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Title: Enhancement of thermoelectric properties in the Nb–Co–Sn half-Heusler/Heusler system through spontaneous inclusion of a coherent second phase

Abstract

Half-Heusler XYZ compounds with an 18 valence electron count are promising thermoelectric materials, being thermally and chemically stable, deriving from relatively earth-abundant components, and possessing appropriate electrical transport properties. The typical drawback with this family of compounds is their high thermal conductivity. A strategy for reducing thermal conductivity is through the inclusion of secondary phases designed to minimize negative impact on other properties. Here, we achieve this through the addition of excess Co to half-Heusler NbCoSn, which introduces precipitates of a semi-coherent NbCo{sub 2}Sn Heusler phase. A series of NbCo{sub 1+x}Sn materials are characterized here using X-ray and neutron diffraction studies and electron microscopy. Electrical and thermal transport measurements and electronic structure calculations are used to understand property evolution. We find that annealing has an important role to play in determining antisite ordering and properties. Antisite disorder in the as-prepared samples improves thermoelectric performance through the reduction of thermal conductivity, but annealing during the measurement degrades properties to resemble those of the annealed samples. Similar to the more widely studied TiNi{sub 1+x}Sn system, Co addition to the NbCoSn phase results in improved thermoelectric performance through a decrease in thermal conductivity which results in a 20% improvement in the thermoelectric figuremore » of merit, zT.« less

Authors:
; ; ;  [1];  [2];  [3]; ;  [4];  [3];  [2];  [1];  [2];  [2]
  1. Materials Department, University of California, Santa Barbara, California 93106 (United States)
  2. (United States)
  3. Materials Research Laboratory, University of California, Santa Barbara, California 93106 (United States)
  4. Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112 (United States)
Publication Date:
OSTI Identifier:
22598866
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 120; Journal Issue: 7; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ANNEALING; ELECTRON MICROSCOPY; ELECTRONIC STRUCTURE; ELECTRONS; HEUSLER ALLOYS; NEUTRON DIFFRACTION; NEUTRONS; PERFORMANCE; PRECIPITATION; THERMAL CONDUCTIVITY; THERMOELECTRIC MATERIALS; THERMOELECTRIC PROPERTIES; VALENCE; X RADIATION; X-RAY DIFFRACTION

Citation Formats

Buffon, Malinda L. C., E-mail: mandibuffon@mrl.ucsb.edu, Verma, Nisha, Lamontagne, Leo, Pollock, Tresa M., Materials Research Laboratory, University of California, Santa Barbara, California 93106, Laurita, Geneva, Ghadbeigi, Leila, Sparks, Taylor D., Lloyd, Demetrious L., Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, Seshadri, Ram, Materials Research Laboratory, University of California, Santa Barbara, California 93106, and Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106. Enhancement of thermoelectric properties in the Nb–Co–Sn half-Heusler/Heusler system through spontaneous inclusion of a coherent second phase. United States: N. p., 2016. Web. doi:10.1063/1.4961215.
Buffon, Malinda L. C., E-mail: mandibuffon@mrl.ucsb.edu, Verma, Nisha, Lamontagne, Leo, Pollock, Tresa M., Materials Research Laboratory, University of California, Santa Barbara, California 93106, Laurita, Geneva, Ghadbeigi, Leila, Sparks, Taylor D., Lloyd, Demetrious L., Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, Seshadri, Ram, Materials Research Laboratory, University of California, Santa Barbara, California 93106, & Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106. Enhancement of thermoelectric properties in the Nb–Co–Sn half-Heusler/Heusler system through spontaneous inclusion of a coherent second phase. United States. doi:10.1063/1.4961215.
Buffon, Malinda L. C., E-mail: mandibuffon@mrl.ucsb.edu, Verma, Nisha, Lamontagne, Leo, Pollock, Tresa M., Materials Research Laboratory, University of California, Santa Barbara, California 93106, Laurita, Geneva, Ghadbeigi, Leila, Sparks, Taylor D., Lloyd, Demetrious L., Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, Seshadri, Ram, Materials Research Laboratory, University of California, Santa Barbara, California 93106, and Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106. Sun . "Enhancement of thermoelectric properties in the Nb–Co–Sn half-Heusler/Heusler system through spontaneous inclusion of a coherent second phase". United States. doi:10.1063/1.4961215.
@article{osti_22598866,
title = {Enhancement of thermoelectric properties in the Nb–Co–Sn half-Heusler/Heusler system through spontaneous inclusion of a coherent second phase},
author = {Buffon, Malinda L. C., E-mail: mandibuffon@mrl.ucsb.edu and Verma, Nisha and Lamontagne, Leo and Pollock, Tresa M. and Materials Research Laboratory, University of California, Santa Barbara, California 93106 and Laurita, Geneva and Ghadbeigi, Leila and Sparks, Taylor D. and Lloyd, Demetrious L. and Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106 and Seshadri, Ram and Materials Research Laboratory, University of California, Santa Barbara, California 93106 and Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106},
abstractNote = {Half-Heusler XYZ compounds with an 18 valence electron count are promising thermoelectric materials, being thermally and chemically stable, deriving from relatively earth-abundant components, and possessing appropriate electrical transport properties. The typical drawback with this family of compounds is their high thermal conductivity. A strategy for reducing thermal conductivity is through the inclusion of secondary phases designed to minimize negative impact on other properties. Here, we achieve this through the addition of excess Co to half-Heusler NbCoSn, which introduces precipitates of a semi-coherent NbCo{sub 2}Sn Heusler phase. A series of NbCo{sub 1+x}Sn materials are characterized here using X-ray and neutron diffraction studies and electron microscopy. Electrical and thermal transport measurements and electronic structure calculations are used to understand property evolution. We find that annealing has an important role to play in determining antisite ordering and properties. Antisite disorder in the as-prepared samples improves thermoelectric performance through the reduction of thermal conductivity, but annealing during the measurement degrades properties to resemble those of the annealed samples. Similar to the more widely studied TiNi{sub 1+x}Sn system, Co addition to the NbCoSn phase results in improved thermoelectric performance through a decrease in thermal conductivity which results in a 20% improvement in the thermoelectric figure of merit, zT.},
doi = {10.1063/1.4961215},
journal = {Journal of Applied Physics},
number = 7,
volume = 120,
place = {United States},
year = {Sun Aug 21 00:00:00 EDT 2016},
month = {Sun Aug 21 00:00:00 EDT 2016}
}