The direct current (dc) electrical conductivity of the conducting polymer Versicon TM blended in poly(vinyl chloride) (PVC) was measured from 25 K to 310 K. The data were fitted to various electrical transport models, and the best fit was found with the fluctuation-induced tunneling model, suggesting that tunneling dominates in the mode of electron transport at low temperatures. The parameters, T 1 and T 0 from the fluctuation-induced tunneling model, were found to be 625 K and 129 K, respectively. The interparticle distance was estimated to be about 13Å. At higher temperatures, the plot of the log of resistivity versus the reciprocal of the temperature was linear, indicating that thermally activated hopping dominated the mode of electrical transport at these temperatures. The results support earlier findings that Versicon TM forms continuous aggregates in blends. The results also support growing evidence in the literature that these types of aggregate formation tend to strongly influence the mode of electrical transport in composites.Versicon TM , a product of Allied Signal Inc., is a polyaniline doped with an organic sulfonic acid. 1 When Versicon TM is dispersed in poly(vinyl chloride) (PVC) and other thermoplastics, it is reported to have a tendency to aggregate spontaneously to form conducting pathways throughout the system. The Versicon TM particles are spherical and range in size from 20 to 100 mm, but can be broken down into submicron particles in blends. 1 Work done in our laboratory confirmed that even pressed pellets of Versicon TM behaved like they consisted of aggregates of spherical particles. 2 Versicon TM in blends such as PVC is reported to be useful for electrical shielding and other specific applications such as for loadings in conductive paints. 1 This study is to explore the mode of electrical transport in Versicon TM in blends with highly resistive media such as PVC.Blends of 10%, 20%, and 30% Versicon TM in PVC were supplied by Americhem in the form of grains about two millimeters in size. The samples were heat pressed at about 200 ± C. Only the 30% Versicon TM blend was used in our measurements since the 20% and 10% samples were practically insulators. A sample of the 30% Versicon TM blend was cut into a parallelepiped (14.6 3 2.1 3 1.0 mm) for the resistivity measurements. The four lead method was used in the I-V measurements. Silver paint was used to attach leads to the sample. The data acquisition system consisted of Keithley Model 196 Digital Multimeter, a Keithley a) Author to whom all correspondence should be addressed.Model 220 Current Source, a Keithley Model 705 Scanner to allow the sample circuits and a test circuit to be opened and closed, a Lake Shore Cryotronics Model 330 Autotuning Temperature Controller which sets and reads the temperature at the sample site, and a CTI-Cryogenices 22C/350C Cryodyne © closed cycle helium refrigerator from Janis Research. An IEEE 488 interface from Capital Equipment Corporation enabled these devices to be controlled and the data to be collecte...

D.C. electrical transport measurements have been done over the temperature range 200 K. to 450 K on the mixed conductor Cu3.0CS2 This work extends the original work done on CuxCS2 over the temperature range 260 K to 350 K. Above 220 K, the voltage versus time curves follow the Yokota model for mixed conductors. Below 220K, the voltage versus time curves were practically constant, suggesting very little ionic transport below this temperature, and an electronic conductivity of the order of 10−5 (Ω cm)−1 at 200 K. At ambient temperatures, the ionic conductivity and electronic conductivity were both of the order of 10−3 (Ω cm)−1, and the chemical diffusion coefficient found to be of the order of 10−6 cm2s−1, in agreement with earlier work on Cu3CS2. Above 220 K, the ionic conductivity versus temperature plots were of the Arrhenius form with an activation energy of about 0.36 eV. The jump time and residence time were estimated to be of the order of 10−12s and 10−6s respectively, confirming hopping as the mode of ionic transport. The electronic conductivity versus temperature plot confirmed thermal activation as the mode of electronic transport. The results suggest CuxCS2 to be very stable and the Yokota model, with very little modification, to be very reliable for the analysis of these mixed conductors.

Ag 3.0 CS 2 is one of a family of amorphous mixed ionic electronic conductors A x CS 2 ͑A ϭ Cu, Ag, and x between 2.8 and 4.0͒. This work extends the electrical transport measurements over a temperature range 170 to 440 K. Direct current four-probe transient methods were used to acquire voltage vs. time profiles of the material, and the ionic and electronic conductivities, and the chemical diffusion coefficients obtained following Yokota's model for mixed conductors. Differential scanning calorimetry showed phase transitions at about 411 and 451 K. Variations in the electrical transport measurements at around 400 K seem to corroborate the first phase transition. Thermogravimetric analysis shows no decomposition of the material up to about 600 K. The ionic conductivity over the entire temperature range is of the Arrhenius form, supporting hopping as the mode of ionic transport, with an activation energy of about 0.25 eV, and jump and residence times of the order of 10 Ϫ12 and 10 Ϫ8 s, respectively. The electronic conductivity results suggest possible variable range hopping between localized states, in support of earlier results obtained from the estimate of the electronic diffusion. The chemical diffusion coefficients were also of the Arrhenius form, with an activation energy of about 0.24 eV.