Different effects of grain boundary scattering on charge and heat transport in polycrystalline platinum and gold nanofilms
Ma Wei-Gang(马维刚)a), Wang Hai-Dong(王海东)a), Zhang Xing(张兴)a)†, and Takahashi Kojib)
aKey Laboratory for Thermal Science and Power Engineering of Ministry of Education,Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China; bGraduate School of Engineering, Kyushu University, Fukuoka 819-0395, Japan
Abstract The in-plane electrical and thermal conductivities of several polycrystalline platinum and gold nanofilms with different thicknesses are measured in a temperature range between the boiling point of liquid nitrogen (77K) and room temperature by using the direct current heating method. The result shows that both the electrical and thermal conductivities of the nanofilms reduce greatly compared with their corresponding bulk values. However, the electrical conductivity drop is considerably greater than the thermal conductivity drop, which indicates that the influence of the internal grain boundary on heat transport is different from that of charge transport, hence leading to the violation of the Wiedemann--Franz law. We build an electron relaxation model based on Matthiessen's rule to analyse the thermal conductivity and employ the Mayadas & Shatzkes theory to analyse the electrical conductivity. Moreover, a modified Wiedemann--Franz law is provided in this paper, the obtained results from which are in good agreement with the experimental data.
Received: 07 October 2008
Revised: 10 November 2008
Accepted manuscript online:
Fund: Project supported by the National
Natural Science Foundation of China (Grant Nos 50676046 and
50730006).
Cite this article:
Ma Wei-Gang(马维刚), Wang Hai-Dong(王海东), Zhang Xing(张兴), and Takahashi Koji Different effects of grain boundary scattering on charge and heat transport in polycrystalline platinum and gold nanofilms 2009 Chin. Phys. B 18 2035
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