Transport phenomena in superionic Na (N...) Cu2-N... S (N...=0.05; 0.1; 0.15; 0.2) compounds

摘要

The electronic and ionic conductivity, the electronic and ionic Seebeck coefficients, and the thermal conductivity of Na (x) Cu2 - x S (x = 0.05, 0.1, 0.15, 0.2) compounds were measured in the temperature range of 20-450 A degrees D. The total cationic conductivity of Na0.2Cu1.8S is about 2 S/cm at 400 A degrees D (the activation energy ae 0.21 eV). Over the studied compounds, the composition Na0.2Cu1.8S has the highest electronic conductivity (500-800 S/cm) in the temperature range from 20 to 300 A degrees D, and the highest electronic Seebeck coefficient (about 0.2 mV/K) in the same temperature range is observed for Na0.15Cu1.85S composition; the electronic Seebeck coefficient increases abruptly above 300 A degrees D for all compounds. The thermal conductivity of superionic Na0.2Cu1.8S is low, which causes high values of the dimensionless thermoelectric figure of merit ZT from 0.4 to 1 at temperatures from 150 to 340 A degrees C.