Skutterudite structure and thermoelectric property in CefFe8-xCoxSb24 (f=0-2, x=0-8)

The skutterudite structure and thermoelectric properties of CefFe8-xCoxSb24 were investigated by means of X-ray diffraction (XRD) experiments, energy- dispersive X-ray (EDX) measurements under a transmission electron microscop e, and measurements of the thermoelectromotive force. The filling number of Cc into voids in the skutterudite (f) is variable at each substitution num ber of Fe by Co (x) and decreases with increasing x, The four-cornered ring of Sb tends to become square more rapidly with increasing f than with incr easing x. The lattice parameter increases with increasing f; whereas it dec reases with increasing x, The sign of the thermoelectromotive force depends on x for f < 1, although it is always positive for f > 1. The type of semi conductor changes at a critical valence electron density of 194/nm(3). (C) 2000 Elsevier Science Ltd. All rights reserved.