High temperature thermoelectric properties of B12 icosahedral cluster-containing rare earth boride crystals -: art. no. 093703

B-12 icosahedral cluster-containing rare earth boride TbB44Si2, ErB44Si2, YbB44Si2 crystals were grown by the floating zone method and their high temperature thermoelectric properties (Seebeck coefficient, resistivity) measured. REB44Si2 is isostructural to the magnetic TbB50 compound. These compounds are attractive as high temperature materials due to their stability. An ErB66 crystal was also measured for comparison. Seebeck coefficients exceeding 200 mu V/K are observed at temperatures above 1000 K for the REB44Si2 compounds and the conductivity increases rapidly as temperature is increased through the variable range hopping mechanism. REB44Si2 compounds were found to have a larger power factor compared to ErB66. The thermal conductivity of ErB44Si2 was also measured and determined to take the low value of 0.027 W/cm/K at room temperature. (C) 2005 American Institute of Physics.