Inhomogenous Amorphous Content and Enhanced Piezoelectric Properties in Bi12TiO20-based Composite Ceramics

Abstract

Bi12TiO20-based composite ceramics were prepared by sintering a mixture of presynthesized Bi12TiO20 and a second phase around the melting point of Bi12TiO20. These ceramics can exhibit direct as well as inverse piezoelectricity without electrical polarization, and become competitive piezoelectric material with high depoling temperature and stable thermal behavior. However, their piezoelectric constants were, in general, relatively low and do not remain consistent for both the symbol and magnitude over the entire surface. To prevent the permeation of melting Bi12TiO20 into substrate and thus create the inhomogenous amorphous content, samples were sintered on Al2O3 (0001) single crystal substrate. Compared to samples sintered on Al2O3 ceramics, piezoelectric coefficient (d33) of these samples was increased by 80%. Moreover, the symbol of d33 is identical on the whole surface. Here, the enhanced piezoelectricity might be ascribed to increased alignment of distorted BiO5 polyhedra in amorphous Bi12TiO20 phase. These results provided a method to improve the piezoelectric properties of Bi12TiO20-based ceramics and provided some inspiration for further development of Bi12TiO20-based ceramics suitable for practical applications.