Tetragonal To Collapsed Tetragonal Phase Transition In BaFe{sub 2}As{sub 2} and CaFe{sub 2}As{sub 2}

Journal Article · Wed Dec 01 00:00:00 EST 2010 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.3530541· OSTI ID:21509970

Mittal, R; Mishra, S K; Chaplot, S L ^[1]; Ovsyannikov, S V; Trots, D M; Dubrovinsky, L ^[2]; Greenberg, E ^[2]; Su, Y ^[3]; Brueckel, Th ^[3]; Matsuishi, S; Hosono, H ^[4]; Garbarino, G ^[5]

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1. Solid State Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India)
2. Bayerisches Geoinstitut, University Bayreuth, D-95440 Bayreuth (Germany)
3. Juelich Centre for Neutron Science, IFF, Forschungszentrum Juelich, Outstation at FRM II, Lichtenbergstr. 1, D-85747 Garching (Germany)
4. Frontier Research Center, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503 (Japan)
5. European Synchrotron Radiation Facility, BP 220, 38043 Grenoble (France)

Superconductivity in MFe{sub 2}As{sub 2} (M = Ba, Ca) compounds appears either at a critical doping level at ambient pressure or in the parent compound itself by application of pressure above a critical value. We report high pressure powder x-ray diffractions studies for these compounds at 300 K up to about 56 GPa using membrane diamond anvil cells. The measurements for BaFe{sub 2}As{sub 2} show a new tetragonal to collapsed tetragonal phase transition at about 22 GPa that remains stable upto 56 GPa. CaFe{sub 2}As{sub 2} is already known to transform to collapsed phase at 1.7 GPa at 300 K. Our measurements on CaFe{sub 2}As{sub 2} do not show any post collapsed phase transition on increase of pressure 50 GPa at 300 K. It is important to note that the transition in both compounds occurs when they are compressed to almost the same value of the unit cell volume and attain similar c{sub t}/a{sub t} ratios. We present a detailed analysis of the pressure dependence and structure phase transitions as well as equation of state in these important FeAs compounds that should be useful in the context of possible superconductivity in the collapsed phase.

• OSTI ID: 21509970
• Journal Information: AIP Conference Proceedings, Vol. 1313, Issue 1; Conference: PEFM-2010: International conference on physics of emerging functional materials, Mumbai (India), 22-24 Sep 2010; Other Information: DOI: 10.1063/1.3530541; (c) 2010 American Institute of Physics; ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BARIUM COMPOUNDS
CALCIUM COMPOUNDS
CRYSTAL-PHASE TRANSFORMATIONS
DIAMONDS
EQUATIONS OF STATE
IRON ARSENIDES
MEMBRANES
POWDERS
PRESSURE DEPENDENCE
PRESSURE RANGE GIGA PA
SUPERCONDUCTIVITY
SUPERCONDUCTORS
X-RAY DIFFRACTION
ALKALINE EARTH METAL COMPOUNDS
ARSENIC COMPOUNDS
ARSENIDES
CARBON
COHERENT SCATTERING
DIFFRACTION
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELEMENTS
EQUATIONS
IRON COMPOUNDS
MINERALS
NONMETALS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
PNICTIDES
PRESSURE RANGE
SCATTERING
TRANSITION ELEMENT COMPOUNDS