Thermo-Electric Properties of Cu and Ni Nanoparticles Packed Beds
The hot-wire method and the four-probe resistivity method are applied to probe the thermal conductivity (k) and the electric conductivity (σ) of Cu and Ni nanoparticle packed beds (NPBs). A fitting method based on classical physical theory is devised to separate
ke
(electronic thermal conductivity) and kp
(phonon thermal conductivity) from k at room temperature. Results turn out that kp
only accounts for a small proportion of k (4–20%); the proportion decreases with increasing
porosity or temperature. Most importantly, this fitting method provides a simple way to separate ke
and kp
from k at room temperature. The Wiedemann-Franz law is checked and is found to be unsuitable for NPBs. The Lorenz number (L) is calculated
from measurements of ke
, k, and σ. Results turn out that L is found to be 50–60 times that of the bulk. With a Seebeck coefficient (S) measured, the thermoelectric property of NPBs is also calculated. We find that the NPB possess an
advantage in thermoelectric property than bulk, the thermoelectric figure of merit (ZT) of Ni (Cu) NPBs can be 20.17 (1.87) times that of bulk Ni (Cu). The effect of porosity on ZT is also discussed, and results show that a NPB with a small porosity is more preferable as a thermoelectric material.
With a small porosity, ZT can be even 1.73 times that of a large porosity. Although metals are not good thermoelectric material, the method in this paper supplies a way to improve the thermoelectric property of other thermoelectric materials.
Keywords: Lorenz Number; Nanoparticle Packed Bed; Nanoporous Material; Thermal Conductivity; Thermoelectric Material
Document Type: Research Article
Affiliations: School of Electrical and Power Engineering, China University of Mining and Technology, Xuzhou 221116, China
Publication date: 01 May 2018
- Journal for Nanoscience and Nanotechnology (JNN) is an international and multidisciplinary peer-reviewed journal with a wide-ranging coverage, consolidating research activities in all areas of nanoscience and nanotechnology into a single and unique reference source. JNN is the first cross-disciplinary journal to publish original full research articles, rapid communications of important new scientific and technological findings, timely state-of-the-art reviews with author's photo and short biography, and current research news encompassing the fundamental and applied research in all disciplines of science, engineering and medicine.
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