Structural and Electrical Properties of Solid Polymeric Carbon Disulphide

Abstract

It is known that liquid CS₂ when subjected to high pressure forms a stable solid polymer. Our studies revealed the existence of two distinct forms designated here A and B. Chemical evidence suggests that type A has the composition CS₂ and contains no free sulphur, while type B does contain free sulphur and may be a sub‐sulphide. Infrared structural studies suggest that type A has a highly conjugated polymeric chain structure. X‐ray evidence suggests absence of long range order in both the A and B materials. The dc resistivity of type A is about 10¹³ Ωcm at 300 °K with an activation energy of 0.7 eV and that of type B is about 10³ Ωcm with about 0.02 eV activation energy. The resistivity of both is strongly pressure dependent. Both types show strong frequency dependence of conductivity and permittivity with a region of σ ∼ f² at high frequencies and saturating at 10⁹ and 10¹⁰ Hz, respectively. Although it is impossible to prove that the observed ac data are not related to some form of Maxwell‐Wagner mechanism, it is pointed out that, at least in the case of the A material, the pressure, frequency, and temperature dependences of resistivity are more likely to be associated with two processes in which partially localized electrons hop within chains at high frequencies and between chains at lower frequencies.