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APS » Journals » Phys. Rev. Lett. » Volume 56 » Issue 18
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Phys. Rev. Lett. 56, 1944–1947 (1986)

Phase-Transition Studies of Germanium to 1.25 Mbar

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Yogesh K. Vohra, Keith E. Brister, Serge Desgreniers, and Arthur L. Ruoff
Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853

K. J. Chang and Marvin L. Cohen
Department of Physics, University of California, Berkeley, California 94720
Materials and Molecular Research Division, Lawrence Berkeley Laboratory, Berkeley, California 94720

Received 16 December 1985; revised 25 February 1986; published in the issue dated 5 May 1986

New phase transitions in Ge were observed by energy-dispersive x-ray diffraction techniques for pressures up to 125 GPa (1.25 Mbar) as follows: the β-Sn structure to the simple hexagonal (sh) phase at 75 ± 3 GPa and to the double hexagonal close-packed structure (dhcp) at 102 ± 5 GPa. These are the highest pressures for which a crystalline structure change has been directly observed by x-ray diffraction. Total-energy pseudopotential calculations predict 84 ± 10 GPa for the β-Sn to sh phase transition and 105 ± 2 GPa for sh to hcp (not dhcp) transition. The role of 3 d core electrons in increasing the transformation pressures in Ge, as compared to Si, is emphasized.

© 1986 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.56.1944
DOI:
10.1103/PhysRevLett.56.1944
PACS:
64.70.Kb, 62.50.+p, 64.30.+t
 
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