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455 results on '"Tritt, Terry M."'

1. High Thermoelectric Figure of Merit by Resonant Dopant in Half-Heusler Alloys

Author

Chen, Long, Liu, Yamei, He, Jian, Tritt, Terry M., and Poon, S. Joseph

Subjects
Condensed Matter - Materials Science
Abstract

Half-Heusler alloys have been one of the benchmark high temperature thermoelectric materials owing to their thermal stability and promising figure of merit ZT. Simonson et al. early showed that small amounts of vanadium doped in Hf0.75Zr0.25NiSn enhanced the Seebeck coefficient and correlated the change with the increased density of states near the Fermi level. We herein report a systematic study on the role of vanadium (V), niobium (Nb), and tantalum (Ta) as prospective resonant dopants in enhancing the ZT of n-type half-Heusler alloys based on Hf0.6Zr0.4NiSn0.995Sb0.005. The V doping was found to increase the Seebeck coefficient in the temperature range 300-1000 K, consistent with a resonant doping scheme. In contrast, Nb and Ta act as normal n-type dopants, as evident by the systematic decrease in electrical resistivity and Seebeck coefficient. The combination of enhanced Seebeck coefficient due to the presence of V resonant states and the reduced thermal conductivity has led to a state-of-the-art ZT of 1.3 near 850 K in n-type (Hf0.6Zr0.4)0.99V0.01NiSn0.995Sb0.005 alloys., Comment: Submitted to AIP Advances

Published
2017

2. Recent Advances in Nanostructured Thermoelectric Half-Heusler Compounds

Author

Xie, Wenjie, Weidenkaff, Anke, Tang, Xinfeng, Zhang, Qingjie, Poon, Joseph, and Tritt, Terry M.

Subjects
Condensed Matter - Materials Science
Abstract

Half-Heusler (HH) alloys have attracted considerable interest as promising thermoelectric (TE) materials in the temperature range around 700 K and above, which is close to the temperature range of most industrial waste heat sources. The past few years have seen nanostructuing play an important role in significantly enhancing the TE performance of several HH alloys. In this article, we briefly review the recent progress and advances in these HH nanocomposites. We begin by presenting the structure of HH alloys and the different strategies that have been utilized for improving the TE properties of HH alloys. Next, we review the details of HH nanocomposites as obtained by different techniques. Finally, the review closes by highlighting several promising strategies for further research directions in these very promising TE materials., Comment: 34 pages, 22 figures

Published
2013
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3. Significant ZT Enhancement in p-type Ti(Co,Fe)Sb-InSb Nanocomposites via a Synergistic High Mobility Electron Injection Energy filtering and Boundary Scattering Approach

Author

Xie, Wenjie, Yana, Yonggao, Zhuc, Song, Zhouc, Menghan, Populohb, Sascha, Gałązkab, Krzysztof, Poon, S. Joseph, Weidenkaff, Anke, He, Jian, Tanga, Xinfeng, and Tritt, Terry M.

Subjects
Condensed Matter - Materials Science
Abstract

It has been demonstrated that InSb nanoinclusions, which are formed in situ, can simultaneously improve all three individual thermoelectric properties of the n-type half Heusler compound (Ti,Zr,Hf)(Co,Ni)Sb [Xie et al., Acta Mater. 58, 4795 (2010)]. In the work presented herein, we have adopted the same approach to the p-type half Heusler compound Ti(Co,Fe)Sb. The results of resistivity, Seebeck coefficient, thermal conductivity, and Hall coefficient measurements indicate that the combined high mobility electron injection, low energy electron filtering, and boundary scattering, again, lead to a simultaneous improvement of all three individual thermoelectric properties: enhanced Seebeck coefficient and electrical conductivity as well as reduced lattice thermal conductivity. A figure of merit of ZT=0.33 was attained at 900 K for the sample containing 1 atomic percent InSb nanoinclusions, a 450 percent improvement over the nanoinclusion-free sample. This represents a rare case that the same nanostructuring approach successfully works for both p-type and n-type thermoelectric materials of the same class, hence pointing to a promising materials design route for higher performance half-Heusler materials in the future and hopefully will realize similar improvement in TE devices based on such half Heusler alloys., Comment: 227 pages, 9 figures

Published
2013

38. Overview of thermoelectric sodium cobaltite: [Na.sub.x][Co.sub.2][O.sub.4]

Author

Tang, Xiaofeng and Tritt, Terry M.

Subjects
Health, Science and technology, Social sciences
Abstract

An overview of the crystal structure, synthesis techniques for single crystal and polycrystalline [Na.sub.x][Co.sub.2][O.sub.4] and their thermoelectric properties are presented. The study on the strong electron correlation in this oxide which is believed to be the likely source of the enhanced thermopower is reviewed. The recently discovered superconducting behavior for the Na-deficient hydrated compound [Na.sub.x][Co.sub.2][O.sub.4] x y[H.sub.2]O is also discussed., 1. Introduction Thermoelectric (TE) technology for energy conversion between heat and electricity via Seebeck and Peltier effects provides a viable method for solid state cooling and remote power supply. In [...]

Published
2008

39. Solution chemical synthesis of nanostructured thermoelectric materials

Author

Ji, Xiaohua, Tritt, Terry M., Zhao, Xinbing, and Kolis, Joe. W.

Subjects
Health, Science and technology, Social sciences
Abstract

The ability to mass produce thermoelectric nano-powders is crucial to the thermoelectric nano and nano-composite research. Solution chemical synthesis, such as hydrothermal, solvothermal and low temperature solution chemical syntheses are effectual approaches to manufacture nano materials with acceptable yield. By carefully designing the reaction agents and controlling the synthesis parameters, numerous nanoscale materials with various morphologies could be achieved. In this paper, the synthesis of nanosized state-of-the-art thermoelectric materials, such as [Bi.sub.2][Te.sub.3], Co[Sb.sub.3], PbTe & PbSe, [Bi.sub.2][S.sub.3] etc. were presented, their multiple morphologies were displayed, and the underlying reaction mechanisms were discussed. Our lately developed hydrothermal nano-plating technique was also briefly introduced., 1. Introduction The performance of a thermoelectric (TE) material is evaluated by its figure of merit Z = [α.sup.2]/ρκ, where α is the Seebeck coefficient, ρ is the electrical resistivity, [...]

Published
2008

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