The Effect of Porosity and Milling Induced Defects on the Thermoelectric Properties of p‐Type Bi₂Te₃‐Based Bulks

Abstract

The p-type (Bi,Sb) 2 Te 3 bulks are prepared from ball-milling powders by resistance pressure sintering method and their thermoelectric properties are investigated as a function of ball milling time. Prolonging milling time would introduce more anti-site defects, interaction of vacancies and antisite defect, grain-boundaries and interface defects, leading to lower carrier concentration and mobility. The peak value of ZT ¼ 1.0 is achieved at 300 K for the 5 h sample. When the testing temperature is over 323 K, the ZT value of the 0 h sample is higher than that of the 5 h sample. The effect of porosity on the thermoelectric properties is also investigated by effective medium theory. As the porosity increased, the electrical resistivity increases and the thermal conductivity decrease.

Tilt-structure and high-performance of hierarchical Bi1.5Sb0.5Te3 nanopillar arrays

“…In contrast to Sb 2 Te 3 -based and Bi 2 Te 3 -based materials 12 , 23 – 25 , 27 – 31 , whose S 2 σ values increase or decrease as the temperature increases, the temperature stability of S 2 σ of the hierarchical Bi 1.5 Sb 0.5 Te 3 nanopillar array with a tilt angle of 45° are useful in practical use. It is clearly demonstrated that the hierarchical Bi 1.5 Sb 0.5 Te 3 nanopillar array with a tilt angle of 45° shows a largely enhanced power factor compared with the hierarchical nanopillar array with a tilt angle of 60° or 90° and previous results 29 – 32 . There is no doubt that the tilt architecture significantly aids in achieving high TE properties, especially for the hierarchical nanopillar array with a tilt angle of 45°.…”

Enhanced high‐temperature thermoelectric performance of CdO ceramics with randomly distributed micropores

“…As the porosity increases, the carrier concentration n of these samples decreases from 4.30×10 19 to 1.84×10 18 cm −3 . Similar results were also obtained in other porous TE material . It needs to be mentioned here some indirect effects rather than just the porosity could affect the carrier concentration of the present porous CdO samples.…”

Tailoring Nanoporous Structures in Bi2Te3 Thin Films for Improved Thermoelectric Performance

“…It shows that the ZT values increase with the porosities in the samples B, C, and C′. However, when the porosity increases to ∼11.5% in sample D, both the carrier mobility and κ l decrease dramatically, which could result from the pore boundary scattering effect and the substantial decrease of effective thickness of the cross section, finally leading to a serious deterioration of the ZT value compared with other samples …”

“…However, when the porosity increases to ∼11.5% in sample D, both the carrier mobility and κ l decrease dramatically, which could result from the pore boundary scattering effect and the substantial decrease of effective thickness of the cross section, finally leading to a serious deterioration of the ZT value compared with other samples. 55 Benefiting from the nanoporous structure, a high ZT value of ∼0.67 at room temperature is achieved in sample C′, which is enhanced by ∼60% compared with the dense sample A and could be further improved by optimizing the carrier concentration. 10 It suggests that tuning the porous structure with rational pore characters can scatter phonons with a wide spectrum of wavelengths and significantly reduce κ l .…”