Structural Properties of GeSe2 at High Pressures

✍ Scribed by Tor Grande; Motohiko Ishii; Minoru Akaishi; Siv Aasland; Helmer Fjellvåg; Svein Stølen

• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 214 KB
• Volume: 145
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1999.8235

✦ Synopsis

Crystalline and glassy GeSe 2 have been subjected to pressures up to 7.7 GPa and temperatures up to 11003C using a highpressure belt-type apparatus. Two high-pressure crystalline polymorphs of GeSe 2 have been synthesized. The crystal structure of the tetragonal form of GeSe 2 prepared at 3.0 GPa and 5003C, with space group I-42d and a ‫؍‬ 5.7307(4) and c ‫؍‬ 9.691(1), was determined by means of powder X-ray di4raction data. The structure consists of GeSe 4 tetrahedra that share corners in a three-dimensional network and has a considerably higher density than the two-dimensional structure of ambient-pressure GeSe 2 consisting of both edge-and corner-sharing tetrahedra. The IR and Raman spectra of tetragonal GeSe 2 are discussed in relation to the structure of GeSe 2 glass. An orthorhombic polymorph of GeSe 2 was formed during quenching from 7.7 GPa and 5003C. Amorphous GeSe 2 compressed at 250+3003C was observed to partly crystallize at 3.0 and 7.7 GPa.