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Thermal stability and thermoelectric properties of p-type Ba8Ga16Ge30 clathrates

Daniel Cederkrantz (Institutionen för kemi- och bioteknik, Teknisk ytkemi) ; A. Saramat ; G. J. Snyder ; Anders Palmqvist (Institutionen för kemi- och bioteknik, Teknisk ytkemi)
Journal of Applied Physics (0021-8979). Vol. 106 (2009), 7, p. 074509 (artno).
[Artikel, refereegranskad vetenskaplig]

The thermal stability of p-type Ba(8)Ga(16)Ge(3)0 clathrates grown from gallium flux has been tested by heat treatment in low pressure Ar atmosphere at 400, 600, and 800 degrees C. Significant gallium loss was observed for all samples during heat treatment. The treatment at 400 degrees C does not significantly change the sample properties, and the samples remain p-type and comparable to the untreated, as-prepared, sample. At 600 degrees C the sample switches from extrinsic p-type to extrinsic n-type, presumably due to significant loss of Ga, and shows a high thermopower but a reduced electrical conductivity compared to as-made n-type samples. Surprisingly, after a thermal treatment at 800 degrees C, the crystal structure seemingly loses less Ga, only reducing the hole concentration to near intrinsic levels and thus has a negative impact on ZT. Regardless of the heat treatment temperature of the p-type samples the thermal conductivity remained exceptionally low, for some samples 0.9 W/m K. Heat treatment can thus greatly affect the thermoelectric properties of p-type Ba(8)Ga(16)Ge(3)0, but the crystal structure remains intact. (C) 2009 American Institute of Physics. [doi: 10.1063/1.3236635]

Nyckelord: purity

Denna post skapades 2010-02-24.
CPL Pubid: 114540


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Institutioner (Chalmers)

Institutionen för kemi- och bioteknik, Teknisk ytkemi (2005-2014)


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Chalmers infrastruktur

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Thermoelectric Ba8Ga16Ge30 clathrates for waste heat recovery