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

A Ce 4+ -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 Ce 4+, the ferroelectric phase gradually transferred to the relaxor phase. The addition of an appropriate number of Ce 4+ ions led to a larger grain size of the BiFeO 3 –BaTiO 3 (BF–BT) ceramics, a lower Fe 2+ content, and higher resistivity. At a Ce 4+ concentration ( x ) of 0.3 mol %, the BF–BT– x Ce ceramic exhibited excellent dynamic piezoelectric coefficients ( d 33 * = 406 pm/V) and a high Curie temperature of 418.2 °C. Furthermore, the d 33 * (406 pm/V) at room temperature of BF–BT–0.003Ce significantly increased to 759 pm/V at 125 °C. The enhanced field-induced strain performance of the ceramics is attributable to lattice distortion induced by Ce 4+ 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.