Structural changes of quartz-type crystalline and vitreous GeO2 under pressure

• Published in: Journal of synchrotron radiation Vol. 8; no. 2; pp. 791 - 793
• Main Authors: Ohtaka, Osamu, Yoshiasa, Akira, Fukui, Hiroshi, Murai, Kei-ichiro, Okube, Maki, Katayama, Yoshinori, Utsumi, Wataru, Nishihata, Yasuo
• Format: Journal Article
• Language: English
• Published: 5 Abbey Square, Chester, Cheshire CH1 2HU, England Munksgaard International Publishers 01.03.2001
• Subjects: Crystal structure; Germanium oxides; Synchrotron radiation
• ISSN: 1600-5775; 0909-0495; 1600-5775
• DOI: 10.1107/S0909049500018306

Using a large volume high pressure apparatus, quartz‐type crystalline GeO2 and Li2O‐4GeO2 glass have been compressed up to 14 GPa at room temperature and their local structural changes have been investigated by an in‐situ XAFS method. In quartz‐type crystalline GeO2, the change of the coordination number from 4 to 6 begins above 8 GPa and finishes below 12 GPa. On decompression, reversal transition begins below 8 GPa and there is a large hysteresis. Almost no sixfold coordination of Ge is preserved after releasing pressure. Change of coordination number in vitreous Li2O‐4GeO2 begins above 6 GPa and is completed below 10 GPa. Reversal transition begins below 10 GPa and the hysteresis is smaller than that of quartz‐type GeO2. Change of coordination number in vitreous Li2O‐4GeO2 is also reversal.