A Re-examination of the Crystal Structure of CuFeSe2.

Conflicting reports have appeared in the literature concerning the crystal structure of CuFeSe₂, a I III VI₂ semiconducting compound. In a recent study, based on X-ray and neutron powder diffraction data, it has been reported that the crystal structure of CuFeSe₂ is tetragonal with space group P4̂ m2 (No.115), unit cell parameters a=3.902(1) and c=5.523(4)Å, and Z=1. However, previous single crystal X-ray diffraction studies showed that this material crystallizes in the tetragonal space group P4̂2c (No. 112) with a=5.530(1), c=11.049(2)Å and Z=4. As an attempt to sort out these differences, a reexamination of the crystal structure of CuFeSe₂ carried out using a single-crystal X-ray diffraction technique is discussed in this contribution.