Electrical properties of glasses in the GeBiSbSe and GeBiS systems

Measurements of optical absorption, dc conductivity and thermopower were carried out on glasses of the types (GeSe_3.5)₈₈sbPin12?xBi_x. The main results are: 1) observation of n-type conduction in the Ge₂₀Bi_xS_80?x glasses containing high concentrations of Bi; 2) in the mixed doped glasses, transition from p-type for a Sb-doped glass (x = 0) to n-type on addition of Bi at nearly equal concentrations of Sb and Bi. The possible types of bonding of the Bi atoms in the structure and their influence on the electrical behaviour are examined.