time of similar to 3 s, the grain sizes of the dielectric skeleton are constrained to similar to 180 nm, increasing the polymer filling volume to achieve the "percolation point" in composite materials. The 3D dielectric coupling effects help to mitigate the space charge and acquire a homogeneous Li+ distribution across the interface, decreasing the activation energy of Li(+)transporting from 0.34 eV to 0.29 eV. After polarized at an electric field, the ion conductivity of the dielectric composite electrolytes improves from 0.19 mScm(-1) to 0.24 mScm(-1). The symmetric cell using the polarized dielectric electrolytes exhibits excellent cycling stability for similar to 430 h at 0.2 mAcm(-2), similar to 130 h at 0.4 mAcm(-2), and similar to 70 h at 1 mAcm(-2). The full cell LiFePO4/polarized dielectric electrolytes/Li exhibits high-rate performance of nearly 1C (1C=170 mAg(-1)) and long-term cycling stability (>300 cycles at 50 mAg(-1)). Pairing with high-voltage cathode LiNi0.8Co0.1Mn0.1O2, the battery can cycle stably for similar to 100 cycles at 20 mAg(-1), with a Coulombic efficiency of 98 %. These results open a new avenue for the application of composite electrolytes in energy-storage devices.

Development of piezoelectric materials through chemical design meets the requirement of the next-generation electronic devices, yet the sensitive piezoelectricity to both chemical components and operational environment call for the trial and error method during material preparation. In order to give an atomic-level understanding about functional unit and assist the chemical design, deep learning was applied to train a novel model based on the most popular BaTiO3 system, as a case study in this work. Through training the atomic force field of calcium and stannum doped solid-solution with Deep Potential method, 3D structure of chemical distribution and corresponding polarization configuration can be constructed for different compositions under different temperatures, which exhibits a high degree of consistency with the local structure quantitatively analyzed from HAADF STEM and reverse Monte Carlo refinement of neutron total scattering data, especially for the critical composition with ultrahigh piezoelectricity of d33 ~ 860 pC/N. Systemic analysis reveals that variations in chemical bond length among various elements with oxygen elements are the primary factors influencing ferroelectric activity and leading to structural evolution. The results and methodology can facilitate the discovery of new ferroelectrics and the design of high-performance piezo/ferroelectrics with atomic-level insights.

Owing to the ferroelectric-ferroelectric phase transition and macrodomains switching during the polarization process, it is challenging to achieve both large strain with low hysteresis in ferroelectric ceramics, which severely limits their usefulness for practical applications. In this work, an effective strategy of constructing multiple local polarization configurations is designed in lead-free (100-x)Na0.52K0.48Nb0.9Sb0.1O3-xBaZrO3 (NKNS-xBZ) ceramics. The incorporation of BZ regulates both the polymorphic phase transition temperature and relaxor behavior of the NKNS matrix, leading to the coexistence of nanoscaled rhombohedral, orthorhombic, and tetragonal phases with ergodic relaxor at room temperature. Consequently, these polar nanodomains with multiple symmetries significantly decrease the polarization and strain hysteresis, leading to the high electrostrictive-like strain (~0.2%) and extremely low strain hysteresis (~7.4%) with good thermal stability (strain decrease < 10% from 20oC to 160oC) at x = 4. This work provides effective guidance for obtaining high strain with low hysteresis in relaxor ferroelectrics.

Relaxor ferroelectrics have garnered enormous attention for their great application potential in pulsed power energy-storage capacitors, while simultaneously achieving large recoverable energy density (Wrec) and high efficiency (η) remains a formidable challenge. Through collaboratively controlling multiscale structure via a combination of composition design and processing improvement, polar nanodomains with multiple local symmetries were engineered in ultrafine grains, enabling significantly reduced polarization hysteresis, delayed saturation polarization, maintained high polarization, and enhanced breakdown strength. As a result, an excellent comprehensive energy-storage performance of Wrec ~11.8J/cm3 and η ~88.7% is achieved in the (Na, K)NbO3-based spark-plasma-sintered lead-free ceramics, together with stable charge-discharge properties of power density ~176.3MW/cm3, discharge energy density ~3.2J/cm3, and discharge time ~43ns over a wide temperature range of 20-140oC. The studied ceramic demonstrates great advantages in advanced capacitive energy-storage applications.

Relaxor ferroelectrics are highly desired for pulse-power dielectric capacitors, however it has become a bottleneck that substantial enhancements of energy density generally sacrifice energy efficiency under superhigh fields. Here, we demonstrate a novel concept of highly polarizable concentrated dipole glass in delicately-designed high-entropy (Bi1/3Ba1/3Na1/3)(Fe2/9Ti5/9Nb2/9)O3 ceramic achieved via substitution of multiple heterovalent ferroelectric-active principal cation species on equivalent lattice sites. The atomic-scaled polar heterogeneity of dipoles with different polar vectors between adjacent unit cells enables diffuse reorientation process but disables appreciable growth with electric fields. These unique features cause superior recoverable energy density of ~15.9 J cm−3 and efficiency of ~93.3% in bulk ceramics. We also extend the highly polarizable concentrated dipole glass to the prototype multilayer ceramic capacitor, which exhibits record-breaking recoverable energy density of ~26.3 J cm−3 and efficiency of ~92.4% with excellent temperature and cycle stability. This research presents a distinctive approach for designing high-performance energy-storage dielectric capacitors. The authors introduce the concept of highly polarizable concentrated dipole glass, involving the reduction of polar order scale from the nanoscaled polar nanodomains in traditional relaxor ferroelectrics to atomic-scale individual dipoles.

Ferroelectric ceramics possessing excellent piezoelectricity and high-temperature stability simultaneously are significant for sensor and actuation applications in severe environment such as extraterrestrial exploration and petroleum extraction. Herein, a novel (0.735− x )(Bi 0.972 La 0.028 )FeO 3 –0.265PbTiO 3 – x Ba(Zr 0.2 Ti 0.8 )O 3 (abbreviated as (0.735− x )BLF–0.265PT– x BZT) was reported to own excellent piezoelectric coefficient d 33 value of ~ 394 pC/N with good temperature stability and high Curie temperature T C value of ~ 445 °C, simultaneously, at x = 0.14, which is just located at the tetragonal (T)-rich side of rhombohedral (R)-T morphotropic phase boundary (MPB). It reveals that the compositions undergo an obvious phase from R phase to T phase via an R–T MPB, and finally to the coexistence of T and pseudo-cubic (PC) phases, which is found to be accompanied by the normal-relaxor ferroelectric transformation. The significant enhancement of the piezoelectric activity in x = 0.14 sample can be attributed to synergistic effect of R–T MPB and the normal-relaxor ferroelectric transformation, leading to the significantly enhanced domain switching although the sample exhibits a relatively large T distortion of ~ 1.039. In addition, the large tetragonality of T phase allows the sample to maintain high T C value. The present work provides a guideline for the subsequent design of BF–PT-based high-temperature piezoelectric ceramics.

Bismuth sodium titanate (BNT)-based lead-free ceramics have attracted a great deal of attention due to their large electrostrains. In this work, a remarkably symmetric strain of 0.7% together with excellent temperature (0.5-0.7% from 25 to 100 degrees C)/frequency (Delta S<4% from 1 to 20 Hz) stability was observed in the 0.91(Bi0.5Na0.5) TiO3-0.06BaTiO3-0.03NaNbO3 (BNT-6BT-3NN) AFE P4bm ceramic through constructing R3c/P4mm/P4bm triple-phase coexistence phase boundary. Compared with other two compositions near double-phase coexistence ferroelectric (FE)-antiferroelectric (AFE) phase boundaries, the BNT-6BT-3NN ceramic exhibits a unique field-induced multiple phase transition from the initial AFE P4bm phase to the metastable FE P4mm phase and finally into the FE R3c phase. In-situ structural analysis evidenced a significantly enhanced lattice strain but a comparable strain value from domain switching in BNT-6BT-3NN compared with other compositions. The present study provides a novel strategy for designing high-performance large-strain ceramics in BNT-based relaxor AFE systems.

Forming morphotropic phase boundary (MPB) is crucial to improve the piezoelectric properties of lead-free NaNbO3-BaTiO3-xABO3 (NN-BT-xABO3) ceramics. In this work, four NN-BT-xABO3 systems (ABO3 = K0.5Bi0.5TiO3 (KBT), Bi0.5Na0.5TiO3 (BNT), K0.5Bi0.5ZrO3 (KBZ), and Bi0.5Na0.5ZrO3 (BNZ)) were constructed to analyze the relationship between ABO3 characteristic and phase transformation behavior. The results showed that the NN-BT-xKBT/xBNT systems underwent ferroelectric tetragonal (T)-relaxor ferroelectric T phase transformation with d33 ∼ 150 pC/N and kp ∼ 0.2 in NN-BT-0.11KBT and NN-BT-0.09BNT compositions, while the NN-BT-xKBZ/xBNZ systems underwent ferroelectric T- ferroelectric rhombohedral (R) morphotropic phase transformation with improved d33 ∼ 256 pC/N and kp ∼ 0.31 in NN-BT-0.04BNZ composition. The B-site ion radius was found to be a key factor in inducing phase transformation. The incorporation of small Ti4+ ions tends to break the long ordering of ferroelectrics, inducing the normal-relaxor ferroelectric phase transformation, however, the appearance of the R phase in NN-BT-xAZrO3 compositions was attributed to the chemical pressure caused by buckled Zr-O-Zr bonds as larger Zr4+ ions enter the NN-BT matrix lattices. This study will deepen the understanding of the ferroelectric phase transformation mechanism in the lead-free NaNbO3 material system and provide a guidance for designing morphotropic NN-based lead-free piezoelectric ceramics.

Although BiFeO3-BaTiO3-based lead-free ceramics have attracted much attention in recent years as a high temperature piezoelectrics, their d(33) value is still difficult to exceed 200 pC/N through conventional methods. In this work, a novel (0.7-x)BiFeO3-0.3BaTiO(3)-xLa(Mg2/3Nb1/3)O-3 (x = 0-0.005) ternary system was reported to own excellent room-temperature piezoelectric constant (d(33)) similar to 216 pC/N and high Curie temperature (480 degrees C) at x = 0.003 simultaneously. It reveals that the compositions undergo an obvious phase transition from ferroelectric (FE) rhombohedral (R) phase to relaxor pseudo-cubic (PC) phase via an R-PC morphotropic phase boundary (MPB). More importantly, piezoelectric nonlinear Rayleigh analysis and S-E/P-E curves suggest that the signif-icantly enhanced domain dynamics due to the coexistence of macrodomain and nanodomain can be observed in the x = 0.003 sample. The synergy of these two effects induce the improved d(33) value observed in the x = 0.003 sample. In addition, the compositions exhibit the inhibition of defect dipoles and the improvement of the high temperature resistivity, leading to the excellent thermal stability with sensitivity coefficients eta less than +/- 5% in the annealing temperature range of 25-400 degrees C. The present work provides a guideline for the subsequent design of high-temperature lead-free ceramics.

Simultaneously enhanced d 33 and T c values were realized in BF–BT-based lead-free MPB piezoceramics through cooperatively regulating the lattice distortion and content of rhombohedral phase, domain heterogeneity and defect concentration.

Achieving large piezoelectric response and high Curie temperature, simultaneously, are of great demand but have been rarely achieved in BiFeO3-PbTiO3 (BF-PT) based morphotropic phase boundary (MPB) systems. In this work, in-situ synchrotron x-ray diffraction and transmission electron microscopy were carried out in BF-PT-0.19Ba(Zr,Ti)O3 high-temperature piezoceramic, a recently reported MPB composition with high piezoelectric coefficient, to elucidate the underlying structural mechanism. A field induced irreversible transition from tetragonal (T) P4mm phase to rhombohedral (R) R3c phase is identified although R and T phases are still coexisted after poling. This induces the significantly enhanced irreversible domain switching of both R and T phases and the reversible domain switching of R phase but only a slightly enhanced reversible switching of T phase of as compared with other BF-PT-x Ba(Zr,Ti)O3 MPB compositions, leading to the significant increase of lattice strain up to ∼0.15% but only a slightly increase of strain from extrinsic domain switching due to the strong coupling between lattice strain and domain switching in both R and T phases, although the strain contribution seems to be composition independent after the field induced irreversible phase transition. The present study demonstrates a new performance enhancement mechanism to design the high-performance BF-PT based high-temperature piezoelectric ceramics in terms of the different roles of R and T phases within MPB.

Pratical applications have put forward great challenges to the comprehensive energy-storage performance of ceramic material. Here, a novel route of simultaneously manipulating multiscale structure and the field-induced structural transformation in (Bi0.5Na0.5)TiO3-based ceramics is proposed to address the above concern. The multiscale structure of 0.88(Bi0.5Na0.5)TiO3-0.12BaTiO3 solid solutions such as grain and domain size, band gap, and phase structure can be adjusted by adding antiferroelectric NaNbO3. Simultaneously, a field-induced P4bm relaxor antiferroelectric to P4mm ferroelectric phase transformation can be obtained by constructing a P4mm-P4bm phase boundary, which is expected to require a lower energy barrier compared with the field-induced P4bm relaxor antiferroelectric to R3c ferroelectric transformation in other (Bi0.5Na0.5)TiO3-based ceramics. The optimized field-induced structural transformation behavior and the formation of nanodomains enables a minimized polarization hysteresis but an enhanced maximum polarization. Moreover, the decreased grain size together with increased band gap leads to a significantly improved breakdown strength. Accordingly, a giant energy density Wrec ∼ 8.0 J/cm3, a high efficiency η ∼ 86%, a short discharging time t0.9 ∼ 41 ns, and a good temperature stability (Wrec = 1.32 ± 0.12 J/cm3, η = 88.5% ± 2.5% @ 25-200 °C) are simultaneously obtained in 0.63(Bi0.5Na0.5)TiO3-0.12BaTiO3-0.25NaNbO3 relaxor antiferroelectric ceramics, demonstrating large potentials for the ceramic capacitor applications.

Achieving high overall energy-storage properties under moderate electric fields is of great significance for practical applications of energy-storage ceramic capacitors. In this work, an ultrahigh recoverable energy-storage density (Wrec) of - 3.9 J/cm3 and a high energy-storage efficiency (eta) of - 80% are simultaneously achieved under a moderate electric field of 25 kV/mm in a new ternary lead-free relaxor ferroelectric (FE) ceramic of 1 wt. %Nb2O5-doped 0.46Bi1.02FeO3-0.29BaTiO3-0.25Bi0.5Na0.5TiO3 (BF-BT-BNT). Together with excellent thermal and frequency stability of Wrec = 1.68 +/- 12% J/cm3, eta = 90 +/- 9%, 0.1-100 Hz; Wrec = 1.61 +/- 6% J/cm3, eta = 87 +/- 5% within 30-170 degrees C, a large power density of PD - 43.0 MW/cm3 and a fast discharge rate of t0.9 - 45 ns, Nb2O5-doped BF-BT-BNT ceramics exhibit promising potentials for environment-friendly advanced pulsed power capacitors. Multiscale structure characterization reveals that the incorporation of Nb2O5 into BF-BT-BNT significantly increases the local structure disorder, leading to a heterogeneous nanodomain morphology. This makes the Nb2O5-doped BF-BT-BNT ceramic maintain a high maximum polarization, but obviously suppressed polarization hysteresis, thus responsible for significantly improved overall energy-storage properties.

Dielectric ceramics with outstanding energy-storage performances are nowadays in great demand for pulsed power electronic systems. Here, we propose a synergistic design strategy to significantly enhance the energy-storage properties of (1 - x)(0.94Na0.5Bi0.5TiO3-0.06BaTiO3)-xCaTi0.75Ta0.2O3 solid solution ceramics through introducing polar nanoregions, shifting rhombohedral to tetragonal phase transition below room temperature (stable antiferroelectric characteristic), as well as increasing the band gap in the system. Ultrahigh energy-storage properties with a record value of recoverable energy-storage density Wrec ∼ 9.55 J/cm3 and a high efficiency η ∼ 88% are achieved in Na0.5Bi0.5TiO3-based bulk ceramics with x = 0.24. Moreover, high Wrec (>3.4 J/cm3) and η (>90%) with a variation of less than 6% can be observed in a wide frequency and temperature frequency range of 5-200 Hz and 25-140 °C. Our research result not only indicates the great possibility of Na0.5Bi0.5TiO3-based lead-free compositions to replace lead-based energy-storage ceramics but also gives an effective strategy to design ultrahigh energy-storage performances for eco-friendly ceramics.