Effect of Rare Earth Oxides on Electrical Properties of Spark Plasma Sintered AlN Ceramics

Abstract

AlN ceramics doped with rare earth oxide (Sm2O3, Y2O3) were prepared by Spark Plasma Sintering (SPS) in nitrogen atmosphere using AlN powder as raw materials. The effect of rare earth oxide on the phase composition, microstructure and electrical resistivity of AlN ceramics were investigated. The results showed that those sintering additives promoted densification through liquid-phase sintering. AlN ceramics with electrical resistivity values of 1×10–1×10 Ω•cm were obtained by precipitating rare earth aluminates as a conducting pathway at the grain boundaries. With the increasing of Sm2O3 doping, the phase of samarium aluminate gradually changed from Sm4Al2O9 to SmAlO3 which had a higher resistivity than Sm4Al2O9. 3wt% Sm2O3 doped AlN ceramics had the minimum resistivity of 1.32×10 Ω•cm with the relative density of 99.33%. The yttrium aluminate phase gradually changed from Y3Al5O12 to Y4Al2O9 with the increase of Y2O3-doping. The electrical resistivity of different yttrium aluminates were about 1× 10 Ω•cm. Y2O3doped AlN sample with over 3wt% Y2O3 had an electrical resistivity about 1×10 Ω•cm. 4wt% Y2O3 doped AlN ceramic had the electrical resistivity of 1.60×10 Ω•cm with the maximum relative density of 99.08%. 268 无 机 材 料 学 报 第 30卷