Grain Size Effect on the Figure of Merit of Sintered Solid Solutions Based on Bi2Te3

Abstract

The dependence of the thermoelectric figure of merit Z on grain size in sintered 16% Bi2Se3‐84% Bi2Te3 and 75% Sb2Te3‐25% Bi2Te3 solid solutions is analysed. In n‐type materials, due to the carrier density dependence on the specific surface, the maximum moves towards large grain sizes when doping increases. In p‐type materials, the changes of Z with grain size are smaller than in n‐type materials.

Effect of grain size on thermoelectric properties of n-type nanocrystalline bismuth-telluride based thin films

“…͑2͒ Figure 5 shows a comparison of the lattice thermal conductivity of the nanocrystalline thin films with the reported experimental results and the calculated thermal conductivity as given in Table III. 22 For comparison, we have included experimental results on hot-pressed Bi 2 Te 3 based bulk alloys fabricated by Kim and Mitani 23 and Jaklovszky et al 24 and a Bi 2.0 Te 2.7 Se 0.3 hot-pressed bulk alloy from our previous study. 12 We calculate the lattice thermal conductivities along the c-axis and the basal plane ͑a-b-axis͒.…”

The Impact of Nanostructuring on the Thermal Conductivity of Thermoelectric CoSb3

“…Parrott [15] proposed that such a model be operative in the fine-grained sintered semiconductor alloys, and predicted a decrease of about 25 % in the thermal conductivity of Ge±Si alloys as the grain size was reduced to about 4 lm. Further studies on Ge± Si alloys, [12,13,16] lead-telluride based alloys, [17] and bismuth tellurides [18] gave experimental support to the concept that k may be substantially reduced by increasing the number of grain boundaries. The thermal conductivity of CoSb 3 single crystals is about 10 W m ±1 K ±1 at 293 K, and it can be expected that fine grained CoSb 3 materials could have lower k. There are several studies of the grain-size effects on the transport properties of micrometer-size polycrystalline CoSb 3 .…”

Thermoelectric properties of fine-grained Bi2Te3 alloys

“…In the bulk samples of Bi-Te based alloys, however, little has been reported on the grain size effect on the thermoelectric properties of fine-grained samples. In 1975, Jaklovszky et al [12] investigated the lattice thermal conductivity of polycrystalline Bi 2 Te 3 alloys, with a controlled grain size between 15 and 325 m. It has been reported that the lattice thermal conductivity is reduced by 40% over crystalline Bi 2 Te 3 with a grain size of 15 m, and is decreased with decreasing grain size. Green powders of Bi-Te based alloys, in general, have been almost exclusively obtained through conventional melt technique followed by pulverization of the ingot.…”