First-principles prediction of post-pyrite phase transitions in germanium dioxide

Haruhiko Dekura (出倉春彦), Taku Tsuchiya (土屋卓久), and Jun Tsuchiya (土屋旬)
Phys. Rev. B 83, 134114 – Published 12 April 2011

Abstract

Two high-pressure phase transitions in GeO2 have been discovered through first-principles computer simulations: the first is a transition from the pyrite-type (FeS2) to cotunnite-type (α-PbCl2) structure predicted to occur at a pressure of ∼300 GPa, and the second is a transition from the cotunnite-type to the hexagonal Fe2P-type structure at ∼600 GPa. The former is accompanied by a remarkable volume reduction of 5.4%, while the latter has a distinctive but quite small volume change of 0.3%. The post-pyrite transition to the cotunnite-type structure is expected from known high-pressure behavior of other dioxides, while the post-cotunnite transition to an Fe2P-type structure is quite unexpected, with no report in any dioxides so far except for a recent study on SiO2. The Fe2P-type phase has higher effective coordination numbers of Ge atoms, which contributes to stabilizing this structure relative to cotunnite. The results obtained extend our knowledge of the ultrahigh-pressure crystallography of dioxide materials.

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  • Received 14 September 2010

DOI:https://doi.org/10.1103/PhysRevB.83.134114

©2011 American Physical Society

Authors & Affiliations

Haruhiko Dekura (出倉春彦)1, Taku Tsuchiya (土屋卓久)2, and Jun Tsuchiya (土屋旬)1

  • 1Senior Research Fellow Center, Ehime University, 2-5 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan
  • 2Geodynamics Research Center, Ehime University, 2-5 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan

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Issue

Vol. 83, Iss. 13 — 1 April 2011

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