Thermodynamic analysis of temperature-graded ferroelectrics

A Landau–Ginzburg thermodynamic model is constructed and used to develop a methodology for analyzing temperature-graded ferroelectrics. Spatial nonuniformities in temperature are shown to give rise to nonuniformities in polarization with corresponding spatial variations. The magnitude and the sign of the polarization gradients are shown to depend on the imposed temperature gradient. The polarization gradients result in asymmetric hysteresis responses with “up” or “down” charge offsets. The theoretical analysis presented here not only predicts the general trends associated with the hysteresis offsets observed from temperature-graded ferroelectrics, but is also in excellent quantitative agreement with the experimental data reported in the literature [W. Fellberg, J. V. Mantese, N. W. Schubring, and A. L. Micheli, Appl. Phys. Lett. 78, 524 (2001)].