Phase boundary and electric field induced polarization rotation in lead-free Ba(Zr0.2Ti0.8)O3-(Ba0.7Ca0.3)TiO3

Ba(Zr0.2Ti0.8)O3-x(Ba0.7Ca0.3)TiO3 (BZT-xBCT) is a promising lead-free ferroelectric system with high piezoelectricity. Here we carry out phenomenological calculations to explore phase stability and electric field induced phase transition. Study of free energy variation near phase boundaries revealed ultralow energy barrier in single orthorhombic phase region and phase coexistence around inter-ferroelectric transitions. The calculated critical electric field for tetragonal-orthorhombic transition is in reasonable agreement with experimental data. Temperature–composition phase diagram under [001], [011] and [111] oriented electric field are computed, and polarization rotation associated monoclinic structures are studied.