The High Pressure Phase in the Chalcopyrite AgGaTe2

✍ Scribed by Y. Mori; S.-I. Iwamoto; K.-I. Takarabe; S. Minomura; A. L. Ruoff

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 168 KB
• Volume: 211
• Category: Article
• ISSN: 0370-1972
• DOI: 10.1002/(sici)1521-3951(199901)211:1<469::aid-pssb469>3.0.co;2-4

✦ Synopsis

High pressure X-ray diffraction measurements were performed on AgGaTe 2 chalcopyrite semiconductor up to 30 GPa; the space group and atomic positions under high pressure were refined by the Rietveld method. The first phase transition occurred at 3.1 GPa from the chalcopyrite phase to the coexisting phase of the P " 4 which is disordered zinc blende (d-B3) and a second phase which is not inconsistent with a Cmcm structure but this is by no means proven. Between 3.1 and 5.4 GPa, all three phases were apparent in the X-ray spectra until the chalcopyrite phase disappeared at 5.4 GPa. Using the Birch equation, the bulk moduli of the chalcopyrite, d-B3, and the very tentative Cmcm phases were determined to be 71.5, 55.2, and 34.0. GPa, respectively. Moreover, two high-pressure phases appeared around 8.5 GPa and these phases existed up to 30 GPa. One phase was assigned as the disordered NaCl (d-B1) structure. The d-B3± ±d-B1 transition was accompanied by a volume reduction of 8% which is compatible with the phase transition from a fourfold-coordinated phase to a sixford-coordinated phase transition.