Phase transitions and phase diagram of Ba(Zr_0.2Ti_0.8)O₃-x(Ba_0.7Ca_0.3)TiO₃ Pb-free system by anelastic measurement

The internal friction and storage modulus of Ba(Zr_0.2Ti_0.8)O₃-x(Ba_0.7Ca_0.3)TiO₃ (BZT-xBCT) Pb-free ceramics have been measured by dynamic mechanical analysis. The anelastic properties show clear anomalies with regard to the transformations between cubic (C), tetragonal (T), orthorhombic (O), and rhombohedral (R) phases, which are all of ferroelastic in nature. The previous reported T-R transition region in the BZT-xBCT system can be divided into the T-O and O-R transitions, consistent with recent studies on the appearance of an intermediate O phase. Based on the internal friction and storage modulus results, a revisited version of BZT-xBCT phase diagram is proposed.