Ternary transition metal antimonides and bismuthides with MgAgAs-type and filled NiAs-type structure

The 12 equiatomic ternary compounds NbFeSb, NbCoSb, TaCoSb, TRuSb (T = Ti, Zr, Hf, V, Nb, Ta), NbRhSb, ZrCoBi and ZrNiBi crystallize with the face-centered cubic MgAgAs-type structure. The atom distribution on the three sites of this structure was established through Rietveld refinements of X-ray data for VCoSb, NbFeSb, NbRuSb and ZrCoBi. At 750 degrees C VFeSb is isotypic with MgAgAs and at 850 degrees C it crystallizes with a filled NiAs-type structure. The latter structure was also found for a new modification of VNiSb. Magnetic susceptibility measurements with a SQUID magnetometer indicate Pauli paramagnetism for TiFeSb, NbFeSb, TiCoSb, TiNiSb, VNiSb, TiRuSb, NbRuSb and NbRhSb.