STRUCTURAL STUDY ON GA2O3-TEO2 GLASSES

Glasses of the xGa(2)O(3).(100-x)TeO2 system (x=5-35 mol%) were invest igated by infrared (IR), Raman and x-ray photoelectron spectroscopy (X PS) in an attempt to determine the structural units and their relation to the vitrification ability. Infrared spectra revealed that the addi tion of Ga2O3 increased the fraction of TeO3 groups in the tellurite n etwork. High intensity Raman bands were observed. The vibrations in th e 400-500 cm(-1) range were assigned to the modes of highly polarisabl e bridging Ga-O-Te and Te(1)-O-Te(2) bonds. The binding energies (BE) of O 1s, Te 3d and Ga 3d core level electrons were measured and analys ed. The variation in O 1s BE was found to correlate with the optical b asicity change in glasses. The Te 3d spectra indicate that together wi th Te4+, Te6+ ions are also formed. By analogy with the structural che mistry of crystalline tellurites it was assumed that polyanions compri sing TeO4 and TeO3 polyhedra are the main building blocks in glass str ucture. The binding of the tellurite complexes in the network is achie ved via mixed Ga-O-Te bridge bonds.