1 research outputs found
Pressure-Induced Phase Transitions and Correlation between Structure and Superconductivity in Iron-Based Superconductor Ce(O<sub>0.84</sub>F<sub>0.16</sub>)FeAs
High-pressure angle-dispersive X-ray
diffraction experiments on iron-based superconductor CeÂ(O<sub>0.84</sub>F<sub>0.16</sub>)ÂFeAs were performed up to 54.9 GPa at room temperature.
A tetragonal to tetragonal isostructural phase transition starts at
about 13.9 GPa, and a new high-pressure phase has been found above
33.8 GPa. At pressures above 19.9 GPa, CeÂ(O<sub>0.84</sub>F<sub>0.16</sub>)ÂFeAs completely transforms to a high-pressure tetragonal phase,
which remains in the same tetragonal structure with a larger <i>a</i>-axis and smaller <i>c</i>-axis than those of
the low-pressure tetragonal phase. The structure analysis shows a
discontinuity in the pressure dependences of the Fe–As and
Ce–(O, F) bond distances, as well as the As–Fe–As
and Ce–(O, F)–Ce bond angles in the transition region,
which correlates with the change in <i>T</i><sub>c</sub> of this compound upon compression. The isostructural phase transition
in CeÂ(O<sub>0.84</sub>F<sub>0.16</sub>)ÂFeAs leads to a drastic drop
in the superconducting transition temperature <i>T</i><sub>c</sub> and restricts the superconductivity at low temperature. For
the 1111-type iron-based superconductors, the structure evolution
and following superconductivity changes under compression are related
to the radius of lanthanide cations in the charge reservoir layer