Formation, properties and structure of barium titanate glasses

The aim of this study was to produce high TiO_2 content (30-60wt%)glasses. Stable titanate glasses with high content of TiO_2 and BaO could be obtained even without the other glass-forming oxides. The synthesized glasses had high refractive index(n_D>2.1) and good chemical durability. It has been demonstrated that the coloration of titanate glasses with high TiO_2 content is due to the oxygen losses during the melting process. A systematic controlling of melting process and heat treatment has led to the successful decoloration of high TiO_2 containing glasses. At the same time the reflectance increased. Infrared and X-ray diffraction spectra showed that Ti~(4 ) in titanate glasses is in sixfold coordination.The crystallization of titanate glasses is generally preceded by the phase separation. By electron microscopy the phase separation of the titanate glasses was observed to take place during the heat treatment at the temperature above T_g. The resulted crystalline phases are mainly different titanates. Based upon the vibrational spectra, a schematic model of structure of titanate glasses is proposed.