Effects of MgO addition on the density and dielectric loss of AlN ceramics sintered in presence of Y2O3

In the present work, effects of sintering additives on dielectric loss tangent of AlN ceramics were explored. Different amounts of Y2O3 and MgO were respectively added as sintering additives to AlN powder, and pressureless sintering was performed in a nitrogen flow atmosphere at 1850 °C or 1900 °C for 2 h. The resulted AlN ceramics became denser due to addition of MgO, and a full dense sinter was obtained at a relative density of 0.998. Tan δ decreased with increasing MgO amount when kept Y2O3 content and the sintering temperature at 1 mol% and 1900 °C, respectively.