TaFe1.14Te3, A New Low-Dimensional Ternary Tantalum Telluride

TaFe1.14Te3 is obtained from the elements in sealed quartz ampoules at 600°C. It crystallizes in the monoclinic space group P21/m with a = 7.4262(8), b = 3.6374(5), c = 9.9925(5) Å, and β = 109.166(8)°. The structure is built up from TaFeTe3 layers. Fe atoms with fractional occupancy are situated at the Te surfaces of the TaFeTe3 slabs giving rise to a 3 D connectivity of the TaFeTe3 layers in space. TaFe1.14Te3 exhibits metallic properties and shows an antiferromagnetic ordering at 215 K. Tight-binding band structure calculations show that Fe–Fe and Ta–Fe interactions are important for the electronic stability of TaFe1.14Te3; replacing Fe by more electron-rich transition metals such as Co or Ni may lead to compounds of composition TaM2Te3. A possible structure is derived from that of TaFe1.14Te3 by filling tetrahedral voids within the TaMTe3 layers with additional 3d metal atoms.