For the purpose of obtaining superior thermoelectric materials, purification of Bi, Te and Bi
2Te
3 has been carried out.
Bismuth is purified by the method of alkali-treatment and zone melting in removing Cu, Ag and Pb.
For the purification of tellurium, vacuum distillation is very efficient to remove Cu, Ag and Pb.
Measured thermoelectric power a and resistivity of purified Bi
2Te
3 were α=235μV•deg
-1, and p=1.16×10
-3Ω•cm respectively.
The influence of addictive impurities on Bi
2Te
3 is examined. Tl, Li, Pb and Cd etc. are p-type and Cu, Ag, Se, Te, halogen and metal-halides etc. are n-type impurities.
The thermoelectric properties of PbTe, Sb
2Te
3, Bi
2Te
3-Sb
2Te
3 and Bi
2Te
3-Bi
2Se
3 solid solution are examined. The result shows that the solid solution of isomorphous compounds is suitable for the thermoelectric material.
By the use of (Bi-Sb)
2Te
3 p-type element and Bi
2(Te-Se)
3 n-type element thermojunctions, the temperature drop of 71.3 deg was attained with a temperature of hot junction of 30°C.
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