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Graphene-assisted synergistic electronic DOS modulation and phonon scattering to improve the thermoelectric performance of Mg3Sb2-based materials.
- Source :
- Journal of Materials Chemistry A; 9/21/2023, Vol. 11 Issue 35, p18811-18819, 9p
- Publication Year :
- 2023
-
Abstract
- Grain boundary (GB) scattering has been widely reckoned as a primary restraint on room-temperature (RT) carrier mobility in Mg<subscript>3</subscript>Sb<subscript>2</subscript>-based materials. In this work, two-dimensional graphene (G) with varied contents was added to single phase Mg<subscript>3.24</subscript>Sb<subscript>1.5</subscript>Bi<subscript>0.49</subscript>Te<subscript>0.01</subscript> materials in order to tailor the highly resistive space-charge region at GBs. The results indicate that introducing G effectively lowers the carrier transport energy barrier E<subscript>b</subscript> from 42 meV (pristine sample) to 18 meV (Mg<subscript>3.24</subscript>Sb<subscript>1.5</subscript>Bi<subscript>0.49</subscript>Te<subscript>0.01</subscript>/1.0 vol% G sample), and correspondingly increases the drift mobility by 112.5% from 32 cm<superscript>2</superscript> V<superscript>−1</superscript> s<superscript>−1</superscript> to 68 cm<superscript>2</superscript> V<superscript>−1</superscript> s<superscript>−1</superscript> at RT, leading to an enhanced power factor and thus ZT value. Besides, first-principles calculations were also performed to qualitatively bridge the underlying negative correlation between the electronic density of states (DOS) and GB potential barrier E<subscript>b</subscript>. Moreover, the equivalent nano-particle phonon scattering is also realized through introducing the two-dimensional G, contributing to a moderate reduction in lattice thermal conductivity as quantitatively illustrated based on the Debye–Callaway model. Consequently, the figure of merit ZT for G-added samples is greatly improved in the entire temperature range compared with that of the G-free sample. This study opens up a new avenue for rationally engineering the grain boundary, via regulating interfacial electronic DOS, to optimize electrical transport properties and ZT values. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 20507488
- Volume :
- 11
- Issue :
- 35
- Database :
- Complementary Index
- Journal :
- Journal of Materials Chemistry A
- Publication Type :
- Academic Journal
- Accession number :
- 171899955
- Full Text :
- https://doi.org/10.1039/d3ta02431h