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@ARTICLE{Mittal:14216,
author = {Mittal, R. and Mishra, S. K. and Chaplot, S. L. and
Ovsyannikov, S. V. and Greenberg, E. and Trots, D. M. and
Dubrovinsky, L. and Su, Y. and Brückel, T. and Matsuishi,
S. and Hosono, H. and Garbarino, G.},
title = {{A}mbient- and low-temperature synchrotron x-ray
diffraction study of {B}a{F}e2{A}s2 and {C}a{F}e2{A}s2 at
high pressures up to 56 {GP}a},
journal = {Physical review / B},
volume = {83},
number = {5},
issn = {1098-0121},
address = {College Park, Md.},
publisher = {APS},
reportid = {PreJuSER-14216},
pages = {054503},
year = {2011},
note = {R.M. and S.K.M. thank the Department of Science and
Technology (DST), India for providing financial support to
carry out synchrotron x-ray diffraction at European
Synchrotron Radiation Facility, Grenoble, France. We thank
M. Hanfland and W. Crichton for loading the helium into the
cells for our measurements carried out at ESRF.},
abstract = {We report on high-pressure powder synchrotron x-ray
diffraction studies on MFe2As2 (M = Ba, Ca) over a range of
temperatures and pressures up to about 56 GPa using a
membrane diamond-anvil cell. Our data indicate a phase
transition to a collapsed tetragonal phase in both compounds
upon compression. The data at 300 K are measured in both
pressure-increasing and -decreasing cycles. Our measurements
show that at 300 K in the Ba compound, the transition occurs
at 27 GPa, which is much higher than the transition pressure
of 1.7 GPa in the Ca compound. At low temperature, we could
obtain data only in the pressure-increasing cycle, therefore
a precise transition pressure is not identified. At a low
temperature of 33 K, the transition to the tetragonal phase
in the Ba compound starts, upon compression, at about 29
GPa, which is much higher than the transition pressure of
0.3 GPa at 40 K as known in the case of the Ca compound. The
much higher transition pressure in the Ba compound may be
due to its larger unit-cell volume at ambient pressure. 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(t)/a(t) ratios. We
also show that the FeAs4 tetrahedra are much less
compressible and more distorted in the collapsed tetragonal
phase than their nearly regular shape in the ambient
pressure phase. We present a detailed analysis of the
pressure dependence of the structures as well as equations
of state in these important BaFe2As2 and CaFe2As2
compounds.},
keywords = {J (WoSType)},
cin = {PGI-4 / JCNS-1 / Jülich Centre for Neutron Science JCNS
(JCNS) ; JCNS / JARA-FIT / JCNS-2},
ddc = {530},
cid = {I:(DE-Juel1)PGI-4-20110106 / I:(DE-Juel1)JCNS-1-20110106 /
I:(DE-Juel1)JCNS-20121112 / $I:(DE-82)080009_20140620$ /
I:(DE-Juel1)JCNS-2-20110106},
pnm = {Großgeräte für die Forschung mit Photonen, Neutronen und
Ionen (PNI) / Grundlagen für zukünftige
Informationstechnologien},
pid = {G:(DE-Juel1)FUEK415 / G:(DE-Juel1)FUEK412},
shelfmark = {Physics, Condensed Matter},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000287129700008},
doi = {10.1103/PhysRevB.83.054503},
url = {https://juser.fz-juelich.de/record/14216},
}