Mössbauer study of iron impurities in cubic boron nitride

Abstract Local electronic states of 57 Fe and their thermal stability in cubic boron nitride (c-BN) samples prepared by catalytic synthesis and noncatalytic synthesis have been studied by transmission Mossbauer spectroscopy. In samples obtained by direct phase transformations (noncatalytic synthesis) iron forms mainly magnetically ordered phases of ϵ-Fe 3 N and amorphous a-(Fe–B) which decompose at elevated temperature to metallic iron precipitates. In samples prepared by catalytic synthesis the dominating, stable fraction of iron is paramagnetic Fe 3+ in low symmetry surrounding. These results may give some hints for the degradation in the mechanical properties of c-BN cutting edges.