X-RAY-DIFFRACTION STUDY ON MICROSTRUCTURE OF LI2O-TEO2 GLASSES

Since Li2O-TeO2 glasses have unique properties such as high densities, high refractive indexes, large dielectric constants and transmittance in a wide infrared wavelength region, much scientific attention has b een focused on the glasses from the standpoint of its technological ut ilizations. In spite of their usefulness, little diffraction work has been done about the short range structure of Li2O-TeO2 glasses. The st ructure of 15 mol%Li2O . 85 mol%TeO2 and 25 mol%Li2O . 75 mol%TeO2 gla sses was analyzed by an X-ray diffraction technique. Interpretation of the radial distribution function was performed on the basis of the co rrelation method. The following conclusions were obtained from the pre sent: study; (1) Two kinds of Te-O bond lengths of 0.18 nm and 0.20 nm are in TeO4 trigonal bipyramid. (2) As network forming units, the TeO 4 trigonal bipyramids and TeO3 trigonal pyramids are observed. The for mer units are thought to be transformed, via the transient species of polyhedra with non-bridging oxygens, into the latter units with increa sing Li2O contents, (3) The lone pairs of electrons on Te atoms do not contribute to the network formation.