Thermoelectric Investigation of the Pseudo Binary System PbTe-CoSe2

Composites of nominal composition (Pb0.98Na0.02Te)(1-y) (CoSe2) (y) and (Pb0.95Na0.05Te)(1-y) (CoSe2) (y) with y = 0.05-0.15 have been synthesized to study their thermoelectric properties. In these composites CoTe2 is the secondary phase. The room temperature carrier concentration covers a wide range, 0.5-3.3 x 10(20)/cm(3) depending on the composition. The high-temperature thermoelectric properties are similar to those of Na-doped Pb(Te,Se) alloys. The Seebeck coefficient can be as high as similar to 250 mu V/K when the electrical resistivity is approximately 3.5 m Omega cm. The thermal conductivity of all the composites are very low. The CoTe2 seems to have little effect on the transport properties. The highest ZT achieved is similar to 1.2.