Raman spectroscopic studies of BaOGa2O3GeO2 glasses

Abstract

Raman spectra were collected for barium gallogermanate glasses along two compositional joins to determine relationships among glass structure, chemistry, and physical property variations. As GeO 2 content decreases for both glass series, the mid-frequency envelope shifts to higher frequencies while the high-frequency features increase in intensity and shift to lower frequencies. These trends in the Raman spectra parallel those reported for binary Li, Na and K germanate glasses, and are interpreted in terms of a reduction in average ring size, as well as an average lengthening of TO bonds. The more extreme trends for the most barium-rich glasses indicate partial depolymerization of the tetrahedral network and a concomitant increase in the number of non-bridging oxygens. There is no evidence for octahedral Ge or Ga in any of the barium gallogermanate glasses investigated in this study. The findings determined from the Raman data are consistent with earlier conclusions drawn from Ge and Ga X-ray absorption spectra.