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Transport and thermoelectric propert...

Xia, Yu.

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Transport and thermoelectric properties in semiconducting and semimetallic half-Heusler compounds.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Transport and thermoelectric properties in semiconducting and semimetallic half-Heusler compounds./
Author:	Xia, Yu.
Description:	104 p.
Notes:	Source: Dissertation Abstracts International, Volume: 64-03, Section: B, page: 1305.
Contained By:	Dissertation Abstracts International64-03B.
Subject:	Physics, Condensed Matter. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoeng/servlet/advanced?query=3083075

Transport and thermoelectric properties in semiconducting and semimetallic half-Heusler compounds.
Xia, Yu.

Transport and thermoelectric properties in semiconducting and semimetallic half-Heusler compounds. - 104 p.

Source: Dissertation Abstracts International, Volume: 64-03, Section: B, page: 1305.

Thesis (Ph.D.)--University of Virginia, 2003.

A study of the thermoelectric properties in several half-Heusler alloy systems is presented. Half Heusler alloys are intermetallic compounds that crystallize in the MgAgAs-type structure. Several of the half-Heusler compounds HfNiSn, TiNiSn, and ZrNiSn were found to exhibit semiconducting behavior with Seebeck coefficients as large as −200 to −400 μV/K at room temperature. In view of their large thermopower and only moderately high resistivity, their potential as TE materials was readily pointed out.Subjects--Topical Terms:

1018743
Physics, Condensed Matter.

Transport and thermoelectric properties in semiconducting and semimetallic half-Heusler compounds.
LDR:03103nmm 2200289 4500 001 1856874
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008 130614s2003 eng d
035 $a (UnM)AAI3083075
035 $a AAI3083075
040 $a UnM $c UnM
100 1 $a Xia, Yu. $3 1931924
245 1 0 $a Transport and thermoelectric properties in semiconducting and semimetallic half-Heusler compounds.
300 $a 104 p.
500 $a Source: Dissertation Abstracts International, Volume: 64-03, Section: B, page: 1305.
500 $a Adviser: Joseph Poon.
502 $a Thesis (Ph.D.)--University of Virginia, 2003.
520 $a A study of the thermoelectric properties in several half-Heusler alloy systems is presented. Half Heusler alloys are intermetallic compounds that crystallize in the MgAgAs-type structure. Several of the half-Heusler compounds HfNiSn, TiNiSn, and ZrNiSn were found to exhibit semiconducting behavior with Seebeck coefficients as large as −200 to −400 μV/K at room temperature. In view of their large thermopower and only moderately high resistivity, their potential as TE materials was readily pointed out.
520 $a We tried to maximize the power factor of TiNiSn alloys from small amount doping. This method lowers the Seebeck coefficient a little bit and lowers the electrical conductivity dramatically, where the thermal conductivity stays about the same. The Sb doping leads to a relatively large power factor of (0.2–1.0) W/m K at room temperature for small concentrations of Sb. These values are comparable to that of Bi<sub>2</sub>Te<sub>3</sub> alloys, which are the current state-of-the-art thermoelectric materials. The power factor is much larger at <italic>T</italic> &sim; 650K where it is &sim;4.5 W/m K making these materials very attractive for potential power generation considerations.
520 $a We tried to decrease the thermal conductivity from multi-component substitution. This method will increase the phonon scattering and lower the thermal conductivity. (ZrHf)(CoPt)(SbSn) is the system we chose. The large mass difference between Zr, Hf and between Co, Pt helps increase the phonon scattering. It is also easy to keep VEC to be 18 and achieve the electron or hole doping effect by varying the content of different components slightly. The lowest thermal conductivity obtained in the substituted alloys is &sim;3.0 W/m K at 300K, which is among the lowest reported for this class of structural phases.
520 $a We used ball milling to decrease the grain size of the half-Heusler alloys. The boundary scattering decreases the thermal conductivity. The lattice thermal conductivity decreases from &sim;10 W/m K to 3.7 W/m K in ball milled and shock compacted alloys. This method opens possibilities for optimizing figure of merit by adjusting the grain sizes in these half-Heusler alloys.
590 $a School code: 0246.
650 4 $a Physics, Condensed Matter. $3 1018743
690 $a 0611
710 2 0 $a University of Virginia. $3 645578
773 0 $t Dissertation Abstracts International $g 64-03B.
790 1 0 $a Poon, Joseph, $e advisor
790 $a 0246
791 $a Ph.D.
792 $a 2003
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoeng/servlet/advanced?query=3083075