Effects of CeO2 nanoparticles and annealing temperature on the microwave dielectric properties of MgTiO3 ceramics

Abstract

Abstract MgTiO 3 (MTO) ceramics have been prepared by the conventional solid-state reaction method. The effects of CeO 2 nanoparticles up to 1.5 wt% as a sintering aid and annealing temperature on the crystal structure, microstructure and microwave dielectric properties of MTO ceramics were investigated. It is found that the addition of CeO 2 nanoparticles to the MTO ceramics leads to improvement in the relative density, reduction in sintering temperature. However, Q × f o values are found to decrease marginally. The driving forces for the improved sintering process are the large surface energy of CeO 2 nanoparticles and their defect energy, which are activated during the sintering process. The addition of CeO 2 nanoparticles does not change the dielectric constant ( e r ), and the unloaded quality factor ( Q u ) but the τ f values are altered significantly. The annealing temperatures of the pure MTO ceramics and MTO+ x CeO 2 ( x =0.5, 1.0 and 1.5 wt%) were optimized. The samples annealed at 1100 °C for 48 h exhibit the best microwave dielectric properties. The maximum value of Q × f o for the pure MTO was achieved by sintering at1400 °C and significantly such maximum value was achieved in x =0.5 wt% sample by sintering at 1300 °C itself. The values of Q × f o are in the range of 52250–140800 GHz. Pure MTO ceramics sintered at 1400 °C and annealed at 1100 °C for 48 h exhibit the best microwave dielectric properties ( e r =17.21, Q × ƒ o =165500 GHz). The observed results are correlated to the reduction in oxygen vacancies, relaxation of strain during annealing, increase in grain size and relative densities.