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Pressure Induced Phase Transitions in Alkaline Earth Tungstates
Author(s) -
Christofilos D.,
Ves S.,
Kourouklis G. A.
Publication year - 1996
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.2221980172
Subject(s) - alkaline earth metal , phase (matter) , earth (classical element) , materials science , geology , environmental science , chemistry , physics , metallurgy , organic chemistry , mathematical physics , metal
We present a Raman study of the pressure induced structural phase transitions in the tungstates CaWO 4 and SrWO 4 . Raman spectra up to 24 GPa at room temperature reveal reversible pressure induced phase transitions at 10 and 11.5 GPa for CaW) 4 and SrWO 4 , respectively. The lowest B g mode, associated with the WO 4 ‐WO 4 vibration along the c ‐axis, exhibits a softening in the scheelite structure, while in the high‐pressure phase its slope becomes positive. Above the phase transition the modes originating from the antisymmetric v 3 (E g ) and v 3 (B g ) stretching modes of the WO 4 group exhibit a frequency jump to higher and lower frequencies. In the high pressure phase the modes originating from v 3 show an unusual, strongly nonlinear softening in a small pressure region before becoming almost pressure independent.