ISSN 0004-881X

An Investigation of the Solid Solubility Between Aluminium Oxynitride and Magnesium Aluminate Spinels

by N. Rigopoulos¹, R.G. O'Donnell¹, A Oh¹ and M.B. Trigg^1,2

1) CSIRO Materials Science and Engineering, Australia
2) AutoCRC, Port Melbourne, Australia

Abstract

A range of stoichiometric mixtures of AlON spinel and magnesium aluminate spinel were prepared from precursor powders via sintering. XRD results showed the mixtures to be single phase and hence confirmed the complete solid solubility between these two species. NMR was used to identify the distribution of the Al atoms onto the tetrahedrally and octahedrally coordinated sites within the spinel lattice. Al cations were determined to exist on both the tetrahedral and octahedral sites across the complete solid solution range. Tetrahedral site occupancy increased with increasing AlON content although vacancies are predicted to occupy some tetrahedral sites in the 100% AlON spinel. The presence of Al atoms in tetrahedral coordination within the 100% magnesium aluminate spinel indicates that some Al atoms are disordered onto sites consistent with an inverse spinel configuration. The degree of disordering is observed to persist through the full range of solid solution between these phases.

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