Phase structure and piezoelectric properties of high Curie temperature BiYbO₃-PbTiO₃-BaTiO₃ ceramics

Perovskite (1 - x)(0.1BiYbO₃-0.9PbTiO₃)-xBaTiO₃ (BYPT-BT) ceramics were prepared by the conventional processing. The effect of BaTiO₃ on the microstructure and piezoelectric properties was investigated. The results show that the perovskite phase and the Yb₂Ti₂O₇ pyrochlore phase are coexisting in the BYPT-BT ceramics. BaTiO₃ influences the lattice structure and Ba²⁺ will replace A-site ions of perovskite, which decreases the lattice constant ratio c/a, leading to the lattice distortion. With increasing BaTiO₃ content, the percentage of pyrochlore phase decreases, which resulted in the increase of the dielectric constant ε and the piezoelectric constant d₃₃. BYPT-BT ceramics with the high Curie temperatures of > 500 °C are obtained. And BYPT-BT₄ ceramics with 0.12 mol BaTiO₃ has the optimal piezoelectric properties, ε is 720, tan δ is 0.013, d₃₃ is 34 pC/N, T_C is 505 °C.