High piezoelectric response and polymorphic phase region in the lead-free piezoelectric BaTiO3-CaTiO3-BaSnO3 ternary system

Abstract

This study attempted to replace Pb-based piezoelectric ceramics with a non-toxic lead-free (Ba,Ca)(Ti,Sn)O3 substitute, according to current environmental standards. The design of the (Ba(0.825+x)Ca(0.175-x))(Ti(1-x)Snx)O3 lead-free piezoceramics reported herein was based on chemical modifications by varying Sn concentrations (x = 0.0500-0.1250). The effect of Sn ion modifications on structural evolution and dielectric, ferroelectric and piezoelectric properties was investigated. Partial substitution of Ti with Sn yields a suitable composition with multiphase boundaries near room temperature. As a result, the composition, x = 0.1000, shows outstanding piezoelectric values of d33 = 515 pC N-1 and = 1293 pm V-1 at 10 kV, which are higher than those found in commercially available soft PZT. Furthermore, anomalous dielectric relaxation is far below the rhombohedral to orthorhombic phase transition at T ≈ 90-150 K, and was found clearly in all compositions. The relaxation fitted the Vogel-Fulcher model with an activation energy of Ea ≈ 20-70 meV and freezing temperature of TVF ≈ 65-85 K.