Dielectric properties of sintered aluminum nitride

In the present work, the effects of sintering additives on dielectric loss tangent (tan δ) of AlN ceramics were explored. Different amounts of Y2O3 and Mg3N2 were respectively added as sintering additives to AlN powders, and pressureless-sintering was performed at 1900 °C for 2 h in a nitrogen flow atmosphere. The resulted AlN ceramics became denser due to the addition of Mg3N2, and nearly fully dense sample was obtained with a relative density of 0.998. tan δ decreased with increasing Mg3N2 amount and it was found to depend on the density of the AlN ceramic. The best tan δ value of 3.9 × 10−4 was obtained by adding 1 mol% of Y2O3 and Mg3N2 together.