Microwave dielectric properties of temperature stable (1-x)SrLaAlO4-xTiO2 composite ceramics

Abstract Dense (1-x)SrLaAlO4-xTiO2 (x = 0, 0.05, 0.10, 0.15) composite ceramics were prepared via a standard solid-state reaction method. The effect of TiO2 addition on the sintering behavior, phase composition, microstructure and microwave dielectric properties of SrLaAlO4 ceramics were systematically investigated. The X-ray diffraction patterns revealed the co-existence of the two phases and the microstructure evolutions were observed using scanning electron microscopy analysis. The dielectric constant of the present ceramics increased from 17.5 at x = 0–21.2 at x = 0.15, and the negative temperature coefficient of resonant frequency of SrLaAlO4 ceramics (–30 ppm/°C) could be modified towards positive. Empirical models such as Lichtenecker logarithmic model and mixing rule were applied to explain the variation trend of the microwave dielectric properties in the present ceramics. The optimum microwave dielectric properties were achieved at x = 0.10 (er = 20.2, Qf = 79,500 GHz, τf = 8 ppm/°C).