Microwave dielectric properties of (1 − x)MgTiO3−x(Ca0.6Na0.2Sm0.2)TiO3 ceramic system

The microstructures and microwave dielectric properties of (1 − x)MgTiO3–x(Ca0.6Na0.2Sm0.2)TiO3 ceramics prepared by the conventional solid-state reaction route have been investigated with the variation of x as well as sintering temperature, aiming to achieve a material with a high quality factor and nearly zero temperature coefficient of resonant frequency (τf). The crystalline phases and the microstructures of the ceramics have been characterized by means of X-ray diffraction and scanning electron microscopy. The microwave dielectric properties of the ceramic system have been found strongly related to the density, sintering temperature, x value, second phase as well as the microstructure of the ceramic samples. The 0.89MgTiO3–0.11(Ca0.6Na0.2Sm0.2)TiO3 ceramic system, sintering at 1250 °C for 4 h, showed excellent microwave dielectric properties with εr ~ 22.8, Q × f ~ 76000 GHz (at 8 GHz) and τf ~ −3.1 ppm/°C. It could be a suitable candidate material for microwave applications. Moreover, the theoretical dielectric constant of this system has been calculated using various mixing formulae based on the effective medium models.