ELECTRON-DIFFRACTION STUDY OF THE SHORT-RANGE ORDER IN GLASSES OF THESYSTEM TEO2-B2O3

The short-range order in vitreous TeO2 and B2O3 and in TeO2-B2O3 glass es has been studied using electron diffraction. The amorphous samples investigated were prepared by two methods. Powdered samples were produ ced either by rapid quenching using the roller technique (TeO2 glass) or by slow cooling (B2O3 and TeO2-B2O3 glasses) and amorphous TeO2 and TeO2-B2O3 thin films were deposited by vacuum evaporation with resist ive heating. According to the electron diffraction data, the TeO, poly hedron is shown to be the main structural unit in the TeO, glass. The boron atoms in the B2O3 glass are found to be threefold-coordinated wi th respect to the oxygen and the presence of B3O6 groups is indicated. In the binary glasses mainly Te-O or B-O distances are resolved, depe nding on their composition. The results for the powdered and thin film samples are compared and a change in the Te-O distances for the films is established.