New Compounds with Cobaltite Structure

Abstract

CoAsS is known to exist in the form of the mineral cobaltite. Its structure and the total number of valence electrons of its components are the same as those of iron pyrite (FeS₂). It was to be expected, therefore, that the electronic configuration of cobalt in cobaltite should be the same as that of iron, in pyrite, so that, like pyrite, cobaltite should also exhibit semiconducting properties. This expectation has since been substantiated by electrical measurements¹. Two similar compounds, NiAsS and NiSbS, are also known to exist as minerals (gersdorffite and ullmannite respectively). They also have a pyrite-type of structure, but the number of their valence electrons corresponds to that of the metallic pyrite phase CoS₂, that is to say they contain one unpaired electron which makes them metallic.