  Kondo insulator like material FeSb2 was found to exhibit colossal Seebeck
coefficient. It would have had huge potential in thermoelectric applications in
cryogenic temperature range if it had not been for the large thermal
conductivity. Here we studied the influence of Te doping at Sb site on thermal
conductivity and thermoelectric effect in high quality single crystals.
Surprisingly, only 5% Te doping suppresses thermal conductivity by two orders
of magnitude, which may be attributed to the substitution disorder. Te doping
also results in transition from an semiconductor to a metal. Consequently
thermoelectric figure of merit (ZT ? 0:05) in Fe(Sb0:9Te0:1)2 at ? 100K was
enhanced by about one order of magnitude when compared to ZT < 0:005 in undoped
FeSb2.
