Computer simulation on the structure and vibrational spectra in GePbOF glass

Oxy-fluoride glasses in the GeO₂PbOPbF₂ system were prepared and their structure investigated using vibrational spectra, X-ray diffraction and Raman spectra methods. Structural models were constructed by molecular dynamics simulations. In the models obtained, glass networks were formed by GeO₄ tetrahedra and Ge(O,F)₅ and Ge(O,F)₆ polyhedra. Lead entered the networks at PbFPb in the models with high Pb/Ge ratio. The presence of germanium with high coordination numbers of 5 and 6 was supported by radial distribution analyses. GeO bonds in GeO₄ tetrahedra seemed to give bands between 650 and 850 cm^-1 (non-bridging oxygen) and between 450 and 650, and between 850 and 950 cm^-1 (bridging oxygen). GeO and GeF in Ge(O,F)_n (n > 4) were supposed to contribute the bands observed between 350 and 550 cm^-1 in the Raman spectra.