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Piezoelectric ceramics with excellent piezoelectric properties and a high Curie temperature are important for numerous electromechanical devices in a broad range of temperature environments. In this work, the relaxor ferroelectric Pb(Yb1/2Nb1/2)O3 end member was selected to be introduced into a BiScO3-PbTiO3 high-temperature piezoelectric ceramic to reduce the dielectric loss and improve the piezoelectric properties while slightly reducing the Curie temperature. The phase structure and dielectric, ferroelectric and piezoelectric properties of 0.025Pb(Yb1/2Nb1/2)O3-(0.975−x)BiScO3-xPbTiO3 (0.60 ≤ x ≤ 0.63) ceramics were systematically analyzed, and the best electrical properties were observed in the morphotropic phase boundary region x = 0.61 with d33 = 370 pC/N, kp = 44%, Pr = 33.9 μC/cm2. Importantly, no significant depolarization was observed in the x = 0.61 ceramic from room temperature to 290 °C, demonstrating its good thermal stability and potential applications in a wide range of temperature environments.

Class II ceramics are a material with high permittivity but low reliability of their capacitance and bias voltage due to high the temperature sensitivity of their dielectric permittivity. In this work, a BST-based (Ba0.9−xSrxCa0.1)TiO3·0.03(Bi2O3·3TiO2) (x = 0.2, 0.25, 0.3, 0.35, 0.4) composition with Y5U characteristics was investigated through compositional control to develop high-permittivity and voltage-stable ceramic compositions. Sr doping can increase the breakdown strength (Eb) but decreases the Curie temperature (Tc). The composition at x = 0.3 can obtain optimal comprehensive electrical properties, with high permittivity of 4206, low dielectric loss of ~0.009, and moderate breakdown strength (Eb) of 77.6 kV/cm, which meets Y5U specifications. Typically, a low bias-voltage dependence of capacitance is confirmed with a variation rate of 7.64% under 20 kV/cm. This strategy provides a promising candidate for high-permittivity Class II ceramic dielectrics that can be used in this field.

For dielectric energy storage materials, high polarization and high breakdown strengths are a long-standing challenge. A modulating crystalline/amorphous phase structure strategy is proposed by Mn-doping and annealing temperature to enhance the energy storage performance of pure BaTiO3 (BT) films. In this study, lead-free Mn-doped BT films were prepared on Pt/Ti/SiO2/Si substrates via the sol-gel method, and the effects of the crystalline/amorphous phase ratio on polarization and electric properties were analyzed. A small amount of Mn-doping in BT could reduce the annealing temperature and enhance polarization with an Mn content of 8%. In addition, the energy storage properties of BT-8%Mn films achieve the best energy storage performance in terms of energy density and efficiency of 72.4 J/cm3 and 88.5% by changing the annealing temperature to 640 °C. BT-8%Mn energy storage films also possess good stability over a wide temperature range of 20 °C–200 °C, which demonstrates that crystalline/amorphous engineering is a simple and effective way to enhance energy storage applications of dielectric films.

The preparation of low-cost multilayer piezoelectric devices requires using cheap internal electrodes between the dielectric layers. A general strategy is to reduce the sintering temperature Ts of the ceramic layer by sintering aids which can form a liquid phase. Here, 0.2 wt% Li2CO3 was added as a sintering aid to tailor the sinterability and piezoelectricity of the commercial PZT ceramics. As verified from experiments, the piezoelectric ceramics could be densified at a sintering temperature above 940 °C, suitable for co-firing with the cheap internal electrode. The optimized sintering temperature of 980 °C can be confirmed for the 0.2 wt% Li2CO3-modified PZT ceramics due to its high piezoelectric coefficient d33 ~ 701 pC/N, planar coupling factor kp ~ 66.7%, and a low mechanical quality factor Qm ~ 71 with a transition temperature of Tc ~ 226 °C, presenting the characteristics of typical soft piezoelectric ceramics. Moreover, both the potential piezoelectric strain ~0.13% under 20 kV/cm and the good cycling fatigue characteristic (>104 cycles) of the studied piezo compositions indicates strong competitiveness in the field of multilayer piezoelectric devices.

Relaxor-type ferroelectrics show important potential in energy storage fields due to their significantly enhanced energy performance and good temperature stability compared to normal ferroelectrics. Here, a novel, high-performance ternary composition, (0.4−x)BiFeO3-xBi(Mg1/2Ti1/2)O3–0.6BaTiO3 (x = 0.2, 0.25, 0.3, 0.35, 0.4), was designed by compositional modulation, which displays typical relaxor characteristics. The optimum energy storage properties can be attained at x = 0.35, accompanied by energy efficiency of 84.87%, a promising energy storage density of 2.3 J/cm3 and good temperature stability of less than 10% over 20–160 °C. Moreover, the samples provide stable cycling fatigue after 105 cycles and a fast discharge time of t0.9 < 0.1 μs, indicative of promising applications in energy units.

Dielectric film capacitors are considered as potential candidates for advanced power electronics technology due to their extremely high-power densities and outstanding mechanical and thermal stability, but the further improvement of energy storage density is still needed. Here, a strategy is proposed to enhance the energy storage properties by introducing nanoscale polarization regions into amorphous films, which can significantly improve the maximum polarization and maintain a high breakdown strength. The (1−x) BaTiO3-xBi(Ni0.5Zr0.5)O3 ((1−x)BT-xBNZ) thin films are fabricated by the sol– gel method and the amorphous films with nanoscale polarization regions are obtained by adjusting the preparation process. Consistent with the conjecture, amorphous phase and nanoscale polarization regions in the (1−x) BT-xBNZ films are clearly observed by electron diffraction. Results show that giant recoverable energy density of 103.7 J cm−3 with high energy efficiency of 88.3% are simultaneously achieved at 8.3 MV cm−1 in 0.92BT-0.08BNZ thin films. Furthermore, the 0.92BT-0.08BNZ thin film exhibits excellent thermal stability in a wide temperature range of 20–200°C, ΔWrec/Wrec20°C < 2.2%. This work provides a novel method for dielectric thin film capacitors applied in high temperature and electric field. [ABSTRACT FROM AUTHOR]