Metallic temperature dependence of microscopic electrical conductivity in HCL-doped polyaniline studied by ESR

Summary form only given. Chemically prepared ES-I powder protonated by HCI was investigated by ESR at temperatures between 4.2 and 300 K and frequencies between 30 and 24,000 MHz.* The frequency dependence of the line width is typical quasi-one-dimensional and is analyzed by a least square fitting to obtain the diffusion rate along the chain D/sub /// and across the chain D/spl perp/, The obtained D/sub ///, indicates a remarkable temperature dependence as follows; (1) above 150 K it is metallic with a power law T/sup -n/, n/spl ap/2~3, (2) below 150 K it abruptly turned to semiconducting with a curious dependence of D/sub //Xexp/(aT) or 1/log(T) or T/sub I/2/ within the large scattering of the data, (3) the diffusion rates show fairly large anisotropy up to 10/sup 5/ at 150 K and 10/sup 3/ at 300 K in the ratio of D//// / D/spl perp/ and (4) a good proportionality of D//// to the dc conductivity /sub spl sigma/ was reconfirmed. The diffusion rates can be transformed to the microscopic electrical conductivity with a relation /spl sigma/sub ///=e/sup 2/N(E/sub F/)D/sub ////c/////sup2/ and yield an estimate of the microscopic conductivity as /spl sigma//spl ges/10/sup 3/ S/crn at 300 K with somewhat large uncertainty which comes from estimation of parameters. This value is consistent with a recent estimation in CSA-doped PANI by Reghu et al.