Dielectric, Ferroelectric, and High-Temperature Strain Behavior of Rare Earth Ce-Doped 0.67BiFeO₃-0.33BaTiO₃ Lead-Free Ferroelectric Ceramics

A Ce4+-substituted 0.67BiFeO(3)-0.33BaTiO(3) lead-free ceramic system was systematically investigated. The results indicate that all samples exhibit the coexistence of rhombohedral phase and pseudocubic phase. Dielectric measurements indicate that with the doping of Ce4+, the ferroelectric phase gradually transferred to the relaxor phase. The addition of an appropriate number of Ce4+ ions led to a larger grain size of the BiFeO3-BaTiO3 (BF-BT) ceramics, a lower Fe2+ content, and higher resistivity. At a Ce4+ concentration (x) of 0.3 mol %, the BF-BT-xCe ceramic exhibited excellent dynamic piezoelectric coefficients (d(33)* = 406 pm/V) and a high Curie temperature of 418.2 degrees C. Furthermore, the d(33)* (406 pm/V) at room temperature of BF-BT-0.003Ce significantly increased to 759 pm/V at 125 degrees C. The enhanced field-induced strain performance of the ceramics is attributable to lattice distortion induced by Ce4+ doping. The temperature-dependent behavior of the field-induced strain in the BF-BT-Ce ceramics was enhanced by thermally induced domain switching. This study confirms the potential of the investigated BF-BT-Ce ceramics as promising lead-free, environmentally friendly, and high-temperature piezoelectric material.