Influence of TiB2 content and powder size on the dielectric property of TiB2/Al2O3 composites

TiB2/Al2O3 composites were prepared by hot-pressed sintering using TiB2 and Al2O3 powders. The dielectric property of these composites was investigated. The mechanisms of polarization and microwave energy loss were discussed. Both the real part of dielectric constant and the energy loss increase greatly with increasing TiB2 content over the frequency range 8.2–12.4 GHz. Movement and accumulation of valence electrons in TiB2 powders caused the polarization and energy loss. The formation of a TiB2 local network is responsible for the marked increase in the dielectric constant.