Single Crystal X‐ray Structure of Cu 3 TaSe 4 and a Comparative Study of Cu 3 MX 4 ( M = V, Nb, Ta; X = S, Se, Te)

Single crystals of Cu 3 TaSe 4 were obtained by chemical vapor transport with iodine as transport agent. Cu 3 TaSe 4 crystallizes in the sulvanite structure type with space group P $\bar{4}$ 3 m and a = 5.6613(3) Å at room temperature. Structure refinements against single‐crystal X‐ray diffraction data result in a Cu–Se distance slightly longer than the Ta–Se distance, whereas previous Rietveld refinements obtained a Cu–Se distance shorter than the Ta–Se distance [G. E. Delgado et al., J. Alloys Comp. 2007 , 439 , 346]. The structural variations of sulvanite type compounds Cu 3 MX 4 ( M = V, Nb, Ta; X = S, Se, Te) are discussed in view of small distortions of Cu X 4 and MX 4 tetrahedra and the atomic valences.