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In many studies, the properties of BiFeO3–BaTiO3 (BF–BT) ceramics vary greatly using different raw reagents, which makes it challenging to obtain reliable and repeatable properties of BF–BT‐based devices. In this work, 0.7BiFeO3–0.3BaTiO3 (0.7BF–0.3BT) ceramics were fabricated by a conventional solid‐phase synthesis using TiO2 reagents with varied purities of 98%, 99%, 99.9%, and 99.99%, respectively. The phase structure, microstructure, ferroelectric, and piezoelectric properties were comprehensively studied. All compositions of the ceramics exhibit a pseudo‐cubic phase perovskite structure, and the fraction of the rhombohedral phase increases with increasing the TiO2 purity. Additionally, backscattered electron images and energy‐dispersive spectroscopy revealed an obvious core–shell structure within grains. In particular, the 0.7BF–0.3BT ceramics prepared with 98% purity TiO2 exhibited superior ferroelectric and piezoelectric properties, d33 ∼ 220 pC/N and d33∗$d_{{\mathrm{33}}}^{\;*}$ ∼ 230 pm/V. The ceramics prepared with higher purity TiO2 suffered from severe leakage conduction, which can be well addressed by adding excess TiO2. Our work reveals the importance of different grades of purity TiO2 on the electrical properties of BF–BT ceramics. [ABSTRACT FROM AUTHOR]

Dielectric ceramics with both excellent energy storage and optical transmittance have attracted much attention in recent years. However, the transparent Pb‐free energy‐storage ceramics were rare reported. In this work, we prepared transparent relaxor ferroelectric ceramics (1 − x)Bi0.5Na0.5TiO3–xNaNbO3 (BNT–xNN) by conventional solid‐state reaction method. We find the NN‐doping can enhance the polarization and breakdown strength of BNT by suppressing the grain growth and restrained the reduction of Ti4+ to Ti3+. As a result, a high recoverable energy‐storage density of 5.14 J/cm3 and its energy efficiency of 79.65% are achieved in BNT–0.5NN ceramic at 286 kV/cm. Furthermore, NN‐doping can promote the densification to improve the optical transmittance of BNT, rising from ∼26% (x = 0.2) to ∼32% (x = 0.5) in the visible light region. These characteristics demonstrate the potential application of BNT–xNN as transparent energy‐storage dielectric ceramics. [ABSTRACT FROM AUTHOR]

Piezoelectric and ferroelectric ceramics with a high Curie temperature (Tc) have attracted much attention owing to their applications in severe environments. In this work, phase structure and dielectric, ferroelectric, and piezoelectric properties of (0.975 − x)BiScO3-xPbTiO3-0.025Pb(Cd1/3Nb2/3)O3 (BS-xPT-PCN) ceramics (x = 0.58–0.64) were studied. A composition-induced structural transformation occurs from the rhombohedral to tetragonal phase through an intermediate monoclinic phase with the increasing PT concentration. The relationship between the structure and electrical properties of the system was discussed. The BS-xPT-PCN system near the morphotropic phase boundary (MPB) (x = 0.62) exhibits excellent piezoelectric and ferroelectric performances with d33 = 508 pC/N, kp = 56%, and Pr = 40 μC/cm2. The high-temperature piezoelectricity of the sample with MPB (x = 0.62) was characterized by an in situ XRD. The excellent thermal stability of the crystal structure and the piezoelectric property indicate that the BS-xPT-PCN system is a promising candidate for high-temperature piezoelectric applications. [ABSTRACT FROM AUTHOR]

Dielectric energy-storage ceramics have the advantages of high power density and fast charge and discharge rates, and are considered to be excellent candidate materials for pulsed power-storage capacitors. At present, the application of dielectric energy-storage ceramics is hindered by their low energy density and the fact that most of them contain elemental lead. Therefore, lead-free dielectric energy-storage ceramics with high energy storage density have become a research hot spot. In this paper, we first present the requirements that dielectric energy-storage capacitors impose on the properties of ceramic materials. We then review our previous research work combined with research progress into bismuth (Bi)-based lead-free energy-storage ceramics including Bi0.5Na0.5TiO3 (BNT), BiFeO3, and Bi0.2Sr0.7TiO3, in which the composition design ideas and related energy-storage characteristics of BNT-based lead-free energy-storage ceramics are emphasized. At the same time, we highlight the problems faced by Bi-based lead-free energy-storage ceramics and some strategies for addressing them. Finally, we examine the future prospects of research into Bi-based lead-free energy-storage ceramics. [ABSTRACT FROM AUTHOR]

Recently, AgNbO3 antiferroelectric ceramics have attracted great attention by virtue of their characters of high energy storage density and environmental friendliness. To further optimize the electrical properties, in this work, Lu2O3 modified AgNbO3 ceramics were prepared via conventional solid state method. Crystal structure and element analysis indicated the Lu3+ ion preferred to enter the A-site when Lu2O3 content was lower than 2 mol%, otherwise, it was more likely to form LuNbO4 or Lu3NbO7-based solid solutions. Remarkably improved stability of antiferroelectric phase was observed once Lu3+ ions enter into the A-site, on account of the decrease of cell volume and tolerance factor. As a consequence, an enhanced recoverable energy storage density (Wrec) of 3.5 J/cm3 was achieved in 1 mol% Lu2O3 modified AgNbO3 ceramics at 210 kV/cm, which is superior to the other lead-free ceramics under moderate electric field (< 220 kV/cm). It is believed our study will provide a good reference for the development of AgNbO3-based dielectric capacitors. [ABSTRACT FROM AUTHOR]

Environmentally benign lead‐free bulk ceramics with high recoverable energy density (Wrec) are very attractive in advanced pulsed power capacitors. In this work, composition engineering was adopted by La3+ modification to improve the energy storage performance of Ag1−3xLaxNbO3 ceramics. It was found that the antiferroelectric (AFE) phase was stabilized after La3+ substitution, as a result of the reduced tolerance factor t. Significant improvement of Wrec and energy storage efficiency (η) were achieved with value of 3.12 J/cm3 and 0.63 for x = 0.02 at an electric field of 230 kV/cm, more than 1.5 times the value of pure AgNbO3 (Wrec = 1.9 J/cm3, η = 0.40). The excellent energy storage properties are resulted from the increased antiferroelectric‐ferroelectric phase transition electric field (EF), ferroelectric‐antiferroelectric phase transition electric field (EA), and breakdown electric field (Eb). The enhanced Eb was ascribed to the decreased grain size and increased electrical resistivity upon La3+ modification. The feature makes Ag1−3xLaxNbO3 a potential candidate for energy storage applications. [ABSTRACT FROM AUTHOR]

Phase diagram of the solid solution system K 0.5 Na 0.5 NbO 3 - Bi ½ Na ½ TiO 3 [(1-x)KNN-xBNT] has been established from dielectric permittivity measurement and structure analyses. The unit cell volumes continuously decrease depending on the composition, while the local structure maintains distortions away from the cubic average structure in the range 0.10 ≤ x ≤ 0.90. No clear correspondence for the temperatures of phase transition exists between structural studies and physical properties. The dielectric behavior is depicted successively from normal ferroelectric, diffuse phase transition, re-entrant-like relaxor, relaxor + dipolar glass-like relaxor, BNT-like relaxor with the increase of BNT. A comprehensive composition-property phase diagram for this system has been given to understand the various ferroelectric phenomena. The result could be mainly elucidated by the nanoclusters and the disorder driven nucleation of polar nanoregions contributed by a valence mismatch at one of the cation sites. [ABSTRACT FROM AUTHOR]

The piezoelectric properties of (K0.5Na0.5)NbO3 (KNN) are normally enhanced by chemical substitutions or doping to form solid solutions. In this study, we report that the piezoelectric properties of KNN and thermal stability of piezoelectric coefficient d33 can be both enhanced by forming the composite of KNN:ZnO. The d33 of KNN:0.2ZnO can be improved to 110 pC/N by introducing the ZnO nanoparticles, which is better than the pure KNN (d33 = 85 pC/N). The Curie temperature (TC = 407°C) remains well comparable to the pure KNN (TC = 408°C). Furthermore, the thermal stability of both remanent polarization (Pr) and piezoelectric parameter (d33) is improved. The enhanced thermal stability could be related to the induced built-in electric field or the enhanced sinterability by the addition of ZnO. The present results may help to optimize the piezoelectric properties of lead-free materials by forming composite. [ABSTRACT FROM AUTHOR]

Crystal structure, piezoelectric, and dielectric properties were investigated in the new lead-free BKT-based piezoelectric ceramics of (1− x)( Bi1/2 K1/2) TiO3- x Bi( Mg2/3 Nb1/3) O3. The morphotropic phase boundary (MPB) of the system between tetragonal and rhombohedral phases lies near the composition of x = 0.02. The optimal piezoelectric property of small-signal d33 is much enhanced to be 96 pC/N ( x = 0.01), which is higher than any other BKT-based compositions. By the introduction of Bi( Mg2/3 Nb1/3) O3, the ceramics exhibit a lower coercive field EC. In addition, a relaxor-like behavior with a frequency-dependent Curie temperature Tm is observed, and high Curie temperature Tm around 380°C is obtained in the investigated system. This study suggests that the piezoelectric properties of BKT can be significantly improved by the means of Bi( Mg2/3 Nb1/3) O3 substitution. [ABSTRACT FROM AUTHOR]

LiF was selected as a sintering additive to improve the sinterability of the 0.996(0.95K0.5Na0.5NbO3-0.05LiSbO3)-0.004BiFeO3lead-free piezoelectric ceramics. Results suggested that at room temperature the phase structure of the studied ceramics shifted from the coexistence of two phases to a phase in which orthorhombic was dominant when the LiF value was higher than 1.5 mol%, meanwhile, a pronounced shift of the Curie point to higher temperature was observed. The sample with 2 mol% LiF exhibited a higher mechanical quality factor Qmvalue of ∼75.18. With increasing temperature from 30 to 120°C, the remnant polarization of the sample increased monotonically. [ABSTRACT FROM PUBLISHER]

Na 1/2 Bi 1/2 TiO 3 (NBT)-based materials are promising lead-free alternatives due to their large electrostrain and stable mechanical quality factor. Nonetheless, the relatively low depolarization temperature (T d) impairs its practical application. Recently, quenching from sintering temperature was adopted to increase T d of NBT-based ceramics. However, the origin of the quenching-induced increase in T d is still debated. In this study, quenching effects in (1-x)(0.4Na 1/2 Bi 1/2 TiO 3 -0.6BiFeO 3)-xBaTiO 3 ceramics are investigated. With increasing BaTiO 3 content, this system transforms from ferroelectric to relaxor state at room temperature, with a criticality at x = 0.07, which exhibits R 3 c and P 4 bm coexisted phases. Ferroelectric and relaxor compositions exhibit different responses upon quenching. Upon quenching the ferroelectrics, T d increases from 420 to 580 °C for x = 0.04, but d 33 is majorly unaltered. However, upon quenching the relaxors, T d increases marginally, while d 33 increases from 62 to 97 pC/N. The correlation between the structural evolution and electrical responses upon quenching ferroelectric and relaxor compositions is explored. [ABSTRACT FROM AUTHOR]

• Evidently enhanced AFE stability is achieved in all lanthanide ions doped ReAN samples compared to pristine AgNbO 3. • Lanthanide ions can enter either A- or B-site, leading to a complex change of AFE stability and tolerance factor. • Wrec and η are achieved to be respective around 4.5 J/cm3 and 65 % for compositions from SmAN to TbAN under 250 kV/cm. • This study provides a comprehensive knowledge of lanthanide element dopants in AgNbO 3 system. The aliovalent A-site modification in Silver niobate (AgNbO 3 , AN) antiferroelectrics has exhibited its advances in improving energy storage performance, but lack of a comprehensive understanding. In this work, 3 mol% lanthanide elements (Re: Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm) modified AgNbO 3 (ReAN) ceramics were investigated. Compared with pristine AN, the ReAN ceramics exhibited decreased M1-M2 phase transition temperature and typical double-like P - E loops. The antiferroelectricity improved firstly from SmAN to TbAN because of reduction of tolerance factor, then it decayed with increasing atomic number due to partial Re3+ ions entering into B-site. Consequently, high recoverable energy density (W rec ≈ 4.5 J/cm3) and efficiency (η ≈ 65 %) were achieved for the compositions from SmAN to TbAN under 250 kV/cm. While a general decrease in W rec and η was observed by further increasing atomic number. This study provides a comprehensive knowledge of lanthanide element dopants in AgNbO 3 system. [ABSTRACT FROM AUTHOR]

• The novel piezoelectric ceramics of 0.36BiScO 3 -0.64PbTiO 3 -1 wt% Sb 2 O 5 - x wt% Nb 2 O 5 were prepared by solid-state reaction approach. • The sample with x = 1.0 demonstrates the optimal properties, including a giant d 33 of 498 pC/N (10.7 % higher than pure BS-PT ceramics), a high t c of 392 °C, a high depolarization temperature of 362 °C and a large remanent polarization of 52.7 μC/cm2 (55.9 % higher than pure BS-PT ceramics). • The enhanced ferroelectric and piezoelectric properties are attributed to a relaxation behavior originated from the formation of polar nanoregions and reduced concentration of oxygen vacancy. Here, novel ferroelectric ceramics of Sb/Nb co-doped 0.36BiScO 3 -0.64PbTiO 3 (BS-PT-Sb 2 O 5 - x Nb 2 O 5) of complex perovskite structure are reported with compositions near the morphotropic phase boundary (MPB) where the dominant monoclinic and tetragonal phases coexist. Excitingly, the incorporation of Sb/Nb dopants leads to a remarkable enhancement in both ferroelectric and piezoelectric properties. Notably, the sample with x = 1.0 demonstrates the optimal properties, boasting a giant piezoelectric coefficient (d 33) of 498 pC/N (10.7 % higher than pure BS-PT ceramics), a high Curie temperature (T c) of 392 °C, a high depolarization temperature of 362 °C and a large remanent polarization of 52.7 μC/cm2 (55.9 % higher than pure BS-PT ceramics). The enhanced ferroelectric and piezoelectric properties are ascribed to a relaxation behavior originating from the formation of polar nanoregions (PNRs) and reduced concentration of oxygen vacancy. The result provides an opportunity to elucidate the relationship between relaxation behavior and electrical properties, offering prospects for substantially improving the performance of piezoelectric ceramics. [Display omitted] [ABSTRACT FROM AUTHOR]

With co-substitution of (Li 0.5 Sm 0.5) at A site and W at B site, the electrical properties of modified Ca 0.92 (Li 0.5 Sm 0.5) 0.08 Bi 2 Nb 2- x W x O 9 [(CLS)BN- x W, x = 0, 0.015 and 0.03] piezoceramics with ultrahigh Curie temperature (T C) of > 930 °C were enhanced dramatically. The increased resistivity induced by the co-substitution ensure them to be polarized under an enough high field. Combined with the increase of spontaneous ferroelectric polarization (P S), the significant enhancements in the piezoelectric, dielectric and ferroelectric properties can be obtained in the composition x = 0.015. Furthermore, the piezoelectric activity (d 33) and bulk resistivity (ρ b) of (CLS)BN-0.015 W can be further enhanced at an appropriate sintering temperature. This optimum composition sintered at 1170 °C shows ultrahigh T C of ∼948 °C, d 33 of ∼17.3 pC/N and ρ b of ∼6.9 MΩ cm at 600 °C, which are comparable to those of the reported high-temperature Aurivillius piezoceramics with T C > 850 °C. [ABSTRACT FROM AUTHOR]

Two novel microwave dielectric materials LiBO 2 (B = Ga, In) were synthesized by a solid-state reaction method. The orthorhombic structured LiGaO 2 sintered at 1075 °C for 4 h exhibits a relative density of 96.1 ± 0.2 % and dielectric properties, namely, ε r ∼ 5.82 ± 0.01 (16.7 ± 0.1 GHz), Q × f = 24,500 ± 2000 GHz, and τ f ∼ -74.3 ± 2 ppm/°C. Meanwhile, the tetragonal structured LiInO 2 sintered at 920 °C for 4 h exhibits a relative density of 85.3 ± 0.2 % and dielectric properties, namely, ε r ∼ 9.6 ± 0.01 (15.2 ± 0.1 GHz), Q × f = 39,600 ± 2000 GHz, and τ f ∼ 9.8 ± 2 ppm/°C. The dielectric properties were investigated by chemical bond theory, and results indicate that the τ f value is closely related to the bond ionicity. The good chemical compatibility of LiInO 2 ceramics with silver electrodes makes it a potential material for LTCC technology. [ABSTRACT FROM AUTHOR]

Two garnet-type rare-earth-free ceramics, Ca 3 M 2 SiGa 2 O 12 (M = Sn and Zr), were prepared through a solid-state reaction method. The relationship between crystal structure and microwave dielectric properties was investigated. The larger deviation of ε r from ε theo in Ca 3 Zr 2 SiGa 2 O 12 could be ascribed to the rattling Zr4+. The increase in packing fraction and the decrease in FWHM enhance the Q × f value by substituting Zr4+ with Sn4+. The smaller oxygen bond valence in Ca 3 Zr 2 SiGa 2 O 12 indicates a smaller τ f value. Good microwave dielectric properties are obtained with ε r = 9.14 ± 0.02, Q × f = 106,800 ± 1700 GHz and τ f = -45.8 ± 1.8 ppm/°C for Ca 3 Sn 2 SiGa 2 O 12 and ε r = 11.98 ± 0.03, Q × f = 84,200 ± 1500 GHz, and τ f = -32.8 ± 1.4 ppm/°C for Ca 3 Zr 2 SiGa 2 O 12. Furthermore, near-zero τ f values of +5.7 ± 1.9 ppm/°C and +4.5 ± 1.6 ppm/°C appear in 0.95Ca 3 Sn 2 SiGa 2 O 12 -0.05CaTiO 3 and 0.96Ca 3 Zr 2 SiGa 2 O 12 -0.04CaTiO 3 , respectively. [ABSTRACT FROM AUTHOR]

Two garnet-structured microwave dielectric ceramics of A 3 Y 2 Ge 3 O 12 (A = Ca, Mg; called CYG and MYG, respectively) were synthesized. CYG was crystallized in a normal cubic garnet structure with Ca2+ fully occupying the dodecahedral (A) site, whereas MYG was an inverse garnet with mixed distribution of Mg2+/Y3+ at the A site. The difference in ionic occupation resulted in anomalies in microwave dielectric properties, with dielectric constant (ε r) = 14.1, quality factor (Q × f) = 12,600 GHz and positive temperature coefficient of resonant frequency (τ f) =120.5 ppm/°C for MYG ceramic and ε r = 10.8, Q × f = 97,126 GHz and τ f = −40.6 ppm/°C for CYG ceramic. The large deviations in measured ε r from theoretical ε th possibly resulted from the garnet structural constraints leading to 'rattling' Mg2+ and Y3+ in A site of MYG. Infrared reflectivity spectra analysis revealed ion polarization contributed mostly to the permittivity of both ceramics in microwave frequency ranges. [ABSTRACT FROM AUTHOR]

Electrocaloric refrigeration material with good comprehensive performance such as large temperature change (ΔT), coefficient of performance (COP) and electrocaloric coefficient (ΔT/ΔE), is very attractive in the design of commercial refrigeration devices. Here, a large positive (ΔT ∼ 12.3 K with ΔS ∼ 13.6 J K−1kg−1 at 293 K) at 10 kHz and negative EC effects (ΔT ∼ - 5.8 K with ΔS ∼ - 4.5 J K−1kg−1 at ∼ 425 K) at 100 Hz are obtained in the Nb-doped Pb 0.99 (Zr 0.65 Sn 0.3 Ti 0.05) 0.98 O 3 antiferroelectric thin film by using a sol-gel route. Moreover, the large positive and negative EC effects are sensitive and dependent to the applied frequencies. As the applied frequency increases, the positive EC effect intends to increase. However, the negative EC effect intends to decrease as the applied frequency increases. This interesting phenomenon is ascribed to the co-coupling between the phase-transition (nanoscale tetragonal transferring into rhombohedral along the direction which is vertical to the surface of the thin film, namely the [111]) & defect dipoles. Moreover, the COP (3.37) and ΔT/ΔE (0.01 K⋅cmkV−1) are also comparable to those of previous research works. These breakthroughs and findings enable the Nb-doped PZST thin film an ideal candidate for application of next-generation solid-state cooling devices. [ABSTRACT FROM AUTHOR]

Nowadays, it is urgent to explore advanced and eco-friendly energy storage capacitors based on lead-free relaxor ferroelectric (RFE) ceramics in order to meet the ever-increasing requirements in pulsed power systems. BaTiO 3 (BT)-based RFE ceramics are considered as ones of the best high-temperature energy storage materials due to their good thermal stability. However, relatively low recoverable energy storage density (W rec <5 J/cm3) has been a key bottleneck restricting the practical applications of them. Here, a novel strategy is proposed to create highly dynamic PNRs and the intrinsic conduction by introducing Bi(M 1-0.015 x Ta 0.015 x)O 3+0.015 x (BMO-Ta, M=Mg 2/3 Ta 1/3) to BT matrix. As a consequence, the designed (1- x)BT- x (BMO-Ta) ceramics exhibit dramatically enhanced energy storage properties including ultrahigh W rec and efficiency (η), because of the coexistence of very slim polarization hysteresis (P-E) loops, large polarization difference (Δ P) and giant dielectric breakdown electric strength (E b). W rec and η of the x =0.25 ceramic reach up to 9.03 J/cm3 and 95.2% under 720 kV/cm, respectively. Furthermore, it shows excellent temperature/frequency/cycling stability over a wide range of 20−200 °C, 1−500 Hz and 1−3.3 × 105 cycles, respectively (the variations of W rec and η are < 3% and < 4%, respectively). The findings in this paper not only indicate excellent comprehensive properties achieved in the novel (1- x)BT- x (BMO-Ta) system, but also provide an effective approach to explore advanced energy storage capacitors in other lead-free ceramic systems. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract The AgNbO 3 antiferroelectric (AFE) ceramics have attracted increasing attention for their high energy storage performance and environmentally friendly characters. In this work, Ag 1–2 x Ba x NbO 3 ceramics were successfully prepared by the conventional solid-state reaction method. The effect of Ba-modification on phase structure, microstructure, and electric properties was systematically investigated. The introduction of Ba2+ ion led to complex cell parameter evolution and significant refinement of grain size. Room temperature dielectric permittivity increased obviously from ~260 for the pure AgNbO 3 counterpart to ~350 for those after adding a small amount of Ba element. Slim P-E hysteresis loops with improved AFE phase were achieved after Ba modification, due to the decrease of tolerance factor. A high recoverable energy density up to 2.3 J/cm3 with energy efficiency of 46% can be obtained for the composition of Ag 0.96 Ba 0.02 NbO 3 , in correlation with the enhanced AFE stability, reduced P r , increased P m and decreased Δ E. Moreover, the Ag 0.96 Ba 0.02 NbO 3 ceramics also exhibited excellent temperature stability in both energy density and efficiency with small variation of < 5% over 20–120 ℃. The results suggest that the electric properties of AgNbO 3 system can be largely tuned after Ba modification, making it a promising candidate for energy storage applications. [ABSTRACT FROM AUTHOR]

In this paper, a new type of lead-free ceramic of Sr 4−x Ba x SmFe 0.5 Nb 9.5 O 30 (x = 0, 0.25, 0.5, 0.75 and 1, abbreviated as SBSFN) was prepared by high-temperature solid-phase synthesis. With the increase of x, the packing fraction in the unit cell increases, the vacancy decreases, and the orthogonal phase transforms into the tetragonal phase. The XRD and refinement results show the distortion in the BO 6 octahedron variety as the vacancy decreases. When x increases from 0.5 to 1, and the peak value of the dielectric constant (ε r) increases from 215 to 665 (10 kHz). With the fluctuation of the composition, the relaxation phenomenon is obvious. The impedance data show that there are crystal grains and grain boundaries at high temperature, and all samples undergo a relaxation thermal activation process. The breakdown field strength and remnant polarization of the ceramics increase with increasing x, which indicates that the ferroelectric properties of these ceramics improve. • The decrease of A-site vacancy make phase transform and decreases the BO6 octahedron distortion. • The decrease of A-site vacancy increases the relaxation ferroelectricity. • The decrease of A-site vacancy increases the dielectric constant. [ABSTRACT FROM AUTHOR]

Crystal structure, piezoelectric, and dielectric properties were investigated in the new lead-free BKT-based piezoelectric ceramics of (1− x)( Bi1/2 K1/2) TiO3- x Bi( Mg2/3 Nb1/3) O3. The morphotropic phase boundary (MPB) of the system between tetragonal and rhombohedral phases lies near the composition of x = 0.02. The optimal piezoelectric property of small-signal d33 is much enhanced to be 96 pC/N ( x = 0.01), which is higher than any other BKT-based compositions. By the introduction of Bi( Mg2/3 Nb1/3) O3, the ceramics exhibit a lower coercive field EC. In addition, a relaxor-like behavior with a frequency-dependent Curie temperature Tm is observed, and high Curie temperature Tm around 380°C is obtained in the investigated system. This study suggests that the piezoelectric properties of BKT can be significantly improved by the means of Bi( Mg2/3 Nb1/3) O3 substitution. [ABSTRACT FROM AUTHOR]

Abstract: Perovskite structure (1 − x)BaTiO3–xBiAlO3 (BT–xBA, x = 0.05, 0.08 and 0.1, corresponding to BT–5BA, BT–8BA and BT–10BA, respectively) ceramics were prepared by a solid state reaction route. Crystal structure of BT–xBA ceramics was determined by using XRD. Dielectric properties were studied as a function of temperature at different frequencies, which indicated that the phase transition temperature (T m) decreased with increasing x. With increasing temperature, thermal expansion dl/l increased while thermal expansion coefficient α had weak concentration dependence. The Burns temperature was much higher than the transition temperature T m for the BT–5BA and BT–10BA ceramics. Polarization hysteresis loops (P–E), electrostrictive (S–E) and S versus P 2 (S–P 2) at different temperatures were displayed. P max slightly decreased due to thermally activated leakage current, meanwhile, S max decreased at above T m with the contribution of ferroelectric domain reorientation decreased. The electrostrictive coefficient Q value was clearly larger than that of lead-based electrostrictors at room temperature. Furthermore, it exhibited a slim loop with negligible hysteresis and a subtle linear feature at higher temperature. [Copyright &y& Elsevier]

Abstract: (1−x)BaTiO3–xBi(Zn0.5Zr0.5)O3 [(1−x)BT–xBZZ, 0.01≤x≤0.09] lead-free piezoelectric ceramics were prepared by solid-state reaction method. The effects of Bi(Zn0.5Zr0.5)O3 addition on the crystal structure and electric properties of the BaTiO3 ceramics have been investigated. X-ray diffraction demonstrated that the samples exhibited a tetragonal to pseudocubic phase transition. The lattice parameters were found to increase with increasing the amount of BZZ content. Dielectric measurements revealed that the Curie temperature (T c ) shifted to higher temperature with increasing x. Furthermore, the ceramic with x=0.01 exhibited relatively good electrical properties with d 33=195pC/N, k p =17.7%, P r =14.5lC/cm2, and E c =11.13kV/cm. [Copyright &y& Elsevier]