Polycrystalline samples of Cu3TaIn3Se7 and CuTa2InTe4 were synthesized by the usual melt and anneal technique. X‐ray powder diffraction showed a single phase behavior for both samples with tetragonal symmetry and unit cell parameter values a = 5.794 ± 0.002 Å, c = 11.66 ± 0.01 Å, c /a = 2.01, V = 391 ± 1 Å3 and a = 6.193 ± 0.001 Å, c = 12.400 ± 0.002 Å, c /a = 2.00, V = 475 ± 1 Å3, respectively. Differential thermal analysis (DTA) measurements suggested a complicated behavior near the melting point with several thermal transitions observed in the heating and cooling runs. From the shape of the DTA peaks it was deduced that the melting is incongruent for both materials. Magnetic susceptibility measurements (zero‐field cooling and field cooling) indicated an antiferromagnetic character with transition temperatures of T = 70 K (Cu3TaIn3Se7) and 42 K (CuTa2InTe4). A spin–glass transition was observed in Cu3TaIn3Se7 with Tf ≈ 50 K. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Polycrystalline samples of quaternary (Cu–III–Se2)1–x (NbSe)x alloys (III: Ga, In) with x = 1/2 (nominally CuNbGaSe3 and CuNbInSe3) were prepared by the usual melt and anneal technique. The analysis showed a large solubility of Nb in the ternary structures. The unit cell parameters of CuNbGaSe3 (a = 5.617 ± 0.001 Å; c = 11.024 ± 0.003 Å; c /a = 2.02; V = 348 ± 1 Å3) and CuNbInSe3 (a = 5.779 ± 0.001 Å; c = 11.620 ± 0.003 Å; c /a = 2.01; V = 388 ± 1 Å3) were very close to those of the respective ternaries, CuGaSe2 and CuInSe2. Nevertheless, indexation of the diffraction pattern of CuNbGaSe3 suggested, for this alloy, a space group transition from I$ \bar 4 $2d to P$ \bar 4 $2c analogous to CuFeInSe3, recently reported. From DTA measurements it was found that CuNbGaSe3 and CuNbInSe3 are ordered samples with order–disorder transition temperatures of ∼976 K and ∼910 K, and melted incongruently at ∼1185 K and ∼1046 K, respectively. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)