Comparisons of the thermoelectric properties of n-type PbTe fabricated with different powder processing methods

Bi-doped n-type PbTe powders were fabricated by mechanical alloying and melting/grinding to compare the thermoelectric properties of the alloys with powder processing methods. Hot pressing of the PbTe powders was conducted at 650/spl deg/C and 750/spl deg/C for 1 hour in vacuum. When measured at temperatures ranging from 25/spl deg/C to 450/spl deg/C, PbTe samples fabricated by mechanical alloying exhibited more negative Seebeck coefficient, higher electrical resistivity and lower thermal conductivity, compared to ones prepared by melting/grinding. The temperature for the maximum figure-of-merit shifted to lower temperature for the specimens fabricated by mechanical alloying. When hot pressed at 650/spl deg/C, 0.3 wt% Bi-doped PbTe fabricated by mechanical alloying and melting/grinding exhibited a maximum figure-of-merit of 1.33/spl times/10/sup -3//K at 200/spl deg/C and 1.07/spl times/10/sup -3//K at 350/spl deg/C, respectively.