Dielectric Properties of Pb(Zr, Ti)O3-Dispersed MgO Nanocomposite

Abstract

Ceramic nanocomposites with perovskite-type ferroelectric dispersoids have been studied in order to introduce ferroelectricity and piezoelectricity into structural ceramics. First, MgO matrix/BaTiO₃ dispersed ceramic nanocomposites were fabricated, but the piezoelectric coupling factor, k _p, of the nanocomposites was reduced to less than 5%. In the present work, MgO matrix/Pb(Zr,Ti)O₃ (PZT) dispersed ceramic nanocomposites were studied to realize ceramic nanocomposites with larger k _p values than MgO/BaTiO₃. MgO/PZT ceramic nanocomposites were successfully fabricated by a pressure-less sintering method. The MgO/PZT nanocomposites exhibited a D–E hysteresis loop, and the ferroelectricity of the PZT dispersoid was confirmed. The tetragonality of the PZT dispersoid was decreased in comparison to that of monolithic PZT ceramics, however, the tetragonal-cubic phase transformation temperature of the PZT dispersoid was higher than that of the monolithic PZT. The decrease in the tetragonality was correlated to the incorporation of Mg ions into the PZT dispersoid. The MgO/PZT nanocomposites exhibited piezoelectricity after poling, and the k _p value was about twice that of the MgO/BaTiO₃ nanocomposites.