Thermoelectric properties of Fe/sub 1-x/Ni/sub x/Sb/sub 3/ ribbons

This paper deals with the microstructures and thermoelectric properties of Fe/sub 1-x/Ni/sub x/Sb/sub 3/ ribbons between x=0 and 1.0. The ribbons were fabricated by casting on a rotating copper roll with the surface velocity of 10 m/s, and then annealed for 3.6 ks at 873 K. The microstructures were investigated by means of X-ray diffraction measurements and transmission electron microscopic observations. The CoAs/sub 3/ type of structure, namely skutterudite structure, appeared as well as the other structures of FeSb/sub 2/, NiSb/sub 2/ and Sb below x=0.45 and above 0.55. Only the skutterudite appeared and the other structures disappeared between x=0.45 and 0.55. The thermoelectromotive force and electrical resistivity were measured under a vacuum from 300 K to 670 K. The thermoelectromotive force was of p-type of semiconductor for x<0.5 and of n-type for x>0.5. The electrical resistivity recorded a maximum at x=0.5. The curve of electrical resistivity versus x was asymmetric at x=0.5. The electrical resistivity was larger for x<0.5 than for x>0.5 at the same deviation from x=0.5. The power factor, which was estimated from the thermoelectromotive force and electrical resistivity, reached to maximums at x=0.4 and x=0.6, and was small at x=0.5 at 300 K.