High piezoelectricity of BaTiO3–CaTiO3–BaSnO3 lead-free ceramics
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 EC = 1.31 kV cm−1 and higher Pr = 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.