The texture related anisotropy of thermoelectric properties in bismuth telluride based polycrystalline alloys

Abstract

Large size bismuth telluride based polycrystalline alloys have been prepared to investigate the texture-related anisotropy of thermoelectric properties. X-ray diffraction analysis indicated that the n-type alloy was more easily (001) oriented than the p-type one. Both the electrical and thermal conductivities showed strong anisotropy in the textured samples, while the Seebeck coefficient and the ZT were almost isotropic. However, as the electrical and thermal conductivities were measured along different directions, the ZT could be overestimated up to ∼60%. A relationship between the texture degree and the anisotropy of the thermal conductivity has been proposed.

Enhanced thermoelectric performance in spark plasma textured bulk n-type BiTe2.7Se0.3 and p-type Bi0.5Sb1.5Te3

“…Similar enhancement in the 00l peak intensity in the perpendicular direction is reported in literature. 19 The degree of orientation can be measured in terms of the orientation factor given by…”

“…The values presented here are experimental for SPS samples; however for the SPT samples, due to lack of sufficiently thick samples we have obtained the j ab values from j c measurement. Such a conversion is possible with the results from XRD texture analysis and by using Lotgering method for orientation factor (F) measurements as reported by Shen et al 19 A corrected value of thermal conductivity in the ab-plane was obtained from the plot of j c /j ab against the orientation factor. We have used the same plot used by Shen et al to calculate j c /j ab in present SPT samples.…”

Reduced thermal conductivity by nanoscale intergrowths in perovskite like layered structure La2Ti2O7

“…Bi 2 Te 3 related compounds have a maximum efficiency near room temperature 3 and comparatively low operating temperatures (<200 C), while skutterudites and PbTe are classed as intermediate temperature thermoelectrics (up to 650 C). [4][5][6][7][8] These materials are being used in large scale applications but they have high processing costs 9 and use toxic elements. Most of these materials have zT close to unity, but they are not stable in air due to the oxidation at these temperatures.…”

“…La 2 Ti 2 O 7 possesses a monoclinic unit cell at room temperature with a space group of P2 1 (a ¼ 13.0150 Å , b ¼ 5.5456 Å , c ¼ 7.8170 Å , and b ¼ 98. 6 ). It possesses the basic requirements for low thermal conductivity, such as large atomic mass, crystal anisotropy, and a complex structure with the a)…”

Thermoelectric Properties of n-Type Half-Heusler Compounds Synthesized by the Induction Melting Method

“…The conversion efficiency of a thermoelectric material is related to the dimensionless figure of merit, ZT= α 2 σT/κ, where α, σ, κ, and T are the Seebeck coefficient, electrical conductivity, total thermal conductivity and absolute temperature, respectively. Prior studies on thermoelectric materials have been published with ZT diversity values varying based on different operating temperatures, such as Bi 2 Te 3 for low temperature [4][5][6], PbTe for mid-temperature [7][8][9], Skutterudites and HHs for mid-high temperature [10,11]. HH compounds are known to be relatively stable at high temperature despite their complex compositions.…”