Density, differential thermal analysis and direct-current conductivity of Sb₁₀S_{90 −x} Ge _x chalcogenide glasses

Abstract

The glass-transition temperature,T _g, and the crystallization temperature,T _c for glassy Sb₁₀S_{90 −x} Ge _x samples were increased by increasing the Ge content. This was attributed to the closeness of the network by bridging Sb and/or S atoms with additional Ge atoms to form harder Ge–Sb and/or Ge–S bonds. The direct current (d.c.) electrical conductivity for the system Sb₁₀S_{90 −x} Ge _x shows semiconducting behaviour with increasing temperature. At low temperatures, the conductivity was attributed to a hopping conduction mechanism, while at high temperatures it was due to regular band-type conduction. The activation energy, δE _Σ and the conductivity, Σ₀ were increased at low Ge contents. This may be related to the entrance of Ge atoms into the S–S chains. On the other hand, the increase of the Ge content above 20 at % lead to a conversion of the behaviour of the δE _Σ and Σ₀ from the insulating character of S to the semiconducting character of Ge.