(Nb,Ta)_9(S,Te)_5, a Metal-Rich Chalcogenide with a Microporous Metal Substructure

摘要

Niobium and tantalum form several metal-rich chalcogenides of complex structure. Compounds such as Nb_(21)S_8, Nb_5Se_4 or Ta_6S) have been known for many years: others such as Ta_6S (triclinic), Ta_3S_2. Ta_2Se, Nb_(4.7)Te_5, Ta_2Te_3, and Ta_6Te_5have been characterized very recently. A striking feature of these compounds is the structural heterogeneity which, as a matter of fact, is not only due to variation in composition.