THERMOELECTRIC PROPERTIES OF THE HOT-PRESSED (Bi, Sb)_2(Te, Se)_3 ALLOYS

摘要

While the (Bi, Sb)_2(Te, Se)_3 singlecrystals showed p-type conduction for all compositionsof (Bi, Sb)_2Te_3 and a p-n transition at Bi_2(Te_0.7Se_0.3)_3, the hot-pressed (Bi, Sb)_2(Te, Se)_3 alloysexhibited the p-n transition at (Bi_0.33Sb_0.67)_2Te_3and n-type conduction for all compositions of Bi_2(Te,Se)_3. Compared to the single crystals, the hot-pressed(Bi,Sb)_2(Te, Se)_3 alloys have inherently higherdonor concentration at the same composition due to thesurface oxidation and mechanical deformation of thepowders. For the hot-pressed alloys in the undopedstate, the highest figure-of –merits of 3.07x10~(-3)/Kas p-type and 1.92x10~(-3)/K as n-type were obtainedat the compositions of (Bi_0.2Sb_0.8)_2Te_3 andBi_2(Te_0.85Se_0.15)_3, respectively.