Local atomic arrangement in Ge-Te and Ge-S-Te glasses

• Published in: Journal of non-crystalline solids 1996-10, Vol.205, p.189-193
• Main Authors: Uemura, O., Hayasaka, N., Tokairin, S., Usuki, T.
• Format: Article
• Language: English
• ISSN: 0022-3093; 1873-4812
• DOI: 10.1016/S0022-3093(96)00376-6

X-ray diffraction and Raman spectroscopic studies have been made on Ge x Te 1 − x ( x = 0.16–0.20) and Ge(S 1 − x Te x ) 2 ( x = 0–0.75) glasses. The position and width of the first peak in g(r) in Te-enriched Ge-Te glasses vary with composition, suggesting that the nearest neighbor shell in the glass contains more than one atomic correlation, namely Ge-Te and Te-Te. It was indicated by a least squares analysis of intensity functions that each Ge atom is surrounded by four Te atoms, implying that the chemically ordered 4-2 coordination model is favored in Ge-Te glasses. Results of both the Raman spectrum and diffraction intensity analysis on Ge(S 1 − x Te x ) 2 glasses show that basic structural units in the glasses are anion-mixed tetrahedra, Ge(S (4 − n)/2 Te n/2) type where n = 0 ~ 4, with a Ge atom in the central site. The results agree with the case in Ge(S 1 − x Se x ) 2 glasses. However, S-enriched anion-mixed units, for example, n = 1 or 2 type, are not formed in the present telluride glass, due to a considerable difference in atomic size between S and Te.