Extended D.C. electrical transport measurements on the mixed conductor Cu_3CS_2

摘要

D.C. electrical transport measurements have been done over the temperautre range 200 K to 450 K on the mixed conductor Cu_(3.0)CS_2. This work extends the original work done on Cu_xCS_2 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) ( OMEGA cm)~(-1) at 200 K. At ambient temperatures, the ionic conductivity and electronic conductivity were both of the order of 10~(-3) ( OMEGA cm)~(-1), and the chemical diffusion coefficient found to be of the order of 10~(-6) cm~2s~(-1), in agreement with earlier work on Cu_3CS_2. 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~(-12)s and 10~(-6)s 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 Cu_xCS_2 to be very stable and the Yokota mode, with very little modification, to be very reliable for the analysis of these mixed conductors.