NEUTRON-DIFFRACTION AND SOLID-STATE MAS-NMR STUDIES OF THE STRUCTURE OF Y-AL-SI-O-N OXYNITRIDE GLASSES

Neutron diffraction and magic angle spinning (MAS) Al-27 and Si-29 NMR have been applied to study the local structure of glasses in the system Y-Al-Si-O with and without addition of AlN. Al-27 MAS NMR indicated that in the Y-Al-Si-O-N oxynitride glass there is no Al-N bonding and aluminium atoms occupy various sites within the glass structure. The first peak of the radial distribution function curves obtained by neutron diffraction was deconvoluted into four peaks which are attributable to Si-O, Si N(Al-O(4)), Al-O(5) and Al-O(6) pairs and the coordination numbers of Si, N, Al and Y were estimated. The glass network is assumed to consist mainly of corner-sharing AlO4 tetrahedra and SiO3N tetrahedra. 86% of N atoms are three-coordinated and 14% of N atoms are two-coordinated in the present oxynitride glass.