AB2X4 compounds and other new thermoelectric materials studied at JPL

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 5 Wcm 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.