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The crystallographic structure, dielectric, impedance and piezoelectric properties of novel (0.67 − x)BiFeO3–0.33BaTiO3–x(Na0.5La0.5)TiO3 (NLT100x, x = 0.0, 0.02, 0.04, 0.06, 0.08) ceramics were systematically investigated experimentally. The crystallographic studies showed that different concentrations (Na0.5La0.5)TiO3 doping were well soluble with the BiFeO3 system to form a single pseudo-cubic phase solid solution. The dielectric analysis shows that the doping reduces the leakage current, suppresses the Bi volatilization, expands the dielectric peak, and leads to the evolution of relaxor behavior. Moreover, the large strain (S) of 0.255% and the normalized strain of 430 pm/V were obtained at x = 0.04 and 60 kV/cm, which is attributed to the coexistence of ferroelectric and relaxor domains favoring the domain steering. More importantly, raising the temperature can further improve the strain performance, reaching the maximum strain (Smax) value (~ 0.346%) with the maximum normalized strain of (~ 714 pm/V) at 120 °C and 50 kV/cm. The results show the potential value of the ceramics in piezoelectric actuator applications. [ABSTRACT FROM AUTHOR]

Lead-free relaxor ferroelectric (RFE) ceramics find application in a broad range of technological devices due to their large electrostrain. But few lead-free ceramics show electrostrain values of more than 1 %. Here, an extraordinary strategy to obtain giant electrostrain by manipulating defect dipoles in (Bi, Na)TiO 3 -BaTiO 3 -based RFE ceramics is developed, achieving a high electro-induced strain value of 1.68 %, with a corresponding effective piezoelectric coefficient (d * 33) of 1965 pm/V. Furthermore, the effect of defect dipoles on RFE ceramics is discussed. The defects are pinned after poling, forming defect dipoles polarization (P d) oriented along or close to the poling direction. P d significantly promotes the transformation of polar nano regions to ferroelectric domains during strain-electric field (S - E) cycles, resulting in ultra-high electrostrain. This work proposes a detailed mechanism considering defect dipoles coupling in RFE ceramics and provides a promising paradigm for achieving high electrostrain, which could be applied in designing a wide range of functional ceramics. [ABSTRACT FROM AUTHOR]

Lead-free ferroelectric ceramics have aroused widespread concerns, due to their properties of rapid charge/discharge and electric-induced strain without harming the environment. However, compared with thin-film capacitors, ceramics have a larger energy loss. In addition, the large time lag between electric field and strain also reduces its accuracy as an actuator. Therefore, the relaxor ternary solid solution (BaTiO 3 –Bi 0.48 Na 0.48 La 0.03 TiO 3 –NaNbO 3) was constructed in this work, aiming to obtain large energy storage efficiency and low time delay. The strategy and optimization aim to improve the relaxation degree and reduce the maximum permittivity temperature to room temperature, building a special crossover region where high and low dynamic polar nano regions co-existence. Thus a recoverable energy density of 1.24 J/cm3 under a low electric field (135 kV/cm) and a high energy storage efficiency (96%) are obtained and low hysteresis electrostriction with a large electrostriction coefficient (Q 33 = 0.0367 m4/C2) is also achieved in this system. This work suggests that this system can be considered promising materials as high-efficiency capacitors and high-precision actuators. It also attracts interest in the basic research on the dynamic changes of polar nano regions. [ABSTRACT FROM AUTHOR]

Dielectric capacitors are widely used in pulse devices because of their fast charge/discharge speed. However, the low energy storage density limits their application. In this work, (1 − x)(Bi0.5Na0.5)0.94Ba0.06Ti0.99(Y0.5Nb0.5)0.01O3-xKNbO3 (BNBTYN-100xKN) lead-free relaxor ferroelectric ceramics were fabricated via a solid-state sintering technique. K+ and Nb5+ were completely diffused into the BNBTYN lattice and formed solid solutions. The incorporation of KNbO3 reduced the symmetry of BNBTYN-100xKN ceramics and destroyed the long-range ordered ferroelectric domains, leading to thinning of hysteresis loops. The relaxor degree increased with the KN content, resulting in the improvement of efficiency. Therefore, using BNBTYN-5KN ceramics an energy storage density of 1.246 J cm−3 and an efficiency of 78.7% at 104 kV cm−1 were obtained. In addition, the BNBTYN-5KN ceramics exhibited this energy storage density with outstanding temperature stability (in the range of 20–120 °C) and excellent fatigue resistance. These results reveal that BNBTYN-5KN ceramics is a promising material for energy storage. [ABSTRACT FROM AUTHOR]

Tribismuth titanium niobium oxide (B 3 TiNbO 9 , BTNO) is one of the Aurivillius phases with the highest Curie temperature (T c), but its piezoelectric coefficient (d 33) is poor. When x = 0.045, high-temperature piezoelectric ceramics with d 33 of 11.9 pC/N and T c of 916.7 °C were prepared by (Mn 1/3 Ta 2/3)(4+ ω)+ modification of Ti4+ at B-site of Bi 2.99 (Li 0.5 Sm 0.5) 0.01 Ti 1- x (Mn 1/3 Ta 2/3) x NbO 9. The substitution will aggravate the distortion of BO6 octahedron due to the displacement of oxygen ions. The existence of Mn3+ in the dopant will act as an oxygen vacancy trap and then increase the resistivity. As a result, BTNO ceramics have enhanced piezoelectric properties as well as temperature and cycle stability. This work provides a theoretical basis for better high-temperature piezoelectric properties of A/B co-doped Aurivillius phase ceramics in the future. [ABSTRACT FROM AUTHOR]

A series of bismuth layer structured ferroelectrics (BLSFs) Bi 3- x (Li 0.5 Sm 0.5) x TiNbO 9 (abbreviated as BTNO-100 x LS, x = 0, 0.01, 0.02, and 0.03) high temperature piezoelectric ceramics were prepared by solid state reaction sintering. The microstructure, piezoelectric properties, and electrical conductivity of the sintered ceramics were studied systematically. The introduction of (Li 0.5 Sm 0.5)2+ ions does not change the bismuth layered structure obviously, but it will overmelt and affect its comprehensive properties with the increase of doping content. At last, the piezoelectric coefficient (d 33) of ∼9.6 pC/N and the Curie temperature (T c) is 921.3 °C, which shows good temperature stability and cycle stability, and the mechanical quality factor (Q m) reaches 2694.3 for x = 0.01 composition. These results show that BTNO-1LS is an excellent candidate for high temperature piezoelectric ceramics. [ABSTRACT FROM AUTHOR]

A series of lead-free (Bi 0·5 Na 0.5) 0.84 Sr 0·16 Ti 1- x (Y 0·5 Nb 0.5) x O 3 (abbreviated as BNST-100 x YN) relaxor ferroelectric ceramics were prepared by solid state reaction sintering. The micro morphology, dielectric properties, and energy storage properties of the ceramics with increasing doping content were systematically studied, and their conductive mechanism was also studied. The perovskite structure was not significantly changed with the addition of (Y 0·5 Nb 0.5)4+ complex ions, but it led to a certain amount of flake grains appear and element precipitation with increasing composition. And the larger dielectric breakdown strength (DBS) and lower remanent polarization (P r) were attained with the recoverable energy storage density (W rec) of ~1.0433 J/cm3 for x = 0.04 composition. In addition, it showed outstanding dielectric temperature stability and cycle stability. These results indicated that BNST-4YN ceramics are an excellent candidate for energy storage device and temperature-stable dielectric equipment. [ABSTRACT FROM AUTHOR]

In this work, (0.64- x)Bi 0.5 Na 0.5 TiO 3 - 0.36Sr 0.7 Bi 0.2 TiO 3 - x (K 0.5 La 0.5)(Ti 0.9 Zr 0.1)O 3 lead-free piezoceramics were designed and fabricated by a conventional solid-phase sintering process. It is found that large strains (0.33 %), low hysteresis coefficients (32 %), and large dynamic d 33 * (367 p.m./V) were obtained at x = 0.01. The large strain originates from the reversible transition of the relaxor to the long-range ferroelectric order in the electric field. When the ferroelectric and relaxor phases coexist in a proper ratio, they can provide a favorable condition for the easier movement of the domains and improve the strain properties. In addition, after 105 cycles, the bipolar strain loop of x = 0.01 content changed slightly, demonstrating excellent fatigue resistance. This work provides a new way to design piezoelectric ceramics with large strain and low hysteresis. [ABSTRACT FROM AUTHOR]

Lead-free ceramics ((Bi0.5Na0.5)0.7(Sr0.7Bi0.2)0.3)1-xSmx)TiO3 (x = 0.0, 0.005, 0.01, 0.02, 0.03) with a novel phase boundary structure were successfully synthesized. All samples sintered well and shown pure perovskite structure. The doping of Sm3+ inhibits the grain growth and enhanced the relaxor properties. Besides, the activity of polar nanoregion (PNRs) is improved. Ferroelectric analysis showed that proper Sm3+ doping played a pegging role on the saturated polarized Pm, leading to a higher and slimmer P-E loop. As a result, a large energy storage density (~ 1.25 J/cm3) with high energy efficiency (~ 73%) were achieved at x = 0.005 under an electric field of 90 kV/cm. Further, the sample was found to have good temperature stability between room temperature and 110 °C. This study shows that ceramic material has great potential for the application of high-temperature stability energy storage capacitors. [ABSTRACT FROM AUTHOR]

(Bi0.5Na0.5)0.94Ba0.06Ti1−x(Y0.5Nb0.5)xO3 (abbreviated as BNTBT-100xYN) lead-free relaxor ceramics were designed and prepared using a traditional solid-state sintering technique. The influences of the introduction of (Y0.5Nb0.5)4+ complex ions for the dielectric properties and energy storage performances of BNTBT-100xYN ceramics were systematically studied. All samples exhibited a typical pseudo-cubic symmetry structure and obtained the dense microstructure with the uniform distribution of all elements. The ergodic relaxor behavior of all ceramics was observed and revealed a trend of increase as a function of composition. It accelerated the improvement of the temperature stability of the dielectric constant. All samples showed a single grain conduction mechanism and the activation energy decreased with the addition of composition. It is related to the generation of oxygen vacancies induced by the defect dipoles. BNTBT-6YN ceramic revealed excellent dielectric temperature stability within the temperature range from 87 to 479 °C and the loss tangent less than 0.05 between 25 °C and 474 °C. Besides, a high recoverable energy density of ~ 0.91 J/cm3 with the corresponding efficiency of ~ 78.5% at applied 115 kV/cm field was achieved for BNTBT-5YN ceramic. Hence, BNTBT-5YN and BNTBT-6YN ceramics will become one of the outstanding dielectric ceramics for the electronic components. [ABSTRACT FROM AUTHOR]

(1- x)[0.94(Bi 0.5 Na 0.5)TiO 3 -0.06BaTiO 3 ]- x Ba(Sn 0.70 Nb 0.24)O 3 (abbreviated as BNTBT-100 x BSN) lead-free ceramics were fabricated with a relative density greater than 96 %, and the structure as well as performance were tested. BNTBT-100 x BSN ceramics are pseudo-cubic perovskite structure, with dense surface morphology. Doping BSN can effectively reduce the dielectric loss of ceramics and increase the relaxation properties to a certain extent. The randomly distributed ferroelectric phase was replaced by polar nano regions, thereby improving the electro-strain and energy storage performance of the system. The largest electro-strain and the corresponding normalized strain (d 33 *) reach ~ 0.43 % and 633 pm/V respectively in the BNTBT-1BSN ceramic. The largest effective energy storage density reaching ~ 1.28 J/cm3 was tested in BNTBT-2BSN. BNTBT-100 x BSN ceramics provide a feasible idea for the systematic research of lead-free ferroelectrics and improvements in electro-strain and energy storage applications. [ABSTRACT FROM AUTHOR]

Lead-free antiferroelectric (AFE) ceramic materials have attached increasing attention in application of high-power capacitors for the past few years, due to their high energy storage density and environmental protection. However, the related applications are seriously restricted because of the limited number of environment friendly AFE candidate materials, high cost and low energy storage efficiency. In this work, the A-site ion Sm3+ doped 0.88NaNbO 3 -0.12Sr 0·7 Bi 0·2 TiO 3 lead-free AFE P phase ceramics (0.88Na 1-3 x Sm x NbO 3 -0.12Sr 0·7 Bi 0·2 TiO 3 , abbreviated as NN-SBT-100 x Sm) were prepared and characterized. With the increase of Sm doping amount, a relaxor-like behavior was found in the dielectric-temperature curves of NN-SBT-100 x Sm, indicating the AFE orthorhombic P phase is gradually replaced by an AFE orthorhombic R phase. As a result, double-like and slim P - E curve with near-zero residual polarization and suppressed hysteresis loss was obtained at x > 0.01. More encouragingly, a good discharge energy storage density (W rec = 3.58 J/cm3) and a high efficiency (η = 82%) at a low electric field (E = 200 kV/cm) has been recorded simultaneously for NN-SBT-2Sm relaxor AFE ceramic, which are better than the other lead-free energy storage ceramics under the same E. In addition, the energy storage properties of NN-SBT-2Sm ceramics exhibit outstanding temperature and frequency stability. These results indicate that NN-SBT-2Sm relaxor AFE ceramic has a great practical value in pulse power capacitors. [ABSTRACT FROM AUTHOR]

A series of Bi 0.5- x Er x Na 0.4 K 0.1 TiO 3 (BNKT- x Er) ceramics were designed and fabricated, the dopant effects on dielectric, piezoelectric and photoluminescence properties were studied. The results show that the piezoelectric property of BNKT can be enhanced by a trace amount of Er dopant, which is also reflected in the large linear electrostrain (S uni = 0.29%, under 55 kV/cm) achieved in BNKT-0.0025 Er. On the other hand, higher Er content can produce excellent dielectric temperature stability, with △ ԑ / ԑ 150 °C < ±15% over temperature range of 90∼510 °C. Meanwhile, all BNKT- x Er ceramics exhibit good photoluminescence properties, which may open new applications of these multifunctional ceramics. [ABSTRACT FROM AUTHOR]

Dielectric ceramics for capacitors have attained significant attention in current time owing to their large power densities and fast charge/discharge rates. Lead-free [(Bi0.50Na0.40K0.10)0.94Ba0.06]1-xLaxTi0.975Ta0.025O3 (abbreviated as BNKBTT-100xLa) relaxor ceramics are prepared using mixed-oxide technique. All ceramics are revealed a pseudo-cubic structure using X-ray diffraction technique. The long-range order existing in BNKBTT-100xLa ceramics is found to reduce with increasing composition. As a result, a highly effective energy storage density (Wrec) ~ 1.558 J/cm3 and efficiency (η) ~ 88.46% is achieved in BNKBTT-2La ceramic. In addition, BNKBTT-2La composition is fatigue-free up to 105 cycles. Also, BNKBTT-4La ceramic exhibits a dielectric constant (ε') ~ 2281 near 150 °C with Δε'/ε'150 °C below 15% over a large range from 39 to 383 °C, showing an outstanding dielectric temperature stability. Therefore, BNKBTT-2La and BNKBTT-4La ceramics are outstanding for energy density and thermally stable dielectric permittivity, respectively, for the device applications. [ABSTRACT FROM AUTHOR]

In this study, (1- x)(0.66Bi 0.5 Na 0.5 TiO 3 –0.34Bi 0.2 Sr 0.7 TiO 3)– x K 0.5 Nd 0.5 TiO 3 (BNBST– x KNT) ceramics were designed and synthesized, and they present significantly enhanced dielectric temperature stability and energy storage properties. The BNBST–0.06KNT composition exhibits a remarkable dielectric stability, as reflected in its stable dielectric constant (△ ԑ / ԑ 150 °C < ±15%) over a broad temperature range (25–401 °C). BNBST–0.02KNT achieves a high energy storage density W rec = 1.2 J/cm3 under 110 kV/cm with an energy storage efficiency η of 76.9%, and the improved energy storage property originates from the improved breakdown field strength and decreased hysteresis behavior. The electrical conductivity and relaxation behaviors of BNBST– x KNT were also analyzed via impedance spectroscopy. [ABSTRACT FROM AUTHOR]

A ternary solid solution of Bi 0.5 Na 0. 5 TiO 3 –Bi 0.5 K 0. 5 TiO 3 –Bi(Mg 2/3 Ta 1/3)O 3 (BNKT- x BMT) lead-free electroceramics was synthesized by a solid-state reactive sintering technique. The electrostrain, dielectric, and ferroelectric properties as well as the impedance characteristics and the microstructure were systematically assessed. With the increase of BMT, the BNKT- x BMT ceramics gradually transformed from non-ergodic relaxor phase to ergodic relaxor phase, manifested as the ferroelectric-to-relaxor temperature (T F-R) shifts towards below room temperature. Additionally, the ferroelectric hysteresis curves became pinched, and the strain curve changed from butterfly-shaped into sprout-shaped. At the ergodic relaxor composition of x = 0.04, a large electrostrain value (S = 0.4%; under an electric field of 60 kV/cm, d 33 * = 632 pm/V) was achieved, which is mainly attributed to the electric-field-induced transition from the ergodic relaxor phase to the ferroelectric phase. [ABSTRACT FROM AUTHOR]

The high storage energy density (W rec) and conversion efficiency (η) for lead-free ceramics have been attained significant interest in recent times for electronic devices. Enhanced W rec and stable fatigue properties are examined for lead-free 0.94Bi 0·50 (Na 0·78 K 0.22) 0.50 Ti 1- x (Al 0·50 Nb 0.50) x O 3 -0.06BaZrO 3 (for 0 ≤ x ≤ 0.05) ceramics, synthesized using the solid-state reaction method. Crystal structure and lattice dynamics are revealed by the X-ray diffraction and Raman scattering techniques. Highly compact ceramics is obtained with decreasing average grain size from 0.94 ± 0.23 μm (for x = 0) to 0.76 ± 0.31 μm (for x = 0.05) as a function of composition. A high W rec ~1.32 J/cm3 and η ~76.60% is achieved for x = 0.04 ceramic at room temperature with applied 95 kV/cm. In addition, W rec ~1.40 J/cm3 and η ~86% are perceived with a 90 kV/cm at 80 °C. Also, it is obtained as a fatigue-free property for x = 0.04 composition ceramic up to 105 cycles. Hence, this improvement in energy density performance and stable fatigue resistance for x = 0.04 dielectric ceramic is expected for practical applications in many electronic appliances. [ABSTRACT FROM AUTHOR]

(1- x)[(Na 0.5 Bi 0.5) 0.84 Sr 0.16 ] 0.98 La 0.01 TiO 3 - x K 0.5 Na 0.5 NbO 3 (abbreviated as NBSLT-100 x KNN) lead-free perovskite relaxor ferroelectric ceramics are synthesized through the conventional solid-state reaction. The effects of KNN on the ceramic polycrystalline structure, dielectric temperature stability, and energy-storage characteristics are studied systematically. All samples exhibit a single perovskite structure and compact surface morphology. Thermally stable dielectric permittivity (ε ′) is obtained from 62 to 331 °C range for NBSLT-5KNN ceramic with ε ′ ~ 2286 at 150 °C less than ± 10% fluctuation rate. The addition of KNN refines the hysteresis loops and gradually increases the dielectric breakdown strength, which endows NBSLT-5KNN ceramic with the best energy-storage performance compared to other compositions. A high effective energy-storage density (W rec) ~ 1.234 J/cm3 with efficiency (η) ~ 74.7% are acquired at 90 kV/cm. The energy-storage performance is revealed an excellent fatigue resistant stability. Hence, the introduction of KNN makes NBSLT-5KNN ceramic an outstanding competitor for energy-storage equipment applications. [ABSTRACT FROM AUTHOR]

Energy density and fatigue resistance properties were investigated for lead-free Na 0.46 Bi 0.46 Ba 0.05 La 0.02 Zr 0.03 Ti 0.97- x Sn x O 3 (for 0 ≤ x ≤ 0.15) ceramics, synthesized via solid-state reaction technique. Perovskite pseudo-cubic crystal structure was revealed for all ceramics using X-ray diffraction. Polarization and current density versus electric field were perceived and suggested the relaxor behavior with increasing composition. A high storage energy density ~1.58 J/cm3, and conversion efficiency ~71.7% at ~110 kV/cm applied field was obtained for x = 0.03 composition at room temperature. Energy storage density was revealed ~1.53 J/cm3, and efficiency ~88.6% at 110 °C with a 100 kV/cm applied field. In addition, ceramic x = 0.03 was fatigue-free from 1 to 105 cycles. Hence, the composition x = 0.03 might be applicable for high energy storage devices. [ABSTRACT FROM AUTHOR]

Among Aurivillius-phase ferroelectric ceramics, CaBi2Nb2O9 is considered as the best candidate with potential applications in ultrahigh-temperature piezoelectric devices due to the highest Tc (∼940 °C). This paper reports that BiMn co-substitution at A and B sites gives rise to dramatic enchantments in ferroelectricity, piezoelectricity, and electrical resistivity of CaBi2Nb2O9 ceramics. The optimum composition (Ca0.97Bi2.03Nb1.99Mn0.01O9) with a Tc of 953 ± 3°C shows a high ferroelectric remnant polarization (Pr), field-induced strain (S33), piezoelectric activity d33 and d 33 ∗ with values of ∼11.1 µC/cm2, 4.9 × 10−4, 20.8 and 26.1 pC/N, respectively, which are about two to three times those of CaBi2Nb2O9. Significant ferroelectric remnant polarization (Pr = 11.1 µC/cm2), field-induced strain (S33 = 4.9 × 10−4), and piezoelectric activity (d33 = 20.8 pC/N, d 33 ∗ = 26.1 pC/N) are simultaneously induced in ultrahigh Tc CaBi2Nb2O9 piezoceramics by BiMn substitution. [ABSTRACT FROM AUTHOR]

0.94(Bi 0.5 Na 0.5)(Y 0.5 Ta 0.5) x Ti 1- x O 3 -0.06BaTiO 3 lead-free piezoelectric ceramics were prepared by a conventional solid-state reaction method to study their excellent electro-strain properties and energy storage characteristics systematically. All ceramics exhibited a dense surface morphology. The introduction of (Y 0.5 Ta 0.5)4+ complex ions destroyed the long-range ferroelectric order, which reduced the T F-R to the operating temperature, resulting in an easier field-induced transition between relaxor and ferroelectric phase. Therefore, for x = 0.01 component attained unipolar strain of 0.37% under 52 kV/cm, and the corresponding normalized strain d 33 * was 708 pm/V. Besides, the destruction of the ferroelectric phase also induced a pinched hysteresis loop and the maximum storage density of 1.215 J/cm3 with the efficiency of 68.7% obtained at 98 kV/cm for BNYT30 ceramics. These all demonstrated that the doping of complex ions (Y 0.5 Ta 0.5)4+ made the BNT-BT an outstanding candidate for actuators and energy storage devices. [ABSTRACT FROM AUTHOR]

Polycrystalline (1- x)[(Na 0.5 Bi 0.5) 0.95 Ba 0.05 ] 0.98 La 0.02 TiO 3 - x K 0.5 Na 0.5 NbO 3 systems were prepared using the solid-state reaction technique. Modification of (Na 0.5 Bi 0.5) 0.95 Ba 0.05 ] 0.98 La 0.02 TiO 3 ceramic with a proper amount of K 0.5 Na 0.5 NbO 3 can effectively improve the temperature-stable of dielectric properties. A variation in dielectric constant is maintained smaller than ±5% from 80 to 300 °C accompanied with a low dielectric loss (≤0.04). The relaxor properties of the doped samples are significantly enhanced. A high energy storage density of 1.1 J/cm3 and efficiency ~80% at 90 kV/cm are achieved in the x = 0.05 composition. Hence, the as-prepared ceramics might be practical in dielectric constant which can work stably at a high temperature range and pulsed capacitors. [ABSTRACT FROM AUTHOR]

Abstract: A new type of (0.7−x)Bi0.5Na0.5TiO3‐0.3Sr0.7Bi0.2TiO3‐xLaTi0.5Mg0.5O3 (LTM1000x, x = 0.0, 0.005, 0.01, 0.03, 0.05 wt%) lead‐free energy storage ceramic material was prepared by a combining ternary perovskite compounds, and the phase transition, dielectric, and energy storage characteristics were analyzed. It was found that the ceramic materials can achieve a stable dielectric property with a large dielectric constant in a wide temperature range with proper doping. The dielectric constant was stable at 2170 ± 15% in the temperature range of 35‐363°C at LTM05. In addition, the storage energy density was greatly improved to 1.32 J/cm3 with a high‐energy storage efficiency of 75% at the composition. More importantly, the energy storage density exhibited good temperature stability in the measurement range, which was maintained within 5% in the temperature range of 30‐110°C. Particularly, LTM05 show excellent fatigue resistance within 106 fatigue cycles. The results show that the ceramic material is a promising material for temperature‐stable energy storage. [ABSTRACT FROM AUTHOR]

Manganese-doped Ba0.925Ca0.075TiO3 lead-free piezoelectric ceramics (abbreviated as BCT) with high mechanical quality factor were synthesized by conventional solid-state reaction method. The effects of excess Ba on the crystal structure, microstructure, and electrical properties of the ceramics were systematically investigated. X-ray diffraction and Raman spectra revealed that Ca2+ ions were pushed from Ba sites to Ti sites of BCT when 1.5 mol% extra Ba2+ ions were added after sintering. The grain size of the ceramics was decreased by adding extra Ba2+ ions. The mechanical quality factor and resistivity of the ceramics decreased dramatically when the excess Ba was more than 1.5 mol%. High piezoelectric coefficients ( d33 = 150-190 pC/N ) and high mechanical quality factors ( Qm = 1 000-1 200 ) were obtained in the ceramics when the excess of Ba was between 0.5 mol% and 1 mol%. These results indicated that the properties of BCT ceramics could be tailored by adjusting the content of Ba. [ABSTRACT FROM AUTHOR]

Abstract: The (1−x)(0.8Bi1/2Na1/2TiO3–0.2Bi1/2K1/2TiO3)−xBiMg2/3Nb1/3O3 (100xBMN) ternary solid solutions were designed and prepared using a conventional solid‐state reaction. Temperature and compositional dependent ferroelectric, piezoelectric, dielectric features, and structural evolution were systematically studied. At the critical composition of 2BMN, a large bipolar strain of 0.43% was achieved at 55 kV/cm, and the normalized strain reaches to 862 pm/V at a low driving electric field of 40 kV/cm. It was found that the substitution of BiMg2/3Nb1/3O3 induces a transformation from ferroelectric to relaxor phase by disrupting the long range ferroelectric order. Therefore, as the external electric field was applied, a relaxor‐ferroelectric phase transition will be induced. This is contributed to the giant strain. The results above suggest that such a ternary composition is a promising candidate for application to actuator. [ABSTRACT FROM AUTHOR]

Novel (1– x )(0.94Bi 0.5 Na 0.5 TiO 3 –0.06BaTiO 3 )– x Sr 0.7 La 0.2 TiO 3 ternary lead-free ceramics (BNBT– x SL, x  = 0.00–0.08) were fabricated by the widely used solid-state sintering technique. The crystal phase, microstructure, dielectric relaxation, piezoelectric, and electromechanical properties of each composition were systematically analyzed. It is found that the addition of SL has little effect on the crystal phase and grain morphology, but it can remarkably improved the relaxation property of the ceramic sample and gave rise to favourable dielectric properties in a wide range of temperatures. In addition, as the SL content increases, the ferroelectric to relaxor temperature ( T F-R ) is adjusted to below ambient temperature. More importantly, the decay of ferroelectric phase resulted in a significant increase in strain value: the large strain of 0.5% with normalized strain of 625 pm/V was obtained at 80kv/cm and x  = 0.04. Finally, the composition exhibited high strain of temperature insensitivity range from room temperature to 100 °C, the strain value remained above 0.4% and kept within 5%. The results are due to the coexistence of rhombohedral polar-nanoregions (PNRs) and tetragonal PNRs during the relaxor region. This result is of great importance to the developments of temperature-insensitive strain sensors and actuators. [ABSTRACT FROM AUTHOR]

x% mol MnO2-doped Ba0.925Ca0.075TiO3 ceramics (abbreviated as BCT-Mn x, x=0-1.5) were synthesized by conventional solid-state reaction method. The effects of MnO2 addition and (Ba+Ca)/Ti mole ratio (A/B ratio) on the microstructure and electrical properties of the ceramics were investigated. The internal bias filed Ei was determined from the asymmetrical polarization hysteresis loops and found to increase with the doping concentration of MnO2. High mechanical quality factors ( Qm>1200) and low dielectric loss (tanδ<0.5%) were found in the BCT-Mn0.75 and BCT-Mn1.0 ceramics with Ei>3 kV/cm, meanwhile, the piezoelectric and electromechanical properties were found to decrease compared with the pure BCT, exhibiting a typical characteristic of 'hard' behavior. Of particular interest is that the microstructure of BCT-Mn0.75 ceramics could be controlled by changing the A/B ratio, where enhanced piezoelectric coefficient d33 on the order of 190 pC/N was obtained in the BCT-Mn0.75 ceramics with A/B=1.01 due to its fine-grained microstructure, with yet high Qm , being on the order of 1000. The high d33 and Qm in MnO2-doped BCT ceramics make it a promising candidate for high power piezoelectric applications. [ABSTRACT FROM AUTHOR]

Aurivillius Bi 3 TiNbO 9 has a very high Curie temperature (T c), but the piezoelectric coefficient (d 33) is very low, and the influence of ions with different radii on its performance is not clear. High temperature piezoelectric ceramics Bi 2.99 (Li 0.5 Ln 0.5) 0.01 TiNbO 9 (BTNO-1LiLn, Ln = La, Nd, Gd, and Er) were prepared by solid state reaction sintering, and its microstructure, piezoelectric properties and electrical conductivity were systematically studied. The T c of BTNO-1LiLn increases with the decrease of Ln3+ ions radii. BTNO-1LiEr obtains the highest d 33 of 10.6 pC/N. Considering the cation disorder of A-site and bismuth layer of calcium titanium layer in Aurivilius structure, the crystal structures of BTNO-1LiLa with special occupation and BTNO-1LiEr with the best performance are refined, and the source of spontaneous polarization (P s) is analyzed. It is proved that different occupation will have different effects on the high temperature piezoelectric properties and fatigue cycle properties of BTNO based ceramics. Finally, the band structure of BTNO pure ceramic based on the first principle is calculated. By comparing the activation energy and band gap width, it is indicated that (Li 0.5 Ln 0.5)2+ ions entering BTNO will form impurity energy levels and form p -type semiconductors. This study provides a theoretical basis for better performance of BTNO based high temperature piezoelectric ceramics. [Display omitted] • Discussing the effects of lanthanide ions entering into different sites on the high temperature piezoelectric properties of Bi3TiNbO9. • Analyzing the influence of lanthanide ions entering into different sites on the electrical characteristics of Bi 3 TiNbO 9. • The band structure of pure Bi 3 TiNbO 9 is calculated based on the first principle. [ABSTRACT FROM AUTHOR]

The perovskite oxides (1 − x)Bi0.5(Na0.9K0.1)0.5TiO3- xSrTi0.8Zr0.2O3 (SZT1000 x, x = 0, 0.2, 0.4, 0.6, 0.8, and 1 %) were prepared via the conventional solid-state reaction method. The room temperature ferroelectric P- E loops coordinate with polarization current density J- E curves illustrated the changes of ferroelectric domains and polar nanoregions under different driving fields exhaustively. The composition and electric field dependent strain behavior of this system were investigated to develop a lead-free piezoelectric material with a large strain response at a lower electric field. A large strain of 0.44 % (Smax/Emax = 744 pm/V) at an applied field of 50 kV/cm was obtained at the composition of 0.6 mol% SZT. Temperature-dependent hysteresis measurements reveal the primary origin of the large strain is due to the presence of a nonpolar phase at a zero field. Upon the application of an electric field, the nonpolar phase that can easily transform into a long-range ferroelectric phase, and then brings the system back to its unpoled state once the applied electric field is removed. Notably, the electric field required to deliver large strains is reduced to 40 kV/cm while the Smax/ Emax reached up to 717 pm/V, indicating that the developed material is highly promising for actuator applications. [ABSTRACT FROM AUTHOR]

Developing high performance and pollution-free energy storage devices is crucial for the development of the energy industry. The Sm(Mg 0.5 Ti 0.5)O 3 -modified (Bi 0.5 Na 0.5) 0.7 Sr 0.3 TiO 3 ((1- x)BNST– x SMT, x = 0.00–0.15)) relaxor ceramics were synthesized by using a traditional solid-state sintering method. The phase structure, microstructure, dielectric spectrum, and energy storage properties were studied. The x = 0.10 sample obtained an energy storage density of 4.33 J/cm3 under an electric field of 290 kV/cm, while the energy storage efficiency reached 80 %. In addition, the variation of energy storage density remains within ±4 % and the energy storage efficiency is above 80 % at a frequency of 1–100 Hz and a temperature of 25–120 °C, respectively, indicating that the x = 0.10 sample has good stability in both temperature and frequency. The energy storage decreases slightly with increasing temperature and frequency, which originates from the migration of intrinsic charge carriers and the weakening of the interaction force between cations and anions. In addition, the x = 0.10 sample exhibits good fatigue resistance, with little change in the ferroelectric loop after 105 cycles. This performance advantage indicates that the (1- x)BNST- x SMT ceramic systems have great potential in the field of high energy storage. [ABSTRACT FROM AUTHOR]

• BNKTT-1La ceramics achieved an excellent bipolar strain of ∼0.44 % and a large unipolar strain of ∼0.439 % at 60 kV/cm. • The unipolar strain of BNKTT-1La ceramics increased significantly to ∼0.895 % at 100 °C. • BNKTT-1La ceramics exhibited excellent fatigue resistance after 105 cycles at 65 kV/cm. Lead-free piezoelectric ceramics [(Na 0.84 K 0.16) 0.5 Bi 0.5 ] 1- x La x Ti 0.985 Ta 0.015 O 3 (BNKTT-100 x La) were synthesized by traditional solid phase reaction. The influences of La3+ doping on ceramic materials' microstructure, ferroelectric, and dielectric properties were investigated systematically. XRD patterns indicated that La3+ fully diffuse into the BNKTT lattice and form a single solid solution. SEM images showed that the surface of all samples was compact and no heterophase appeared. The ferroelectric-relaxor phase transition temperature gradually moved to low temperature with the increase of La3+ doping, which was beneficial to obtain large electro-strain. The maximum unipolar strain of BNKTT-1La ceramics can reach ∼0.439 % at 60 kV/cm corresponding to the inverse piezoelectric coefficient d 33 ∗ of ∼731 pm/V. The strain performance increased significantly to ∼0.895 % at high temperature because the ferroelectric-relaxor phase transition became easier. The BNKTT-1La ceramics showed excellent fatigue resistance after 105 cycles at 60 kV/cm. All these indicated that BNKTT-100 x La ceramics have great application prospects in piezoelectric brakes, strain sensors, and actuators. [ABSTRACT FROM AUTHOR]

Relaxor ferroelectrics are promising candidates for energy storage equipment due to their excellent energy-storage properties. Lead-free (1- x)Bi 0.38 Na 0.38 Sr 0.24 TiO 3 - x BaSnO 3 (abbreviated as BNST-100 x BS) relaxor ceramics were synthesized by a traditional solid-phase sintering method. The influences of the addition of BaSnO 3 dopants for the energy storage and dielectric temperature-stable properties of BNST-100 x BS ceramics were systemically investigated. All samples exhibited a typical pseudo-cubic symmetry structure and obtained the dense microstructure. The ergodic relaxor behavior of all ceramics was observed and revealed a trend of increase as a function of composition. All samples showed a single grain conduction mechanism and the activation energy decreased with the addition of composition. It is related to the generation of oxygen vacancies induced by the defect dipoles. BNST-2.5BS ceramic exhibited an outstanding recoverable energy density of ~1.42 J/cm3 with the corresponding efficiency of ~79.7% at 115 kV/cm field. In addition, excellent temperature-stable permittivity (43–255 °C) was obtained for BNST-7.5BS ceramic. Hence, BNST-2.5BS ceramic revealed excellent energy density properties and BNST-7.5BS exhibited outstanding temperature-stable dielectric permittivity, which was beneficial to use in energy storage equipment and other device applications. [ABSTRACT FROM AUTHOR]

(1- x)(Bi 0.5 Na 0.5) 0.94 Ba 0.06 TiO 3 - x AgNbO 3 lead-free piezoelectric ceramics (abbreviated as BNBT-100 x AN) were prepared using the conventional solid-state sintering method. The effects of the introduction of AgNbO 3 (AN) dopants for the dielectric and piezoelectric performances of BNBT-100 x AN ceramics were systematically studied. The XRD patterns and Raman spectra demonstrated that AN as a modifier was successfully diffused into the BNBT-100 x AN lattice and revealed a pseudo-cubic symmetry structure. All samples exhibited a dense surface morphology accompanied by the uniform distribution of elements. A large bipolar strain of ~0.501% and unipolar strain of ~0.481% corresponding to the normalized strain d 33 * of ~740 p.m./V were achieved for BNBT-1AN ceramic at 65 kV/cm field. The BNBT-4AN ceramic exhibited an excellent temperature-stable permittivity with the range from 59 to 380 °C and its dielectric loss was less than 0.02 between 97 °C and 329 °C. These results revealed that BNBT-100 x AN ceramics were more hopeful candidates for actuators, strain sensors, and high-temperature capacitors. [ABSTRACT FROM AUTHOR]

A series of novel Bi 0.38 Na 0.38 Sr 0.24 Ti (1- x) (Mn 1/3 Nb 2/3) x O 3 lead-free ceramics (BNST-100 x MN) were designed and fabricated. The dielectric, ferroelectric, energy-storage, electrostrain properties, and impedance performance of these materials were systematically investigated. A large strain response under low driving electric field was obtained that benefits from the enhanced relaxor-to-ferroelectric phase transition. The optimum piezoelectric stain coefficient d 33 * of 930 pm/V (under 40 kV/cm) was achieved in BNST-1MN composition. The substitution by MN dopant gave rise to a homogeneous micro-morphology with small grains that gave rise to an enhanced high breakdown strength (BDS). Slim and slanted ferroelectric hysteresis was obtained by introducing a larger amount of MN, and hence the BNST-2MN ceramic exhibits a high energy-storage density of 1.30 J/cm3 at 110 kV/cm, accompanied with an excellent fatigue-free behavior. The dielectric response exhibited a stable high temperature dielectric property with low dielectric loss. These results indicate that BNST-100 x MN ceramics are promising candidates for the actuator and energy storage applications. [ABSTRACT FROM AUTHOR]

The Na 0.325 Bi 0.395 Sr 0.245□0.035 TiO 3 + x % MnCO 3 (NBST-100 x Mn) lead-free ceramic samples had been fabricated by solid-state reaction method. Microstructure and electrical properties with the addition of MnCO 3 had been studied in detail. The NBST-4Mn showed a low hysteresis behavior with the maximum electrostrictive coefficient (Q) of 0.0294 m4/C2 and the recoverable energy storage density (W rec) of 1.3 J/cm3 at 95 kV/cm. In addition, the electrostrictive effect and energy storage ability presented outstanding temperature stability and fatigue resistance, which indicated a promising lead-free ceramic for high precise actuator. [ABSTRACT FROM AUTHOR]

0.94Bi 0.5 (Na 0.78 K 0.22) 0.5 Ti 1- x Ta x O 3 -0.06Ba 0.95 Sr 0.05 TiO 3 (BNKT-BST-100 x Ta, for x = 0,0.005, 0.010, 0.015, 0.020 and 0.025) lead-free ceramics were fabricated by the solid-state reaction technique. Microstructure, dielectric, ferroelectric and fatigue performances of BNKT-BST-100 x Ta ceramics had been systemically studied. The XRD patterns confirmed that Ta5+ ions had completely dissolved into the lattice of BNKT-BST-100 x Ta ceramics. Meanwhile, the temperature of R 3 c -PNRs (T s) was found to shift towards room temperature in dielectric permittivity curves with the introduction of Ta5+ ions. In addition, the highest unipolar strain of 0.32% with the corresponding normalized strain of 458 pm/V was obtained for x = 0.020 under the applied electric field of 70 kV/cm. The large electro-strain was cause by intrinsic effect of the crystal and the external electric field. Moreover, the excellent strain fatigue resistance indicated the prepared ceramics are promising candidates for actuators and stress sensors. [ABSTRACT FROM AUTHOR]

The high recoverable energy density (W rec) of 1.83 J/cm3 was achieved at 120 kV/cm by simply introducing 0.050 mol. % Li+ ions into the A-site of Bi 0.5 (Na 0.4 K 0.1)] 0.96 Sr 0.04 Ti 0.975 Ta 0.025 O 3 lead-free relaxor ceramics. Bi 0.5 (Na 0.4- x Li x K 0.1)] 0.96 Sr 0.04 Ti 0.975 Ta 0.025 O 3 (BNKSTT-100 x Li) ceramic samples were prepared by solid-state reaction method. The influence of Li+ ions on structure and electrical properties was analyzed in detail. XRD patterns and Raman spectra of these samples were revealed a pure perovskite-type structure. BNKSTT-100 x Li ceramics exhibited an obvious relaxor characteristic with the downshift of T F-R to ambient temperature. J - E loops confirmed the relaxor ferroelectric like nature. Leakage current density was proved to decrease with the increasing Li+ ions concentration. At the composition x = 0.050, remnant polarization (P r) kept steady while maximum polarization (P max) and breakdown strength (DBS) increased obviously, which was beneficial to the enhancement of recoverable energy density. [ABSTRACT FROM AUTHOR]

A series of (1- x)(Bi 0.5 Na 0.5) 0.94 Ba 0.06 TiO 3 - x BaSnO 3 (BNBT-100 x BSN, x = 0–20) lead-free ceramics were synthesized using a conventional high-temperature solid-state reaction route. The effects of BaSnO 3 on the dielectric, ferroelectric and energy-storage performance of BNBT-BSN were systematically investigated. Temperature dependent permittivity curves indicated the obviously enhanced relaxor ferroelectric property. The introduction of BaSnO 3 reduced the temperature corresponding to the first dielectric anomaly, which facilitated the dielectric temperature stability. △ε'/ε' 150°C varied no more than 15% within the temperature range of up to 338 °C (45–383 °C) for BNBT-15BSN. A slimed P-E loop was obtained with the remnant polarization of 0.4 μC/cm2 for BNBT-15BSN. Moreover, the breakdown field intensity of BNBT-BSN increased effectively from 80 kV/cm to 115 kV/cm. Therefore, an optimum energy-storage performance was obtained in BNBT-15BSN with the energy-storage density of 1.2 J/cm3 whose energy-storage efficiency reached 86.7%. Furthermore, the possible contributions of defect and vacancy to relaxation and conductance mechanism were discussed by studying the impedance and electric modulus. The results above indicated the BNBT-100 x BSN be a promising lead-free candidate for energy-storage capacitors. [ABSTRACT FROM AUTHOR]

A series of Bi 0.48 (Na 0.84 K 0.16) 0.48 Sr 0.04 (Ti 1- x Ta x)O 3 (abbreviated as NKS-100 x Ta) lead-free piezoelectric ceramics were fabricated using a traditional solid-state method. The structure and electrical properties of NKS-100 x Ta were investigated in detail. The composition for x = 0.01 presented an enhanced electric field induced bipolar strain of ∼0.53%, as well as the giant unipolar strain of ∼0.478% corresponding to S max / E max ∼682 p.m./V at 70 kV/cm. It is found that the ferroelectric-relaxor transition temperature (T F-R) shifted down to ambient temperature and the remnant polarization (P r) decreased with the Ta doping. It destroyed the long-range ferroelectric ordering and increased the relaxor characteristic. Therefore, the origin of giant strain was ascribed to the transformation from the ferroelectric phase to relaxor phase under the applied electric field. In addition, the well fatigue properties within 104 cycles indicated that the prepared ceramics offered extendable availability for sensors and actuators. Fig. 5. (a) Unipolar strain curves of the NKS-100 x Ta measured at 70 kV/cm with 1 Hz frequency. (b) P r , P m and d * 33 as a function of Ta content. Image 1 • A ferroelectric-to-relaxor transition is obtained by chemical modification. • The giant unipolar strain of 0.478% corresponding to S max / E max ∼ 682 pm/V at 70 kV/cm obtained at ambient temperature. • The giant strain derives from the combination of interior and extrinsic effects. [ABSTRACT FROM AUTHOR]

A series of (1- x )(0.7Bi 0.5 Na 0.5 TiO 3 -0.3Bi 0.2 Sr 0.7 TiO 3 )- x NaNbO 3 (BNT-BST-100 x NN) lead-free ceramics were fabricated using conventional solid-state reaction technique. The phase behavior, microstructure, dielectric, ac impedance and energy-storage properties of the sintered ceramics were systematically investigated. XRD patterns and surface SEM micrographs revealed the introduction of NaNbO 3 didn't change the perovskite structure of BNT-BST at low doping level. The NaNbO 3 doping gave rise to slimmer P - E loops and thus gained enhanced energy storage properties. Therefore, a maximum energy storage density of 1.03 J/cm 3 was achieved at 85 kV/cm at x = 0.01 via increasing the dielectric breakdown strength (DBS). Temperature-dependent dielectric permittivity illustrated the enhanced relaxor characteristics, implying the long-rang ferroelectric order was further damaged due to the introduction of NaNbO 3 . The results above indicate the sintered ternary ceramics can be a promising lead-free candidate for energy storage capacitors. [ABSTRACT FROM AUTHOR]

Lead-free piezoceramics (Na (1+ x )/2 Bi (1- x )/2 ) 0.94 Ba 0.06 Ti 1- x Nb x O 3 (BTN100 x ) were prepared using conventional solid-state reaction method. The structures, field- induced strain, AC impedance of sintered ceramics were investigated. The pure perovskite solid solution BTN3 exhibited giant electric-field-induced strain of 0.478% under an electric field of 70 kV/cm at ambient temperature, meanwhile, the normalized strain ( S max / E max ) reached up to 654 pm/V. The giant strain was insensitive to temperature and exhibited excellent fatigue resistance performance within 10 6 switching cycles, making it a promising candidate material for actuator applications. Complex AC impedance spectra confirmed the contribution of grain effect to resistivity behavior. The field-induced giant strain was attributed to the phase transition between ferroelectrics and relaxor ferroelectrics induced by introducing Nb 2 O 5 . [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]

(1- x )BiTi 0.5 Zn 0.5 O 3 -x(0.935Bi 0.5 Na 0.5 TiO 3 -0.065BaTiO 3 ) (abbreviated as BTZx) lead-free ceramics were prepared by using a conventional solid state reaction method and their composition and temperature dependent energy-storage properties were investigated. The addition of BiTi 0.5 Zn 0.5 O 3 sharply decreased the content of ferroelectric phase, leading to lowered remanent polarization and coercive field. A large energy storage density (W) of 1.04 J cm −3 was achieved at 95 kV cm −1 for BTZ0.916. In the high temperature region, the remanent polarization was suppressed, while maximum polarization still maintained at a high level. Significantly enhanced W of ~0.952 J cm −3 at 80 kV cm −1 was obtained with a relatively high efficiency of ~0.8, making these materials attractive in energy storage applications. [ABSTRACT FROM AUTHOR]

The development of lead-free ceramics with high energy storage density is critical due to the human health and environmental hazards of lead and the demand to miniaturize and integrate electronic devices. Nevertheless, the high applied electric field limits their use in integrated circuits. In this work, (1- x) Bi 0.5 (Na 0.82 K 0.18) 0.5 Ti 0.99 (Y 0.5 Nb 0.5) 0.01 O 3 - x NaNbO 3 (BNKTYN-100 x NN) ceramics were prepared, and excellent energy storage properties were obtained. It has revealed that NaNbO 3 dopant reduces remanent polarization and increases relaxor degree. BNKTYN-9NN ceramics has high energy storage density (W rec =1.6 J/cm3) and responsivity (ξ = W rec / E = 145.5 J/(kV•m2)) under 110 kV/cm. Meanwhile, good temperature stability (20–120 °C) and fatigue resistance (105 cycles) were also obtained in BNKTYN-9NN ceramics. In addition, doping NaNbO 3 suppresses the dielectric anomaly peak, and BNKTYN-9NN ceramics has excellent temperature-stable dielectric permittivity from 53° to 447°C. These results suggest that BNKTYN-100 x NN ceramics are promising for energy storage equipment. • Using antiferroelectric NaNbO 3 to improve the energy storage performance of Bi 0.5 (Na 0.82 K 0.18) 0.5 TiO 3 -based ceramics. • A high W rec of 1.6 J/cm3 and η of 73.1 % at a lower electric field of 110 kV/cm were obtained in the x = 0.09 composition. • BNKTYN-9NN ceramics has outstanding dielectric temperature stability from 53 °C to 447 °C. [ABSTRACT FROM AUTHOR]

Lead-free (1- x)[(Bi 0.5 Na 0.5) 0.94 Ba 0.06 TiO 3 ]- x AgNbO 3 (abbreviated as BNTBT-100 x AN) ceramics were fabricated using a conventional solid-phase reaction technique. The effect of the antiferroelectric AgNbO 3 dopants for fatigue resistance, energy-storage density, temperature-stable permittivity, and conductivity mechanism was systematically investigated. The addition of AgNbO 3 led to the decrease of remnant polarization and the increase of dielectric breakdown strength, a large effective energy-storage density of ~1.27 J/cm3 corresponding to the conversion efficiency of ~ 77.5% for BNTBT-5AN ceramic were attained under applied 105 kV/cm field. Meanwhile, it exhibited an outstanding fatigue-resistant performance at 70 kV/cm fixed field up to 105 cycles accompanied with excellent temperature-stable properties in the temperature range of 30 °C ~ 120 °C. Besides, BNTBT-5AN sample has also obtained outstanding temperature-stable permittivity, which was associated with the enhancement of the ergodic relaxor domain structure. A little variance of dielectric content (Δ ε' / ε' 150 °C ≤ ± 15%) was acquired from 40 °C to 387 °C with a small tangent loss (tan δ ≤ 0.05) between 50 °C and 461 °C. Hence, it revealed that the high energy storage properties and excellent dielectric temperature stability for BNTBT-5AN ceramic were conducive to its better applications in electronic equipment. • A large effective energy-storage density of ~ 1.27 J/cm3 corresponding to the conversion efficiency of ~ 77.5% for x = 0.05 composition were attained under applied 105 kV/cm field. • BNTBT-5AN ceramic has also obtained outstanding temperature-stable permittivity, which was associated with the enhancement of the ergodic relaxor domain structure. • A little variance of dielectric content (Δ ε' / ε' 150 °C ≤ ± 15%) was acquired from 40 to 387 °C with a small tangent less (tan δ ≤ 0.05) between 50 °C and 461 °C for BNTBT-5AN ceramic. [ABSTRACT FROM AUTHOR]

The 0.94Bi 0.5 Na 0.5 TiO 3 –0.06BaTiO 3 (BNBT6) introduced by CaZrO 3 (CZ) lead-free ferroelectric ceramics are successfully fabricated by conventional solid state reaction. The influence of CZ substitution on the phase transition, microstructure, dielectric, ferroelectric, and energy storage properties of (1 − x)BNBT6-xCZ ceramics are systematically investigated. The energy-storage density 0.7 J/cm 3 under the electric field 70 kV/cm is obtained in the 0.97BNBT6-0.03CZ. In addition, its energy-storage property exhibits thermal stability at the temperature range of 30–130 °C. [ABSTRACT FROM AUTHOR]

Large electrocaloric effect is observed in La doped (Bi 0.5 Na 0.5 ) 0.94 Ba 0.06 TiO 3 lead-free ferroelectric ceramics synthesized by conventional solid state reaction. The dielectric permittivity and ferroelectric hysteresis loops are measured. The indirect method is used to calculate electrocaloric temperature change of BNBT6 doped by La. The introduction of La 2 O 3 can enhance the electrocaloric effect of BNBT6. The largest temperature change |Δ T 62 | = 2.61 K and electrocaloric coefficient | ξ max | = 0.052 Kcm/kV is achieved in the 0.5 wt% La doped BNBT6, which is significantly higher than that of BNT-based and lead-containing ferroelectric materials reported so far. For 1 wt% ones, the |Δ T 30 | = 1.954K and | ξ max | = 0.039 Kcm/kV is obtained in the room-temperature, which promises the environmental-friendly La doped BNBT6 is candidate for applications of solid state cooling devices. [ABSTRACT FROM AUTHOR]

• The doping of Li+ ion has an obvious influence on the strain and energy storage performance. • The TEM image and XPS spectra of O 1s for BNKTT-100xLi ceramics demonstrate the existence of PNRs and oxygen vacancies. • The maximum bipolar strain (S = 0.462%) and unipolar strain (S u = 0.443%) for x = 0.025 sample were obtained under 80 kV/cm, and its unipolar strain achieved 0.573% at 100 °C. • BNKTT-15Li ceramic exhibited outstanding energy storage performance with a recoverable energy density of 1.29 J/cm3 under applied 130 kV/cm field. The conventional solid reaction was used to synthesize (Na 0.8- x K 0.2 Li x) 0.5 Bi 0.5 Ti 0.985 Ta 0.015 O 3 (abbreviated as BNKTT-100 x Li) lead-free perovskite ceramics. The influences of Li+ ion doping for the relaxation mechanism and piezoelectric performances of all ceramics were systematically investigated. All ceramics exhibited a single perovskite structure, accompanied with a dense surface morphology and uniform element distributions. AC impedance spectroscopy showed the single grain conduction mechanism for all samples. The maximum bipolar strain (S = 0.462%) and unipolar strain (S u = 0.443%) for x = 0.025 sample were obtained under 80 kV/cm, and its unipolar strain achieved 0.573% at 100 °C. BNKTT-15Li ceramic exhibited outstanding energy storage performance with a recoverable energy density of 1.29 J/cm3 under applied 130 kV/cm field. It suggested that the excellent electro-strain and energy-storage properties for BNKTT-100 x Li ceramics could be widely applicable to electronic equipment. [ABSTRACT FROM AUTHOR]