Processing and Application of Ceramics (Dec 2007)
Tunability modelling and experiments for BaTiO3-based solid solutions
Abstract
In this paper, the electric field dependence of the dielectric constant in some BaTiO3-based ferroelectrics is theoretically described by means of the Landau-Ginzburg-Devonshire (LGD) theory and its’ approximations valid for low polarizations (Johnson’s equation and even-power relation) when the sample is in its ferroelectric state and by a model considering random non-interacting dipolar units in a double well potential for the paraelectric state. High-voltage tunability data were obtained at room temperature for BaZr0.10Ti0.90O3 and Ba0.70Sr0.30TiO3 ceramics. The data were well fitted by using the Johnson’s approximation for the ferroelectric-relaxor BaZr0.10Ti0.90O3 and satisfactory for the Ba0.70Sr0.30TiO3 ceramics, close to its ferro-para phase transition. For the last one, the non-interacting dipolar units model allows to determine the average dipolar moment.
