多孔PZT95/5铁电陶瓷的机械性能和铁电性能研究

采用添加造孔剂的方法制备多孔锆钛酸铅(PZT95/5)铁电陶瓷, 研究了孔结构包括孔隙率、孔径及孔形状对多孔PZT95/5陶瓷机械性能和电性能的影响及机理, 并揭示多孔PZT95/5陶瓷微观结构、机械性能和铁电性能的内在联系。研究表明: 孔隙率的增加降低了多孔PZT95/5陶瓷的声阻抗, 改善了陶瓷与封装材料的声阻抗匹配. 孔隙率增加, 多孔PZT95/5陶瓷的屈服应力和剩余极化强度降低, 矫顽场强增大。孔结构对多孔PZT95/5陶瓷屈服应力的影响可由应力集中理论解释; 多孔PZT95/5陶瓷剩余极化强度随孔结构的变化可用内应力结合空间电荷理论加以解释。

Investigation on the Mechanical and Ferroelectric Properties of the Porous PZT 95/5 Ceramics

Porous lead zirconate titanate (PZT95/5) ceramics were prepared by adding pore formers. The effects of pore structures including porosity, pore size and pore shape on the mechanical and ferroelectric properties of the porous PZT95/5 ceramics and their mechanisms were investigated, and the relationships between the microstructures and the mechanical and ferroelectric properties were revealed. The results showed that increase in porosity improved the acoustic impedance matching between ceramics and encapsulating materials by reducing the sound impedance values. With increase in porosity, the yield stress and remnant polarization (P_r) of the porous PZT95/5 ceramics decreased, while the coercive electric field increased. The porous PZT95/5 ceramics with spherical pores exhibited higher yield stress and remnant polarization (P_r) than that with irregular pores. The porous PZT95/5 ceramics with larger pore size exhibited lower yield stress and remnant polarization. However, compared with pore shape, pore size had minor effects on the yield stress and remnant polarization properties of the porous PZT95/5 ceramics. The effect of pore structure on the yield stress could be explained by stress concentration theory. The microscopic internal stress combined with space-charge theory was used to explain the variation of the remnant polarization with the pore structure.