该文采用传统固相合成法制备了Bi0.5Na0.5Ti(1-x)HfxO3 (x=0, 0.02, 0.04和0.06)陶瓷, 通过X线衍射仪(XRD)和扫描电子显微镜(SEM)表征了其相结构、微观表面, 并研究了其介电性能、铁电性能及比热容与相变的关系。通过构建电场和温度的条件, 共同调控铁电相变。再借助麦克斯韦方程, 通过间接法计算, 最终在50 ℃、70 kV/cm的电场下, 在Bi0.5Na0.5TiO3-0.04Hf陶瓷中通过诱导畴变得到了0.5 K的负电卡效应。

i0.5Na0.5Ti(1-x)HfxO3 (x=0, 0.02, 0.04, 0.06) ceramics were made using the conventional solid-state synthesis method in this study. By using XRD and SEM to characterize the phase structure and microsurface, the dielectric and ferroelectric characteristics, but also the connection between specific heat capacity and phase transition, were all investigated. In the study, we regulate the temperature and electric field to control the ferroelectric phase transition. The electrocaloric effect to be close to room temperature is excepted. Finally, the negative electrocaloric effect of ΔT=0.5 K was successfully attained in Bi0.5Na0.5TiO3-0.04Hf ceramics by induced domain switching at 50 ℃ and 70 kV/cm electric field with the aid of Maxwell’s equation and the indirect method.