Polarized Raman scattering in lanthanum gallogermanate glasses

Polarized Raman scattering has been used to characterize the structure of t wo series of lanthanum gallogermanate glasses with the composition xLa(2)O( 3)-GeO2-0.25Ga(2)O(3) and 0.33La(2)O(3)-GeO2-yGa(2)O(3), where x, y = 0.2, 0.25, 0.33, and 0.5, We assigned the vibrational modes to different types o f atomic motions in the glass network. No direct evidence of the six-fold c oordinated (octahedral) germanium or gallium ions in the glass structure ha s been observed. The nature of the low frequency Raman peak - the so called Boson peak - is discussed in terms of the existing theories. (C) 1999 Else vier Science B.V. All rights reserved.