Phenomenological thermodynamic potentials for bulk and thin-film Ba(Zr_(0.08)Ti_(0.92))O_3 single crystals

摘要

Phenomenological thermodynamic analysis is an important theoretical investigation method for ferroelectric materials, however, it cannot be implemented for Ba(Zr_xTi_(1-x))O_3 due to the lack of thermodynamic potential coefficients. In this paper, we have constructed a phenomenological thermodynamic potential for bulk Ba(Zr_(0.08)Ti_(0.92))O_3 single crystals, which reproduces the three phase transition temperatures, dielectric and piezoelectric constants of bulk Ba(Zr_(0.08)Ti_(0.92))O_3 single crystals well, suggesting that the constructed thermodynamic potential is reliable. Then the thermodynamic potential with appropriate modification is applied to predict misfit strain-temperature phase diagram and electromechanical properties of Ba(Zr_(0.08)Ti_(0.92))O_3 thin films. It is found that compressive strain favors the tetragonal c phase with an out-of-plane polarization component, while tensile misfit strain favors orthorhombic aa phase with an in-plane polarization component. It also reveals that Ba(Zr_(0.08)Ti_(0.92))O_3 thin films under appropriate compressive strain show higher piezoelectric coefficient d_(15) than that of their bulk counterpart. The constructed thermodynamic potential opens a new avenue to theoretical analysis on Ba(Zr_(0.08)Ti_(0.92))O_3.