Effect of Increasing Calcination Temperature and Partial Doping of Cobalt on the: Phase, Microwave Dielectric Properties, and Microstructure of the MgTiO3 Solid Ceramics.

Cobalt-doped magnesium titanate ceramics were synthesized using the conventional solid-state route with high-purity oxides from Aladdin Company. Cobalt was added in small amounts to enhance the unloaded quality factor of the material. The mixed powders were preheated at 1150°C for phase formation but failed to eliminate the MgTi2O5 secondary phase. Specimens were sintered between 1325°C and 1425°C for pellet solidification. XRD and SEM analyses confirmed the development of two phases in the ceramics. The highest bulk density was achieved at 1400°C, with a relative density of 91.90%. Theoretical density was also calculated for the cobalt-doped samples. Cobalt doping significantly improved the dielectric properties of the ceramics, with a Qufo value reaching 197,000 GHz. Additionally, slight increases in the dielectric constant (εr) and temperature coefficient of resonant frequency (tf) were observed, demonstrating the beneficial effects of cobalt doping on magnesium titanate ceramics.