Effect of thermal annealing on dielectric property and thermal conductivity of Si3N4-BaTiO3 composite ceramics

Si3N4-BaTiO3 composite ceramics were prepared by hot pressing sintering. The effects of the amount of BaTiO3 and annealing process on the microstructure, phase composition, dielectric properties and thermal conductivity of Si3N4 composite ceramics were studied. With the increase of BaTiO3 content, the density and the dielectric performance of the Si3N4-based composite ceramics are improved, while the thermal conductivity is reduced. The annealing treatment can not only inhibit the growth of beta-Si3N4, refine the grain, reduce the content of intercrystalline glass phase and porosity, but also promote the precipitation of hexagonal barium titanate, all of which are beneficial to increase the dielectric constant and decrease the dielectric loss, but will slightly reduce the thermal conductivity of Si3N4-BaTiO3 composite ceramic. The sample A2BT15 with 15% BaTiO3 sintered at 1750 degrees C for 2 h and annealed at 1300 degrees C exhibited the maximum dielectric constant (epsilon = 10.57), the minimum dielectric loss (tan delta = 9x10(-4)), a high relative density (98.8%) and an acceptable thermal conductivity (14.5 W.m(-1).K-1). Therefore, the selection of appropriate BaTiO3 content and annealing process can regulate the dielectric property, thermal performance and mechanical property of Si3N4-BaTiO3 composite ceramics in a certain range.

Automated summary

The effects of BaTiO3 content and annealing process on the microstructure, phase composition, dielectric properties and thermal conductivity of Si3N4-BaTiO3 composite ceramics were studied. Increasing BaTiO3 content improved the density and dielectric performance but reduced the thermal conductivity. Annealing treatment improved the structure and properties, but slightly reduced thermal conductivity.