Lattice dynamics of the transition metal pentatellurides ZrTe5 and HfTe5

Fresh Raman data collected from the (001) face of a ZrTe₅ single crystal and from polycrystalline powders of ZrTe₅ and HfTe₅ are presented. A simple model assuming only central interactions between nearest neighbour atoms is used for lattice dynamical calculations at $\text{k}\text{=}\text{0}$. The model accounts for the observations and places emphasis on the virtually lacking dynamical coupling between the two basic structural units in these pentatellurides trigonal-prismatic (MTe₃)_n rods and zig-zag (Te₂)₂ chains].