A Research on Delayed Thermal Depolarization, Electric Properties, and Stress in (Bi0.5Na0.5)TiO3-Based Ceramic Composites

Xingru Zhang; Yinan Xiao; Chao Yang; Yuandong Wu; Min Wen; Junke Jiao; Rui Li; Liyuan Sheng; Wenchang Tan

doi:10.3390/ma15093180

A Research on Delayed Thermal Depolarization, Electric Properties, and Stress in (Bi_0.5Na_0.5)TiO₃-Based Ceramic Composites

Materials (Basel). 2022 Apr 28;15(9):3180. doi: 10.3390/ma15093180.

Authors

Xingru Zhang^{1

2}, Yinan Xiao^{1

2}, Chao Yang³, Yuandong Wu^{1

2}, Min Wen^{1

2}, Junke Jiao⁴, Rui Li², Liyuan Sheng^{1

2}, Wenchang Tan^{1

2}

Affiliations

¹ Shenzhen Institute, Peking University, Shenzhen 518057, China.
² PKU-HKUST ShenZhen-HongKong Institution, Shenzhen 518057, China.
³ Key Laboratory for Photonic and Electronic Bandgap Materials Ministry of Education, School of Physics and Electronic Engineering, Harbin Normal University, Harbin 150025, China.
⁴ School of Mechanical Engineering, Yangzhou University, Yangzhou 225127, China.

Abstract

Depolarization behavior is one of the main shortcomings of (Bi_0.5Na_0.5)TiO₃-based ceramics. Considering the undesirable efficiency of traditional modification methods, in this paper a series of 0-3 type ceramic composites 0.85(Bi_0.5Na_0.5)TiO₃-0.11(Bi_0.5K_0.5)TiO₃-0.04BaTiO₃-x mol% ZnO (BNKT-BT-xZnO)) were synthesized by introducing ZnO nanoparticles. The results of the X-ray diffraction pattern (XRD) and energy dispersive spectroscopy (EDS) demonstrate that the majority of ZnO nanoparticles grow together to form enrichment regions, and the other Zn²⁺ ions diffuse into the matrix after sintering. With ZnO incorporated, the ferroelectric-ergodic relaxor transition temperature, T_F-R, and depolarization temperature, T_d, increase to above 120 °C and 110 °C, respectively. The research on temperature-dependent P-E loops verifies an attenuated ergodic degree induced by ZnO incorporation. For this reason, piezoelectric properties can be well-maintained below 110 °C. The electron backscatter diffraction (EBSD) was employed to investigate the stress effect. Orientation maps reveal the random orientation of all grains, excluding the impact of texture on depolarization. The local misorientation image shows that more pronounced strain appears near the boundaries, implying stress is more concentrated there. This phenomenon supports the hypothesis that potential stress suppresses depolarization. These results demonstrate that the depolarization behavior is significantly improved by the introduction of ZnO. The composites BNKT-BT-xZnO are promising candidates of lead-free ceramics for practical application in the future.

Keywords: BNT-based ceramic composite; ZnO incorporation; depolarization behavior; electric properties; stress.

Abstract

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