Abstract
Crystal structure and piezoelectric property of the system Pb(Zn1/3Nb2/3)O3-PbTiO3 were studied with single crystals and ceramic polycrystals. A PbO-flux method was used for growing the single crystals. Pure Pb(Zn1/3Nb2/3)O3 single crystal has perovskite structure of rhombohedral system. The crystal structure changes to tetragonal when dissolved PbTiO3 exceeds 10 mol %. Piezoelectric activity increases remarkably in the composition range where the phase change is observed i.e., the electromechanical coupling factor k33 amounts to 75% and the dielectric constant ε33 is 4200. These tendencies are similar to those in the solid solution PbZrO3-PbTiO3.
Pb(Zn1/3Nb2/3)O3 ceramic polycrystal has a pyrochlore structure and shows undetectable piezoelectricity. A compound of perovskite structure and that of pyrochlore structure coexist in specimens containing less than 40 mol% PbTiO3. The coexistence gives rise to extremely low piezoelectric activity.
