Pressure-induced reversible amorphization in superconducting compound FeSe_0.5Te_0.5

Abstract

We report pressure-induced amorphization phenomenon in a superconducting compound FeSe_0.5Te_0.5 to a pressure of 27 GPa in a diamond anvil cell. The synchrotron x-ray diffraction studies reveal that the ambient pressure tetragonal phase (space group P4/nmm) transforms to an amorphous phase at 11.5 GPa during compression and reverts back to the tetragonal phase during decompression at 2.8 GPa. The measured equation of state for the tetragonal phase and the amorphous phase is presented. The disordering of Fe(SeTe)₄ tetrahedra under compression is attributed to a kinetic hindrance to a stable phase and is likely to impact its superconducting properties under high pressures.

Keywords:

• amorphization
• high pressure
• superconductor

Acknowledgements

We acknowledge support from the National Science Foundation (NSF), Division of Materials Research (DMR), under Grant No. DMR – 0703891. Andrew Stemshorn acknowledges support from the Carnegie/DOE Alliance Center (CDAC) under Grant No. DE-FC52-08NA28554. Portions of this work were performed at HPCAT (Sector 16), Advanced Photon Source (APS), Argonne National Laboratory.