Influence of Bi on topological self-organization in arsenic and germanium selenide networks

Abstract

The influence of Bi on the network structure of Ge₂₀Se_80−yBi_y and As_40−ySe₆₀Bi_y glasses is investigated by high-resolution X-ray photoelectron spectroscopy (XPS). The results show that Bi enters the glass network of both Ge–Se and As–Se glass systems in the form of BiSe_3/2 pyramids, with a significant increase in the concentration of homopolar Ge–Ge and As–As bonds, respectively, compared to Bi-free samples. In these compositions, topological self-organization is found to play a minor role in comparison to phase separation tendencies at the nanoscale caused by Bi addition. It is suggested that BiSe_3/2 rich regions occur as partially ordered nano-thin sheets, which may account for the percolative-type response of electrical conductivity observed in similar Bi containing systems.