Phase coexistence and large piezoelectricity in BaTiO3‐CaSnO3 lead‐free ceramics

Ferroelectric phase coexistence was constructed in (1?x)BaTiO₃‐xCaSnO₃ lead‐free ceramics, and its relationship with the piezoelectricity of the materials was investigated to ascertain potential factors for strong piezoelectric response. It is found that the addition of CaSnO₃ caused a series of phase transitions in the (1?x)BaTiO₃‐xCaSnO₃ ceramics, and a ferroelectric coexistence of rhombohedral, orthorhombic, and tetragonal phases is formed at x = 0.08, where the ceramics exhibit the lowest energy barrier and consequently facilitate the polarization rotation and extension, resulting in the optimal piezoelectricity of d₃₃ and k_p values of 550 pC/N and 0.60, respectively. Our study provides an intuitive insight to understand the origin of high piezoelectricity in the ceramics with the coexistence of multiferroelectric phases.