TiO₂-assisted Mg-Ti-O-based ceramics improve thermal conductivity and microwave dielectric properties by modifying the microstructure

The influence of TiO₂ on the crystal phase, microstructure, thermal conductivity, and microwave dielectric properties of Mg-Ti-O-based ceramics during sintering are explored. XRD analysis reveals that doped TiO₂ completely reacts with Mg₂TiO₄ to generate MgTiO₃, and (1-y)Mg₂TiO₄ + yMgTiO₃ ceramics are obtained. The undoped TiO₂ samples exhibit an excessively large grain size with an uneven grain size distribution and numerous pores. The reaction between TiO₂ and Mg₂TiO₄ effectively reduces the grain size of Mg₂TiO₄ to a reasonable range, thereby facilitating the mitigation of internal defects within grains. Additionally, the formation of MgTiO₃ results in a microstructure characterized by two phases with staggered distribution and mutual inhibition. This phenomenon aids in controlling the growth and arrangement of grains, ultimately filling pores and enhancing ceramic density. A reasonable grain size and regular arrangement are advantageous for improving the thermal and dielectric performance of ceramics compared to excessively larger grains and uneven distribution. Mg-Ti-O-based ceramics contribute to an enhancement in thermal conductivity to 10.1 W/(m·K) and in Q×f value to 143,046 GHz.