Barium strontium titanate (Ba0.6Sr0.4TiO3, BST) films have been deposited on Pt/Ti/SiO2/Si substrates by radio frequency magnetron sputtering. The influences of conventional thermal annealing (CTA) and rapid thermal annealing (RTA) on the chemical structures of the surface layers of the BST films have been investigated. Grazing x-ray diffraction and atomic force microscopy show that the RTA-films exhibit more compact structure and more completed crystallization than the CTA-films. X-ray photoelectron spectroscopy (XPS) investigations show that the surface layer is composed of a non-perovskited BST phase and a perovskited BST phase. For the CTA-film, the surface contains about 70% non-perovskited BST phase, and the surface layer is approximately 3–5 nm thick, while for the RTA-film, the surface non-perovskited BST phase amounts to about 40%, and the surface layer is about 1nm. XPS also indicates that the CTA-film surface adsorbs a larger amount of carbon contaminations than the RTA-film. Fourier transform infrared reveals that the amount of the surface adsorbed water and/or OH groups may be ignored. The non-perovskited BST phase is mainly related to the surface structure and the adsorbed carbon contaminations. The effect of annealing temperature on the surface layer and the amount of non-perovskited BST phase has been discussed, and the dielectric properties have also been measured.

Structure‐property relationships of Y2MgTiO6, a type of double perovskite materials, were investigated systematically. Rietveld refinement of XRD patterns confirmed that Y2MgTiO6 belongs to the P21/c space group and has a structure analogous to that of monoclinic Dy2MgTiO6. In accordance with the observed number of vibrational bands and group theoretical predictions, O and Y ions at the 4e site dominated the Raman peaks. The IR reflectivity spectrum indicated that the major contributions to the relative permittivity and intrinsic loss were modes lower than 500 cm−1. The measured relative permittivity closely approached the calculated values determined according to P‐V‐L theory, the Clausius‐Mossotti equation and IR fitted results. The larger bond energy for Mg–O bonds than for Ti–O bonds corresponds to a more stable octahedron of [MgO6], as verified by the octahedral distortion. Satisfactory microwave dielectric properties of Y2MgTiO6 ceramics were as follows: εr = 20.4 ± 0.8, Q × f = 42 060 ± 310 GHz, τf = −52 ± 3 ppm/°C, sintered at 1450°C.

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