Pressure-driven Phase Transition in CaFeAsF at 40 and 300 K

Mishra, S. K.; Chaplot, S. L.; Garbarino, G.; Ovsyannikov, S. V.; Brückel, Thomas; Trots, D. M.; Hosono, H.; Dubrovinsky, L.; Matsuishi, S.; Mittal, R.; Su, Y.

doi:10.1088/1742-6596/377/1/012034

Journal Article

FZJ-2017-06675

Pressure-driven Phase Transition in CaFeAsF at 40 and 300 K

Mishra, S. K. (Corresponding author) ; Mittal, R. ; Chaplot, S. L. ; Ovsyannikov, S. V. ; Trots, D. M. ; Dubrovinsky, L. ; Su, Y.FZJ* ; Matsuishi, S. ; Hosono, H. ; Garbarino, G. ; Brückel, T.FZJ*

2012
IOP Publ. Bristol

Journal of physics / Conference Series 377, 012034 - (2012) [10.1088/1742-6596/377/1/012034]

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Please use a persistent id in citations: http://hdl.handle.net/2128/15320 doi:10.1088/1742-6596/377/1/012034

Abstract: We carried out systematic investigation of high pressure crystal structure and structural phase transition upto 46 GPa at 40 K and 25 GPa at 300 K in CaFeAsF using powder synchrotron x-ray diffraction experiments. Rietveld analysis of the diffraction data at 40 K reveals a structural phase transition from an orthorhombic to a monoclinic phase at Pc = 13.7 GPa, while increasing pressure. The transition to a lower symmetry phase (orthorhombic to monoclinic) in this 1111 compound under pressure is in contrast with the transition to a high symmetry phase (orthorhombic to tetragonal) as observed in the '122' type compounds. On heating from 40 K at high pressure, CaFeAsF undergoes a monoclinic to tetragonal phase transition around 25 GPa and 200 K. Further, it does not show any post-tetragonal phase transition, as observed in '122' compounds (CaFe2As2, BaFe2As2), and remains in the tetragonal phase upto 25 GPa at 300 K. The dPc/dT slope is found to be positive for CaFeAsF and CaFe2As2, unlike a negative gradient was found in case of BaFe2As2.

Keyword(s): Magnetic Materials (1st) ; Magnetism (2nd)

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