BSZT thin films Bridgman technique Maxwell relation NBT epitaxial film P-E hysteresis loop PMN-32PT PMN-32PT single crystal PMN-PT RF magnetron sputtering Research & information: general acceptor doping capacitance properties ceramic characterization charged defects dielectric relaxation electrical conduction electrocaloric effect ferroelectric materials ferroelectric properties lead-free piezoelectric segregation single crystals ultraviolet light