Abstract
Pb1-xSnxTe (0≤x≤0.25) doped with different amount of PbI2 ranging from 0 to 0.4wt% were prepared by stirring melt mixtures and unidirectional solidifying using PbTe and SnTe. The thermal conductivity of the Pb0.75Sn0.25Te doped with 0.04wt% PbI2 reduced to 18.0mW/cmK, which is 18% lower than that of the melt grown PbTe, as a resultant of the reduction of the phonon component κph. The electron density of an n-type Pb0.95Sn0.05Te doped with 0.4wt% of PbI2 decreased along the growth direction from 3.18×1020cm-3 to 2.60×1017cm-3, which confirms FGM structure. The n-type sintered Pb0.95Sn0.05Te specimens were prepared by the hot-pressing technique using the melt-grown ingot. The thermal conductivity of the sintered specimens was 16.4mW/cmK, which was 12% lower than that of an n-type sintered PbTe. It is found that the carrier scattering mechanism of the sintered specimens are remarkably different from that of the melt-grown ones. The resistivity of an n-type melt-grown PbTe had a hysteretic temperature dependence up to 800K due to evaporation of Te and ambient Ar pressure, which indicates that the change of the thermoelectric properties occurs during practical operation.
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