High-Performance Thermoelectric Bulk Colusite by Process Controlled Structural Disordering

Abstract

High-performance thermoelectric bulk sulfide with the colusite structure is achieved by controlling the densification process and forming short-to-medium range structural defects. A simple and powerful way to adjust carrier concentration combined with enhanced phonon scattering through point defects and disordered regions is described. By combining experiments with band structure and phonons calculations, we elucidate, for the first time, the underlying mechanism at the origin of intrinsically low thermal conductivity in colusite samples as well as the effect of S vacancies and antisite defects on the carrier concentration. Our approach provides a controlled and scalable method to engineer high power factors and remarkable figures of merit near the unity in complex bulk sulfide such as CuVSnS colusites.

An Integrated Approach to Thermoelectrics: Combining Phonon Dynamics, Nanoengineering, Novel Materials Development, Module Fabrication, and Metrology

“…[120] Comparisons of the electrical transport properties between higher temperature (1023 and 1073 K) and lower temperature (873 K) sintered samples of Cu 26 V 2 Sn 6 S 32 are shown in Figure 19a-c. [94,117,119] The values of S and ρ for the higher-temperature-sintered sample are larger than those for the lower-temperature-sintered sample. Presumed to have a sulvanite-type structure, the disordered region was first observed in mineral colusite Cu 24.3 V 2.0 (As 5.7 S b 0.6 Fe 0.1 )S 32 .…”

“…[120] Comparisons of the electrical transport properties between higher temperature (1023 and 1073 K) and lower temperature (873 K) sintered samples of Cu 26 V 2 Sn 6 S 32 are shown in Figure 19a-c. [94,117,119] The values of S and ρ for the higher-temperature-sintered sample are larger than those for the lower-temperature-sintered sample. [119] Adv. This is due to the fact that the sulfur vacancies formed through higher temperature sintering reduce p, which decreases from ≈3.26 × 10 21 cm −3 for the 873 K sintered sample to ≈1.35 × 10 21 cm −3 for the 1023 K sintered sample.…”

“…[119] To summarize these results, the low κ lat in colusites is attributed to the disorder regions, structural complexity, and low-frequency vibration. [119] To summarize these results, the low κ lat in colusites is attributed to the disorder regions, structural complexity, and low-frequency vibration.…”

“…Presumed to have a sulvanite-type structure, the disordered region was first observed in mineral colusite Cu 24.3 V 2.0 (As 5.7 S b 0.6 Fe 0.1 )S 32 . [119] Moreover, the disordered regions cause carrier scattering, resulting in reduced µ in the higher-temperature-sintered sample: µ decreases from ≈4.3 cm 2 V −1 s −1 for the 873 K sintered sample to ≈2.1 cm 2 V −1 s −1 for the 1023 K sintered sample. For example, at 670 K, S and ρ increase from ≈90 µV K −1 and ≈12 µΩ m, respectively, for the 873 K sintered sample to ≈220 µV K −1 and ≈100 µΩ m, respectively, for the 1073 K sintered sample (Figure 19a,b).…”

“…At AIST, we have explored the potential of the layered sulfides TiS 2 , [99] (LaS) 1.20 CrS 2 , [129] and (LaS) 1.14 NbS 2 , [100,129] and e,f) [111] images showing the coexistence of ordered and disordered regions within the same crystallite in the sample sintered at 1023 K. Corresponding Fourier-transform patterns are given as insets. [119] Copyright 2018, American Chemical Society www.advancedsciencenews.com and rare-earth elements; T = Ti, V, Cr, Nb, and Ta; X = S, Se; n = 1, 2, and 3; and 0.08 < m < 0.30). Reproduced with permission.…”