Phase Relations in Si–C–N–O–R (R = La,Gd,Y) Systems

Abstract

The present work determined the phase relations in the Si–C–N–O–R systems, involving SiC–Si3N4–R2O3, Si3N4–SiO2–R2O3, and SiC–Si3N4–SiO2–R2O3 (R = La,Gd,Y) systems by XRD phase analyses of the solid‐state reacted samples from powder mixtures of SiC, Si3N4, and R2O3. Subsolidus phase diagrams of these systems were presented and summarized. Within these systems in‐situ SiO2 impurity in the powder mixtures often cause the formation of some oxygen‐richer rare‐earth siliconoxynitrides, J‐, K‐, H‐phases and extends the ternary systems SiC–Si3N4–R2O3 into the quaternary systems SiC–Si3N4–SiO2–R2O3 (Si–C–N–O–R). In these systems, the reaction of partial SiC participation and the formation mechanism of rare‐earth siliconoxynitrides are discussed.