Preparation and interface analyses of a P-type segmented FeSi2 /Bi2Te3 material

P-type segmented FeSi₂/Bi₂Te₃ thermoelectric material has been prepared by the dip coating procedure using Sn₉₅Ag₅ as the bridge material. An apparent Seebeck coefficient of about 225 μV/K is obtained, which is significantly higher than those of both homogeneous materials β-FeSi₂ and Bi₂Te₃ in the same temperature range. The maximum power output of the segmented FeSi₂ /Bi₂Te₃ is approximately 2.5 times that of the monolithic material β-FeSi₂ in the same temperature range. This implies that not only does the segmented material benefit from Bi₂Te₃ at the low temperature side, but it also makes fully use of the characteristics of β-FeSi₂ at high temperature. SEM and EDAX analyses revealed that interdiffusions do to some extent exist in all interfaces. A eutectic mixture could easily be formed since its melting point is lower than the annealing temperature, which trigger the exfoliation in the interface between Sn ₉₅Ag₅ and Bi₂Te₃ under the stress due to the thermal expansion coefficient mismatch of both materials. Although the maximum power output of the material with a Ni layer sandwiched between Sn₉₅Ag₅ and Bi₂Te₃ is a little lower than those of the materials without Ni layer, the thermal stability can be significantly improved