We explain how the phenomena of ferroelectric phase transition temperature Tc enhancement beyond the end members in perovskite solid solution such as BiMO3-PbTiO3 (M = Sc, In, etc.) is related to nonlinear and spatial correlation effects. The explanation is based on the calculation of Tc in the framework of our random field theory with additional account for nonlinear effects in the above substances. We show that the maximum of Tc for certain PbTiO3 content takes place when coefficient of nonlinearity is positive, the value of this coefficient is found from best fit between theory and experiment. This nonlinearity coefficient is the only adjustable parameter of the theory. We show that enhancement of positive nonlinearity coefficients enhances greatly the Tc maximum over its value for end members. The theory lays the foundation to calculate not only Tc for above solid solutions but virtually any equilibrium and/or nonequilibrium thermodynamic characteristics such as static and dynamic dielectric susceptibility, specific heat, etc., as a function of PbTiO 3 content, temperature, electric field, and other external parameters.
|Original language||English (US)|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - Oct 2004|
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics