Enhanced microwave dielectric and electrical properties of Zn substituted Mg 2 TiO 4 ceramics for RF/microwave applications

The structural, microstructural, electrical and microwave dielectric properties of Mg 2 Ti 1− x Zn x O 4 ( x = 0.01–0.05) ceramics prepared by solid-state reaction method have been reported. The X-ray diffraction patterns and Raman spectra have showed the presence of pure Mg 2 TiO 4 (MMTO) along with some fraction of MgTiO 3 (MTO) phase. It is observed that the cubic structure of MMTO is deformed and evaluated to become pseudo cubic structure with Zn substitution. The surface morphology of the sintered MMTO ceramics at 1350 °C exhibited uniform and dense microstructures. Temperature dependent dielectric response of Mg 2 Ti 1− x O 4 Zn x ceramics with x = 0.03, showed stable dielectric response in the temperature range from RT to 300 °C. The overall enhancement in dielectric response of the samples is attributed to the compositional heterogeneity due to substitution of Zn 2+ in the Ti 4+ site. The complex impedance spectra revealed two parallel RC combination circuit [(R g C g ) (R gb C gb )] elements in series. The dispersion of AC conductivity followed Jonscher’s power law, and non-overlapping small polaron hole hopping assisted conductivity. Mg 2 Ti 1− x Zn x O 4 ceramics with x = 0.03, exhibited best structural, dielectric and microwave dielectric property with uniform and dense microstructure, moderate dielectric constant ( ε r ) ~ 23 and quality factor ( Q × f o ) ~ 165 THz at 8.89 GHz. A voltage independent capacitance for the sample at all the measured frequencies have observed. The obtained properties of the ceramics are promising for dielectric resonator, microwave integrated circuit and type-I capacitor applications.