ABSTRACT Mixing two related transition metal atoms or main group elements can lead to the formation of new pnictides and chalcogenides. This was successfully demonstrated by the Franzen group in the early 90’s with the discovery of a variety of niobium tantalum sulfides forming hitherto unknown structures, namely Nb1.72Ta3.28S2, Nb0.95Ta1.05S, Nb4.92Ta6.08S4, and Nb6.74Ta5.26S4 who all have no isostructural counterpart in either of the binary systems. Nb and Ta atoms occupy the metal atom sites in statistical mixtures in these structures, yet preferences of the Ta atoms for special sites are obvious. Thereafter, the concept of using mixed occupancies of similar, but different transition metal atoms for the synthesis of unprecedented compounds was extended to include germanides, phosphides and antimonides with metal atom pairs like Zr/Ti, Hf/Ti, Zr/Hf, Zr/V, Hf/Nb and Hf/Mo, e.g. in (Hf,Nb)10Ni3P5, (Hf,Mo)2P, (Zr,Ti)5Sb8, (Hf,Ti)7Sb4, and (Zr,V)13Sb10. The very same concept can be applied to mixing the anionic elements, e.g. S and Te atoms on various sites in different ratios, as shown with the uncovery of Ta5(S,Te)2, Ta5(Se,Te)3 and Zr7(Sb, Se)4. |
