Abstract
Ytterbium silicide-based thermoelectric materials have attracted attention because they exhibit large power factor owing to large absolute values of their Seebeck coefficient as well as high electrical conductivity. In this study, in order to figure out the reason that ytterbium silicides exhibit such high power factor, we synthesized Yb1-xLuxSi2 and characterized the Yb valence and the Seebeck coefficients as a function of temperature from 20K to 300K. The Yb valences in Yb1-xLuxSi2 estimated by XAFS spectrum indicated mixed valences with 2.7 and 2.8 for x＝0.0 and 0.5, respectively. The minimum value of the Seebeck coefficient was －57.6 µVK－1 at 127K, which could be caused by a f- electron contribution due to the mixed valence.
