Lattice dynamics study of the structural transition in IrTe2

In this work, we perform a systematic study of the lattice dynamics of IrTe using temperature dependence of X-ray diffraction experiment. It is found that the lattice structural symmetry of IrTe changes from trigonal (space group ) into monoclinic () below the phase transition temperature (). Remarkably, experimental results show that the trigonal cell still insists below , which coexists intrinsically with the monoclinic cell. After the phase transition, the proportion of the monoclinic cell almost remains unchanged. The structure phase transition temperatures determined from cooling and warming are 240 K and 265 K, respectively. Moreover, the superlattice phase is found with 13.5 , which is suggested to be caused by the destabilization of polymeric Te–Te bonds.