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Title: Phase stability of iron germanate, FeGeO 3, to 127 GPa

The high-pressure behavior of germanates is of interest as these compounds serve as analogs for silicates of the deep Earth. Current theoretical and experimental studies of iron germanate, FeGeO 3, are limited. Here in this paper, we have examined the behavior of FeGeO 3 to 127 GPa using the laser-heated diamond anvil cell combined with in situ synchrotron X-ray diffraction. Upon compression at room temperature, the ambient-pressure clinopyroxene phase transforms to a disordered triclinic phase [FeGeO 3 (II)] at ~ 18 GPa in agreement with earlier studies. An additional phase transition to FeGeO 3 (III) occurs above 54 GPa at room temperature. Laser-heating experiments (~ 1200–2200 K) were conducted at three pressures (33, 54, and 123 GPa) chosen to cover the stability regions of different GeO 2 polymorphs. In all cases, we observe that FeGeO 3 dissociates into GeO 2 + FeO at high pressure and temperature conditions. Neither the perovskite nor the post-perovskite phase was observed up to 127 GPa at ambient or high temperatures. The results are consistent with the behavior of FeSiO 3, which also dissociates into a mixture of the oxides (FeO + SiO 2) at least up to 149 GPa.
Authors:
ORCiD logo [1] ;  [1] ;  [2] ;  [3] ;  [4] ;  [1]
  1. Princeton Univ., NJ (United States). Department of Geosciences
  2. Princeton Univ., NJ (United States). Department of Chemistry; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)
  3. Argonne National Lab. (ANL), Argonne, IL (United States); Univ. of Chicago, IL (United States). GeoSoilEnviroCARS
  4. Princeton Univ., NJ (United States). Department of Chemistry
Publication Date:
Grant/Contract Number:
AC02-05CH11231; FG02-94ER14466
Type:
Accepted Manuscript
Journal Name:
Physics and Chemistry of Minerals
Additional Journal Information:
Journal Volume: 45; Journal Issue: 4; Journal ID: ISSN 0342-1791
Publisher:
Springer
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 58 GEOSCIENCES; Germanates; Phase-transitions; Diamond anvil cell; High-pressure
OSTI Identifier:
1440960