Structural, vibrational and microwave dielectric properties of (1 - x)Mg_(0.95)Co_(0.05)TiO_3 - (x)Ca_(0.8)Sr_(0.2)TiO_3 ceramic composites

摘要

In this paper the structural, vibrational and microwave dielectric properties of (1 - x)Mg_(0.95)Co_(0.05) TiO_3 - (x)Ca_(0.8)Sr_(0.2)TiO_3 composites, prepared by the conventional solid state route have been investigated. The X-ray diffraction patterns of these composites confirm the coexistence of ilmenite-structured Mg_(0.95)Co_(0.05)TiO_3 and perovskite-structured Ca_(0.8)Sr_(0.2)TiO_3 phases. The Rietveld analysis of the XRD data has been carried out for structural refinement of the phases. The microwave dielectric properties of the grown samples have been thoroughly studied using Hakki-Coleman dielectric resonator method. A good combination of dielectric properties with relative permittivity (ε_r) of 21.55, quality factor (Q×f) of 98,885 GHz (at 7.5 GHz) and a temperature coefficient of resonant frequency (T/) of 0.81 ppm/°C have been obtained for 0.93Mg_(0.95)Co_(0.05)TiO_3-0.07Ca_(0.8)Sr_(0.2)TiO_3 composite, sintered at 1275 °C for 4h. The theoretical relative permittivity of these composites has been calculated using various mixing formulae based on the effective medium models.