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Phase transitions and amorphization of CaWO 4 at high pressure
Author(s) -
Errandonea Daniel,
Somayazulu Maddury,
Häusermann Daniel
Publication year - 2003
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200301412
Subject(s) - tetragonal crystal system , diamond anvil cell , monoclinic crystal system , amorphous solid , phase transition , materials science , phase (matter) , raman spectroscopy , crystallography , scheelite , high pressure , diffraction , quenching (fluorescence) , analytical chemistry (journal) , crystal structure , chemistry , thermodynamics , tungsten , optics , metallurgy , physics , organic chemistry , chromatography , fluorescence
The structural phase transitions in CaWO 4 were studied by in situ energy‐dispersive X‐ray diffraction in a diamond‐anvil‐cell under high pressure up to 65 GPa at room temperature. The previously reported phase transition detected by Raman spectroscopy at 10 GPa was observed in our experiments at 12 GPa and the high‐pressure phase was characterized. This transition is from the tetragonal scheelite structure (I4 1 /a) of CaWO 4 to a monoclinic wolframite‐type structure (P2/c) and a small discontinuity in the evolution of the unit‐cell volume was detectable during the transformation (Δ V / V < –1.9%). In addition, we observed that CaWO 4 becomes amorphous at pressures exceeding 40 GPa and found that a novel high‐pressure phase of CaWO 4 can be obtained at 45 GPa after heating to 477 K and quenching to room temperature an amorphous sample.