Transport properties of Co/sub 1-x/Fe/sub x/Sb/sub 3/

The role of iron on the cobalt site of the filled skutterudites has yet to be firmly ascertained. To address this question, we prepared a series of samples of the form Co/sub 1-x/Fe/sub x/Sb/sub 3/ with x=0, 0.5, 1, 2, 5 and 10 at% by induction melting. We performed measurements of thermal conductivity, thermopower, resistivity, Hall effect, X-ray diffraction, and magnetization. The presence of iron reduces dramatically the lattice thermal conductivity. Iron doping increases the hole concentration resulting in a concomitant reduction of the room temperature Seebeck coefficient. We also observed phonon drag effects at low temperature. Magnetization studies indicate the development of a paramagnetic state. The subtle role of iron in creating lattice defects will also be discussed.