METALLIC TRANSPORT-PROPERTIES IN HCLO4 DOPED POLYACETYLENE - SHIRAKAWA AND HIGHLY-ORIENTED POLYACETYLENES

We have studied the temperature dependence of electrical conductivity for the Shirakawa (S-PA) and highly oriented polyacetylene (HOPA) doped heavily with HClO4. All the samples showed quite a similar temperature dependence with a metallic behaviour at high temperatures between 200 and 300K in spite of their diverse conductivity values at room temperature differing by two orders of magnitude: 280 S/cm for S-PA, while 12000 S/cm for HOPA. The data were fitted to the models consisting of semiconducting resistance (the Sheng model) plus metallic resistance. The point in the fitting is that either T2 dependence or the Kivelson-Heeger type dependence for the metallic resistance could provide a sufficiently acceptable results over the whole temperature ranges measured.