High piezoelectricity of BaTiO3–CaTiO3–BaSnO3 lead-free ceramics

Abstract

A series of solid solutions of BaTiO₃–x(0.4CaTiO₃–0.6BaSnO₃) (abbreviated as BT–x(CT–BS), x = 0.00–0.20 mol) were prepared to search for high performance lead-free piezoelectric ceramics. Through content tailoring, a complex phase transition was confirmed by X-ray diffraction and Raman spectra as well as temperature dependence of the dielectric constant, which occurs from tetragonal(T)–orthorhombic(O) coexistence at 0 ≤ x ≤ 0.12 to rhombohedral(R)–O–T and R–O/T–cubic(C) multiphase coexistence at x = 0.16 and 0.20, respectively. The lower E_C = 1.31 kV cm⁻¹ and higher P_r = 9.48 μm cm⁻² as well as high piezoelectric response d₃₃ = 570 pC N⁻¹ were achieved in BT–x(CT–BS) ceramics at an optimal composition of x = 0.16. The ultrahigh converse piezoelectric coefficient d^*₃₃ = 1444 pm V⁻¹ and strain = 0.070% which are the highest values reported so far in lead-free ceramics also were achieved at x = 0.16, suggesting that a BT–x(CT–BS) system is a promising lead-free alternative material for electromechanical actuator applications.