High temperature thermoelectric properties of Ca3Co2O6 single crystals
M. Mikami1, R. Funahashi2
1CREST, Japan Science and Technology Corporation, Ikeda, Osaka 563-8577, Japan
2National Institute of Advanced Industrial Science and Technology, Ikeda, Osaka 563-8577, Japan
Single crystals of quasi-one-dimensional complex oxide Ca3Co2O6 have been grown by a solution method. The average size of the needle-like Ca3Co2O6 crystals was 1x1x10 mm3. Thermoelectric properties in the direction of c-axis were measured at various temperature ranges. While the electrical resistivity is as high as 5Wcm at 300 K, it decreases rapidly with increasing temperature and is 0.03 Wcm at 700 K. The Seebeck coefficient is positive and decreases with increasing temperature from 400 to 140 m V/K in a temperature region of 273-1023 K. Due to the significant reduction of the electrical resistivity at high temperature range, the power factor reaches 1x10-4 W/mK2 at 973 K. The thermal conductivity as well as thermoelectric figure of merit will be presented.