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Collapsed tetragonal phase in Ca(Fe1-xCox)(2)As-2 stabilized by pressure: Structural studies using single-crystal neutron diffraction

Prokes, K.; Ouladdiaf, B.; Harnagea, L.; Wurmehl, S.; Argyriou, Dimitri LU and Buechner, B. (2012) In Physical Review B (Condensed Matter and Materials Physics) 85(10).
Abstract
Ca(Fe1-xCox)(2)As-2 single crystals with concentration x = 0.032, 0.051, and 0.063 were investigated by means of neutron diffraction under hydrostatic pressure. The region of existence of the high-temperature tetragonal, low-temperature orthorhombic, and pressure-induced collapsed tetragonal phases have been determined and the corresponding p-T phase diagrams for the three compositions have been constructed. Structural details of the tetragonal phases at various conditions have been determined. The anomaly marking the orthorhombic-to-tetragonal structural phase transition temperature T-S decreases with increasing Co substitution. Similarly to that, the critical pressure of the tetragonal (or orthorhombic)-to-collapsed-tetragonal transition... (More)
Ca(Fe1-xCox)(2)As-2 single crystals with concentration x = 0.032, 0.051, and 0.063 were investigated by means of neutron diffraction under hydrostatic pressure. The region of existence of the high-temperature tetragonal, low-temperature orthorhombic, and pressure-induced collapsed tetragonal phases have been determined and the corresponding p-T phase diagrams for the three compositions have been constructed. Structural details of the tetragonal phases at various conditions have been determined. The anomaly marking the orthorhombic-to-tetragonal structural phase transition temperature T-S decreases with increasing Co substitution. Similarly to that, the critical pressure of the tetragonal (or orthorhombic)-to-collapsed-tetragonal transition also decreases with increasing Co doping level. The behavior is highly hysteretic and the differences in critical pressures with increasing and decreasing branches eventually makes the collapsed tetragonal phase stable down to ambient pressure and enables structural studies under identical conditions. Within the error bars on the fourth digit, no modification of the As structural positional parameter is found. Such a result suggests that the change of the As-As bond is caused solely by the reduction of the c-axis lattice parameter. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Physical Review B (Condensed Matter and Materials Physics)
volume
85
issue
10
publisher
American Physical Society
external identifiers
  • wos:000302003700001
  • scopus:84859246485
ISSN
1098-0121
DOI
10.1103/PhysRevB.85.104523
language
English
LU publication?
yes
id
1594f033-20e8-40c5-b82a-44b14bbfa4be (old id 2494815)
date added to LUP
2012-05-10 14:33:03
date last changed
2017-01-01 05:38:27
@article{1594f033-20e8-40c5-b82a-44b14bbfa4be,
  abstract     = {Ca(Fe1-xCox)(2)As-2 single crystals with concentration x = 0.032, 0.051, and 0.063 were investigated by means of neutron diffraction under hydrostatic pressure. The region of existence of the high-temperature tetragonal, low-temperature orthorhombic, and pressure-induced collapsed tetragonal phases have been determined and the corresponding p-T phase diagrams for the three compositions have been constructed. Structural details of the tetragonal phases at various conditions have been determined. The anomaly marking the orthorhombic-to-tetragonal structural phase transition temperature T-S decreases with increasing Co substitution. Similarly to that, the critical pressure of the tetragonal (or orthorhombic)-to-collapsed-tetragonal transition also decreases with increasing Co doping level. The behavior is highly hysteretic and the differences in critical pressures with increasing and decreasing branches eventually makes the collapsed tetragonal phase stable down to ambient pressure and enables structural studies under identical conditions. Within the error bars on the fourth digit, no modification of the As structural positional parameter is found. Such a result suggests that the change of the As-As bond is caused solely by the reduction of the c-axis lattice parameter.},
  articleno    = {104523},
  author       = {Prokes, K. and Ouladdiaf, B. and Harnagea, L. and Wurmehl, S. and Argyriou, Dimitri and Buechner, B.},
  issn         = {1098-0121},
  language     = {eng},
  number       = {10},
  publisher    = {American Physical Society},
  series       = {Physical Review B (Condensed Matter and Materials Physics)},
  title        = {Collapsed tetragonal phase in Ca(Fe1-xCox)(2)As-2 stabilized by pressure: Structural studies using single-crystal neutron diffraction},
  url          = {http://dx.doi.org/10.1103/PhysRevB.85.104523},
  volume       = {85},
  year         = {2012},
}