E138-04 - Forschungsbereich Quantum Materials E138-03 - Forschungsbereich Functional and Magnetic Materials
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Journal:
Journal of Materials Research
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ISSN:
0884-2914
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Date (published):
2011
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Number of Pages:
5
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Publisher:
CAMBRIDGE UNIV PRESS
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Peer reviewed:
Yes
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Keywords:
Mechanical Engineering; Mechanics of Materials; Condensed Matter Physics; General Materials Science; thermoelectric; clathrates; rapid solidification
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Abstract:
Ba8Ga16−xGe30+x is the clathrate with the highest thermoelectric figure of merit known to date. However, no p-type material could be obtained by conventional synthesis from the melt. Here we show that the time and cost-effective melt spinning technique can produce Ba8Ga16−xGe30+x in a metastable state, where x can be varied continuously from negative to positive values, resulting in both p- and n-type materials. The quenched phases were characterized by x-ray powder diffraction and transmission electron microscopy. It was surprising that they were perfectly crystalline, with large grain sizes of the order of a micrometer. Temperature dependent measurements of the electrical resistivity, Hall effect, thermopower, and thermal conductivity are presented and discussed in terms of a two-band model.
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Research Areas:
Sustainable Production and Technologies: 40% Special and Engineering Materials: 60%