Effect of zirconia addition on dielectric loss and microstructure of aluminum nitride ceramics

The effects of sintering additives on dielectric loss tangent of AlN ceramics have been investigated. Different amounts of Y2O3 and ZrO2 were added as sintering additives to AlN powder and pressureless sintering was performed at 1900 °C for 2 h in a flowing nitrogen atmosphere. ZrN phase was detected in AlN ceramics when ZrO2 addition was more than 0.1 mol.%. Densification behavior of both Y2O3 and ZrO2 doped AlN ceramics was found to be a little complicated, however addition of ZrO2 was effective in the densification of the AlN ceramics. tan δ is found to increase from less than 1 × 10−3 to around 6 × 10−3 when ZrO2 content was more than 0.1 mol.%.