Phase Relations in SiC-AlN-R2O3 (R = Nd, Gd, Yb, Y) Systems

Abstract

The phase relations in SiC-AlN-R2O3 (R = Nd, Gd, Yb, Y) systems were determined by XRD and EPMA analyses of the solid-state reacted samples from powder mixtures of SiC, AlN and various R2O3. Subsolidus phase diagrams of these systems were established. In the Nd-system by Si-C partially substituted for Al-N in Nd2AlO3N, the formation of solid solution with formula Nd2Al1−xSixO3N1−xCx (x = 0-0.5) was first found. Impurities of Al2O3 and SiO2 from AlN and SiC starting powders respectively often caused the formation of some salt compounds, RAP type (R = Nd) and RAM type (R = Gd, Yb, Y), in corresponding systems. Mechanism of the reactions of forming salt compounds and their relations with rare earth oxides series are discussed.