INTERSTITIAL INCORPORATION OF DI- AND TRIVALENT COBALT IN QUARTZ

Trivalent cobalt in synthetic quartz shows absorption bands of a distorted octahedral complex indicating interstitial incorporation of this ion. Upon heating the cobalt is reduced to the divalent state. The absorption spectrum is now identical to that of synthetic quartz doped with divalent cobalt. It is compatible with a tetrahedral or cubic site symmetry and has been attributed to Co2+ substituting Si4+ in the lattice. From kinetic considerations and the experimental Dq value as well as the similarity of the spectrum of Co2+ in high alkali glasses it is concluded that the divalent cobalt occupies an interstitial position of distorted tetrahedral symmetry arising from the octahedral site by a displacement of c/6 along the c axis channels of the quartz structure. © 1969.