The coordination of Ni11 in glasses and glass-ceramics of the system MgOAl2O3SiO2

Differences in strength connected with colour variations in NiO-containing Mg-alumosilicate glass ceramics give rise to a remission spectroscopic analysis of the Ni-on. In the base glass, Ni¹¹ occupies tetrahedral and octahedral positions of the dark green NiAl spinel. An increase of the Mg-component and a rise of the melting intensity promote the octahedral nickel coordination and along with it the formation of the strength-reducing, light green Ni-forsterite. The demand for a strong final product is thus met by the technologically desirable shortening of the melting time.