DETERMINATION OF STRUCTURAL-PROPERTIES OF K-GERMANATE GLASS BY OPTICAL MEASUREMENTS AND A POLARIZATION-OPTICAL TEST ON NANOCRYSTALLINITY

The bond-charge model is used to connect optical and structural proper ties of glasses. Its application to Vitreous K2Ce8O17 (v-KGO) indicate s the presence of 6-fold coordinated germanium in the glass although s uch octahedra are absent in the crystal of the same composition. It is speculated that clusters of GeO6/3 octahedra and even tetragonal GeO2 nanocrystals should occur. A polarization-optical method is presented to detect optical anisotropy originating in the inhomogeneity of the sample. II is based on a comparison between spontaneous and magnetic-f ield induced optical ellipticities. The experimental result is discuss ed as evidence for the appearance of nanocrystals in a concentration o f 10(-5) in v-RGO. (C) 1998 Elsevier Science B.V. All rights reserved.