Phase transitions in hydroxide perovskites: A Raman spectroscopic study of stottite, FeGe(OH) 6, to 21 GPa

A. K. Kleppe, M. D. Welch, W. A. Crichton, A. P. Jephcoat

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    9 Citations (Scopus)

    Abstract

    The effect of pressure on the naturally occurring hydroxide-perovskite stottite, FeGe(OH) 6, has been studied in situ by micro-Raman spectroscopy to 21 GPa at 300 K. The ambient spectrum contains six OH-stretching bands in the range 3064 3352 cm -1. The presence of six non-equivalent OH groups is inconsistent with space group P4 2/n. In view of this inconsistency a new ambient structure determination of stottite from Tsumeb was carried out, but this did not allow the clear rejection of P4 2/n symmetry. However, a successful refinement was also carried out in space group P2/n, a subgroup of P4 2/n, which allows for six non-equivalent O atoms. The two refinements are of comparable quality and do not allow a choice to be made based purely on the X-ray data. However, taken with the ambient and 150 K Raman spectra, a good case can be made for stottite having P2/n symmetry at ambient conditions. On this basis, the pressure induced spectroscopic changes are interpreted in terms of a reversible phase transition P2/n ↔ P4 2/n.

    Original languageEnglish
    Pages (from-to)949-962
    Number of pages14
    JournalMineralogical Magazine
    Volume76
    Issue number4
    DOIs
    Publication statusPublished - Aug 20 2012

    Keywords

    • Raman spectroscopy
    • X-ray diffraction
    • diamond-anvil cell
    • high-pressure
    • hydroxide perovskites
    • stottite

    ASJC Scopus subject areas

    • Geochemistry and Petrology

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