Remarkable Improvement of Thermoelectric Figure-of-Merit in SnTe through In Situ-Created Te Nanoinclusions
| Autor: | M. Navaneethan, Ajay Singh, Dinesh K. Aswal, K.N. Meshram, Pritam Sarkar, Ranu Bhatt, Sajid Ahmad, Shovit Bhattacharya, Ranita Basu, Satish Vitta, K. P. Muthe |
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| Rok vydání: | 2020 |
| Předmět: |
Materials science
Condensed matter physics Phonon scattering Phonon Energy Engineering and Power Technology Thermoelectric materials Thermal conductivity Seebeck coefficient Thermoelectric effect Materials Chemistry Electrochemistry Chemical Engineering (miscellaneous) Grain boundary Charge carrier Electrical and Electronic Engineering |
| Zdroj: | ACS Applied Energy Materials. 3:7113-7120 |
| ISSN: | 2574-0962 |
| Popis: | SnTe exhibits very low Seebeck coefficient along with high electrical–thermal conductivities owing to very high hole concentration that results from intrinsic Sn vacancies. All these unfavorable thermoelectric parameters restrict pristine SnTe from becoming an outstanding thermoelectric material. In this work, we demonstrate the improvement in figure-of-merit of SnTe through in situ creation of Te nanoinclusions in the SnTe matrix. We have intentionally added excess Te in stoichiometric Sn/Te (1:1) for the synthesis of SnTe. During solidification of SnTe from the melt, the excess Te in the liquid state gets expelled to the grain boundaries. On further cooling, when Te starts to solidify, it exerts strain in the already solidified SnTe grains and creates extensive structural defects including dislocations, twin boundaries, and subgrain boundaries that scatter phonons of midwavelength. The point defect due to intrinsic Sn vacancies and SnTe/Te grain boundaries respectively scatters phonons of low and high wavelengths. Effective scattering of the entire spectrum of phonons through the hierarchical defects gives rise to an ultralow lattice thermal conductivity of 0.5 W m–1 K–1 that is close to the theoretical minimum limit. The contribution from the heavy hole valence band in transport along with energy filtering of charge carriers at the SnTe/Te interface results in improvement of the Seebeck coefficient near room temperature. The cumulative effect of improved Seebeck coefficient and suppressed thermal conductivity gives rise to a high figure-of-merit (ZT) value of ∼1.5 at 750 K and an average ZT of ∼0.48 for the Sn0.9Te sample. |
| Databáze: | OpenAIRE |
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