Dielectric and piezoelectric properties of YMnO3 modified Bi0.5Na0.5TiO3 lead-free piezoelectric ceramics

Perovskite lead-free piezoelectric ceramics Bi0.5Na0.5TiO3, modified with yttrium and manganese to form a new compound, (1 − x) Bi0.5Na0.5TiO3–xYMnO3 (BNT-YM100x) with x = 0–1.2 mol%, was synthesized by a conventional solid-state reaction method. The effect of YMnO3 on crystal structure, dielectric and piezoelectric properties was investigated. X-ray diffraction analysis shows that the materials have a single phase perovskite structure with rhombohedral symmetry. Addition of small amount of YMnO3 improves piezoelectric properties and the optimal piezoelectric properties of d33 = 115 pC/N, kp = 0.207 and Qm = 260 were obtained at 0.9% YMnO3 addition. The loss tangent tanδ is approximately constant while Curie temperature decreases with increasing YMnO3 concentration.