Enhancing Thermoelectric Properties through Control of Nickel Interstitials and Phase Separation in Heusler/Half-Heusler TiNi1.1Sn Composites
| Autor: | Jason E. Douglas, Leo K. Lamontagne, Tresa M. Pollock, Malinda L C Buffon, Francesca Long, Emily E. Levin, Ram Seshadri |
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| Jazyk: | angličtina |
| Rok vydání: | 2018 |
| Předmět: |
Materials science
Heusler 02 engineering and technology TiNiSn TiNi2Sn point defect thermoelectric phonon scattering 01 natural sciences 7. Clean energy lcsh:Technology symbols.namesake Thermal conductivity Phase (matter) Seebeck coefficient 0103 physical sciences Thermoelectric effect General Materials Science lcsh:Microscopy Strengthening mechanisms of materials lcsh:QC120-168.85 010302 applied physics Condensed matter physics Phonon scattering lcsh:QH201-278.5 lcsh:T Fermi level 021001 nanoscience & nanotechnology Thermoelectric materials lcsh:TA1-2040 symbols lcsh:Descriptive and experimental mechanics lcsh:Electrical engineering. Electronics. Nuclear engineering 0210 nano-technology lcsh:Engineering (General). Civil engineering (General) lcsh:TK1-9971 |
| Zdroj: | Materials, Vol 11, Iss 6, p 903 (2018) Materials; Volume 11; Issue 6; Pages: 903 |
| ISSN: | 1996-1944 |
| Popis: | Thermoelectric devices, which allow direct conversion of heat into electrical energy, require materials with improved figures of merit ( z T ) in order to ensure widespread adoption. Several techniques have been proposed to increase the z T of known thermoelectric materials through the reduction of thermal conductivity, including heavy atom substitution, grain size reduction and inclusion of a semicoherent second phase. The goal in these approaches is to reduce thermal conductivity through phonon scattering without modifying the electronic properties. In this work, we demonstrate that Ni interstitials in the half-Heusler thermoelectric TiNiSn can be created and controlled in order to improve physical properties. Ni interstitials in TiNi 1.1 Sn are not thermodynamically stable and, instead, are kinetically trapped using appropriate heat treatments. The Ni interstitials, which act as point defect phonon scattering centers and modify the electronic states near the Fermi level, result in reduced thermal conductivity and enhance the Seebeck coefficient. The best materials tested here, created from controlled heat treatments of TiNi 1.1 Sn samples, display z T = 0.26 at 300 K, the largest value reported for compounds in the Ti–Ni–Sn family. |
| Databáze: | OpenAIRE |
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