New Semiconducting Arsenopyrite-type Compounds

Abstract

IN a recent paper¹ we reported on semiconductivity in CoSb²-type compounds. The ternary analogues of these polycompounds are formed by the arsenopyrite group. The monoclinic minerals arsenopyrite, FeAsS, and gud-mundite, FeSbS, closely correspond to the mineral safflorite, CoAs₂. They have the same number of valence electrons and we therefore expect their cations to have the same d-electron configuration. In CoAs₂ we have found a magneton number much smaller than that corresponding to one unpaired spin¹. A measurement of the magnetic susceptibility of a natural arsenopyrite crystal (from Altenberg, Silesia, the same on which resistivity measurements were performed earlier²) of unknown purity showed a very similar behaviour (see Table 1).