(Pb0.8Ba0.2)[(Zn1/3Nb2/3)0.7Ti0.3]O₃ relaxor-type ferroelectric ceramics was obtained via classical solid-state reaction. The hysteresis loop results were discussed in the frame of ergodicity criterium around the characteristic ferroelectric relaxor freezing temperature. Slimer hysteresis loops were observed below the freezing temperature reflecting an ergodic relaxor behavior. Above this temperature, estimated around 223K for the studied system, larger and unsaturated like ferroelectric hysteresis loops were observed. This temperature also coincides with the slope change on maximum polarization and inflection point of remnant polarization curves. Energy storage, energy loss and efficiency values were determined in a wide temperature range. While the recoverable energy density shows relatively low values (0.23J/cm³), there are interesting behaviors for this parameter and for the efficiency, since the two physical quantities increase versus temperature and the efficiency even reaches the value of 97%.

Ferroelectric nanocapacitors have attracted intensive research interest due to their novel functionalities and potential application in nanodevices. However, due to the lack of knowledge of domain evolution in isolated nanocapacitors, precise manipulation of topological domain switching in the nanocapacitor is still a challenge. Here, we report unique bubble and cylindrical domains in the well-ordered BiFeO₃ nanocapacitor array. The transformation of bubble, cylindrical and mono domains in isolated ferroelectric nanocapacitor has been demonstrated via scanning probe microscopy (SPM). The bubble domain can be erased to mono domain or written to cylindrical domain and mono domain by positive and negative voltage, respectively. Additionally, the domain evolution rules, which are mainly affected by the depolarization field, have been observed in the nanocapacitors with different domain structures. This work will be helpful in understanding the domain evolution in ferroelectric nanocapacitors and providing guidance on the manipulation of nanoscale topological domains.

近年来，高功率、高能量密度的电容器成为新的研究热点，其在脉冲功率系统小型化和轻量化的发展中具有重要意义。本工作以BaTiO3-Bi(Mg0.5Zr0.25Ti0.25)O3固溶体为研究对象，致力于提高BaTiO3基陶瓷材料的储能密度，系统探究了不同含量的Bi(Mg0.5Zr0.25Ti0.25)O3对BaTiO3基陶瓷材料微观结构以及介电、铁电和储能性能的影响。采用标准固相烧结法制备出致密的(1-x)BaTiO3-xBi(Mg0.5Zr0.25Ti0.25)O3 (x=0.03、0.06、0.1、0.3、0.4)陶瓷。通过调整预烧及烧结条件，获得了陶瓷的最佳烧结工艺。随着x的增大，(1-x)BaTiO3-xBi(Mg0.5Zr0.25Ti0.25)O3陶瓷的室温晶体结构由四方相转变为立方相，同时材料从正常铁电体逐渐转变为弛豫型铁电体，介电常数峰值展宽，并在室温至500 ℃的温度范围内基本保持稳定。采用修正的Curie-Weiss定律和Vogel-Fulcher关系对陶瓷介电弛豫行为进行了深入分析。在极化特性方面，Bi(Mg0.5Zr0.25Ti0.25)O3成分的加入能够显著降低剩余极化强度(Pr)，增大介电强度，使电滞回线变细长，并使电滞回线中电场对极化的积分面积变大，从而使材料的储能密度得到提高。材料的最大储能密度大致呈先升高后降低的趋势，储能效率从75.08%提高到92.35%，并且在x=0.1时获得了最高的储能密度0.8 J/cm3 (储能效率为88.97%)。

One of the key points in the physics of the relaxors is their response to the applied DC field. Many studies of this topic were made, in particular on the influence of the field on the dielectric properties. However, practically, in all the cases, the measurements were performed at a fixed frequency and usually with the change in the temperature at the fixed field strength. In this paper, we report the evolution of the dielectric spectra at low frequencies (0.1 Hz <ω< 1 kHz) at fixed temperature 246 K on changing the DC electric field applied in (111) from 1 kV to 7 kV. Cole-Cole function was used to describe the spectra and the field dependences of the mean relaxation time τ, the oscillation strength Δ𝜀 and the width parameter α were determined. The obtained τ(E) and Δ𝜀(E) provide evidence of the field-induced transition from the nonpolar glass-like phase to the nonpolar paraelectric phase at around 1.5 kV/cm. In the paraelectric phase, very fast hardening of the spectra was observed with τ changing from 10 s to about 10−4s. The performed analysis demonstrated that the earlier reported positive C-V effect is completely determined by the spectra hardening, while Δ𝜀 does not show any change in the glass-like phase and monotonously decreases with a field increase in the paraelectric state. For complete understanding of the microscopic origin of the observed phenomena, a detailed study on the short-and long-range structures at the same condition is necessary.

Dielectric capacitors with high capacitive energy storage are urgently needed to meet the growing demand for high-performance energy storage devices. Herein, a novel lead-free Sr₅BiTi₃Nb₇O30 (SBTN) tungsten bronze relaxor ferroelectric ceramic is prepared and explored for potential energy storage applications. A high recoverable energy densityWrec (∼ 3.72 J/cm³) and ultrahigh efficiencyη (∼ 94.2%) at 380 kV/cm are achieved simultaneously. BothWrec andη exhibit superior stabilities against temperature (30–140∘C), cycles (10⁰ –10⁵) and frequency (1–500 Hz). In addition, a high current density of 796 A/cm² and a large power density of 71.7 MW/cm³ are achieved, together with good thermal endurance and fatigue resistance. These results demonstrate that the obtained SBTN ceramic can be deemed as the promising candidates for dielectric capacitor applications.Dielectric capacitors with high capacitive energy storage are urgently needed to meet the growing demand for high-performance energy storage devices. Herein, a novel lead-free Sr₅BiTi₃Nb₇O30 (SBTN) tungsten bronze relaxor ferroelectric ceramic is prepared and explored for potential energy storage applications. A high recoverable energy densityWrec (∼ 3.72 J/cm³) and ultrahigh efficiencyη (∼ 94.2%) at 380 kV/cm are achieved simultaneously. BothWrec andη exhibit superior stabilities against temperature (30–140∘C), cycles (10⁰ –10⁵) and frequency (1–500 Hz). In addition, a high current density of 796 A/cm² and a large power density of 71.7 MW/cm³ are achieved, together with good thermal endurance and fatigue resistance. These results demonstrate that the obtained SBTN ceramic can be deemed as the promising candidates for dielectric capacitor applications.

This work promotes the room temperature energy storage properties of the multiferroics. In this approach, impacts of PrFeO₃ doping on PT-based solid solutions (Pb1−xPrxTi1−xFexO₃, x = 0.21, 0.22, 0.23, 0.24, 0.25 and 0.26) have been explored. X-ray diffraction (XRD) patterns were used to estimate the crystallographic parameters, confirming the single phase tetragonal structure. The ferroelectric Curie temperature (TcFE) is observed to drop from 410 K to below room temperature as the Pr concentration increases. The ferroelectric P-E loops were used to determine the energy storage values at room temperature. The sample x = 0.24 achieved the maximum value of energy storage density of 362.25 mJ/cm³ with the efficiency of 40.5%. The ferroelectric P-E loops were used to determine the energy storage values at room temperature. The validity of magnetoelectric coupling in all samples was confirmed by magneto-dielectric studies and found that the sample x = 0.24 shows the maximum response with the coupling coefficient (γ) = 15.54 g²/emu².This work promotes the room temperature energy storage properties of the multiferroics. In this approach, impacts of PrFeO₃ doping on PT-based solid solutions (Pb1−xPrxTi1−xFexO₃, x = 0.21, 0.22, 0.23, 0.24, 0.25 and 0.26) have been explored. X-ray diffraction (XRD) patterns were used to estimate the crystallographic parameters, confirming the single phase tetragonal structure. The ferroelectric Curie temperature (TcFE) is observed to drop from 410 K to below room temperature as the Pr concentration increases. The ferroelectric P-E loops were used to determine the energy storage values at room temperature. The sample x = 0.24 achieved the maximum value of energy storage density of 362.25 mJ/cm³ with the efficiency of 40.5%. The ferroelectric P-E loops were used to determine the energy storage values at room temperature. The validity of magnetoelectric coupling in all samples was confirmed by magneto-dielectric studies and found that the sample x = 0.24 shows the maximum response with the coupling coefficient (γ) = 15.54 g²/emu².

This work harmonizes the experimental and theoretical study of electrocaloric effect (ECE) in (Pb0.8Bi0.2)(Zr0.52Ti0.48)O₃ solid solution by optimizing sintering temperature. Bi3+-doped PbZr0.52Ti0.48O₃ solid solutions were synthesized by the conventional solid-state reaction method. Different samples were prepared by varying the sintering temperature. X-ray diffraction study confirms the crystalline nature of all the samples. An immense value of polarization has been acquired in the optimized sample. The maximum adiabatic temperature change of order 2.53 K with electrocaloric strength of 1.26 K mm kV−1 has been achieved experimentally. Whereas a comparatively close value of ECE has been acquired from the theoretical calculations using a phenomenological approach. Furthermore, a large value (218 mJ cm−3) of thermal energy conversion has been obtained using the Olsen cycle.This work harmonizes the experimental and theoretical study of electrocaloric effect (ECE) in (Pb0.8Bi0.2)(Zr0.52Ti0.48)O₃ solid solution by optimizing sintering temperature. Bi3+-doped PbZr0.52Ti0.48O₃ solid solutions were synthesized by the conventional solid-state reaction method. Different samples were prepared by varying the sintering temperature. X-ray diffraction study confirms the crystalline nature of all the samples. An immense value of polarization has been acquired in the optimized sample. The maximum adiabatic temperature change of order 2.53 K with electrocaloric strength of 1.26 K mm kV−1 has been achieved experimentally. Whereas a comparatively close value of ECE has been acquired from the theoretical calculations using a phenomenological approach. Furthermore, a large value (218 mJ cm−3) of thermal energy conversion has been obtained using the Olsen cycle.

This paper reports the impact of the laser pulse repetition frequency on growth processes, morphological and electro-physical parameters of nanocrystalline LiNbO₃ thin films obtained by the pulsed laser deposition technique. It was found that the nucleation process in LiNbO₃ films could controllably change by increasing the laser pulse repetition frequency. The film obtained at the repetition frequency of 4 Hz consists of local islands and clusters with a diameter of 118.1 ± 5.9 nm. Nanocrystalline films, grown at the repetition frequency of 10 Hz, possess a continuous granular structure with a grain diameter of 235 ± 11.75 nm. Achieved results can be used for the development of promising “green” energy devices based on lead-free piezoelectric energy harvesters.This paper reports the impact of the laser pulse repetition frequency on growth processes, morphological and electro-physical parameters of nanocrystalline LiNbO₃ thin films obtained by the pulsed laser deposition technique. It was found that the nucleation process in LiNbO₃ films could controllably change by increasing the laser pulse repetition frequency. The film obtained at the repetition frequency of 4 Hz consists of local islands and clusters with a diameter of 118.1 ± 5.9 nm. Nanocrystalline films, grown at the repetition frequency of 10 Hz, possess a continuous granular structure with a grain diameter of 235 ± 11.75 nm. Achieved results can be used for the development of promising “green” energy devices based on lead-free piezoelectric energy harvesters.

采用铌铁矿前驱体两步法制备了Pb(Zn1/3Nb2/3)0.2(Hf1-xTix)0.8O3(PZNH1-xTx)钙钛矿压电陶瓷, 研究了铪钛比对陶瓷相结构、电学性能和能量收集特性的影响。结果表明, 当x=0.52时, 陶瓷样品位于准同型相界, 具有最优综合压电性能: 居里温度TC=287 ℃, 品质因数FOM≈14 753×10-15 m2/N, 压电电荷常数d33=492 pC/N。由该组成材料构建的悬臂梁型压电能量收集器输出功率密度高达4.16 μW/mm3, 所转化的电能可成功点亮138盏并联的LED灯。结果表明, PZNHT陶瓷在压电能量收集领域具有良好的应用潜力。