Refinement of the α-Phase Area in the Yb-SiAlON System

The composition and lattice parameters of several Yb‐SiAlON materials are reported. Electron microprobe analysis was used to measure the compositions of each phase, as this technique avoided the peak overlap problems encountered when using energy‐dispersive spectroscopy. A refined set of equations relating the composition of Yb‐α‐SiAlON to its lattice parameters is presented. The amount of oxygen substitution (n value) in α‐SiAlON has an effect on lattice parameters that is almost as strong as the amount of Al and Yb substitution (m value). The α‐SiAlON phase stability region is shown to extend much closer to the Si3N4‐4/3(AlN:Al2O3) line than reported previously.