Curie-Weiss law of (Ba_1-xSr_x)TiO₃ thin films prepared by chemical solution deposition

Abstract
The paper presents a study of the temperature dependence of the relative permittivity of (Ba_1-xSr_x)TiO₃, x = 0...l, thin films grown by a chemical solution deposition (CSD) method on platinum coated silicon substrates. Glancing incidence X-ray diffraction analysis revealed a cubic or pseudocubic perovskite lattice for al1 films under investigation. The morphology of the polycrystalline BST thin films was varied between a fine grained and a columnar microstructure by adjusting the concentration of the spin-on solution. The thin film microstructure was studied on cross section samples by means of scanning electron microscopy. The temperature dependence of the relative permittivity of the whole series of BST thin films was measured by impedance analysis at 10 kHz in the temperature range from - 200 °C to 400 °C. The constants (C and T_c) of the Curie-Weiss Law were determined for the thin films and compared to the values of bulk ceramics in the light of the mixing rule theory for a two component system.