Transport Measurements in the Mixed IonElectron Conductor Copper(x) CarbonDisulfide
Abstract
(sigma)(,i), (sigma)(,e), and the chemical diffusion coefficient, (')D, of highlydisordered Cu(,x)CS(,2) were investigated using a dc 4lead technique employing Pt electrodes. The experiments were performed at various copper concentrations from x = 2.87 to 3.60 and various temperatures from 260 K to 350 K. The results were interpreted by Yokota's and ionic hopping diffusion theories. (sigma)(,i) and (sigma)(,e) are comparable at room temperature, 4.18 x 10('3) (OMEGA)('1)cm('1) and 1.55 x 10('3) (OMEGA)('1)cm('1) respectively at X = 3.60 and 300 K. Both (sigma)(,i) and (sigma)(,e) follow a simple Arrhenius form with activation energies (TURN)0.40 eV and (TURN)0.29 eV respectively. The exponential dependence of (sigma)(,i) on X is explained in terms of the activation entropy associated with the motion of ions. Electronic conduction is by hopping. Results show that it is reasonable to assume that all the copper ions are mobile. The mobility and the diffusivity of copper ions were found to be 0.71 x 10('6) cm('2)V(' 1)sec('1) and 1.83 x 10('8) cm('2)/sec respectively at X = 3.6 and 300 K. The diffusivity is much less than the chemical diffusion coefficient evaluated from the diffusion time constant, (')D = 0.829 x 10('5) cm('2)/sec at X = 3.60 and 300 K. This is because of a large enhancement factor W (TURN) 453, or a large (PARDIFF)m(,e)/(PARDIFF)N. The change in galvanic cell potential E with X, (PARDIFF)E/(PAR DIFF)X, calculated from the measurements of (sigma)(,i), (sigma)(,e), and (')D, is 14 Volt.
 Publication:

Ph.D. Thesis
 Pub Date:
 1986
 Bibcode:
 1986PhDT........67K
 Keywords:

 Physics: Condensed Matter