Year: 2001
Type: article
Abstract: Thermoelectric (TE) properties (resistivity and thermopower) of polycrystalline ceramics in the Bi 2- x Pb x Sr 3- y Y y Co 2 O 9-δ system prepared by a solid-state reaction in air have been investigated as a function of temperature up to about 300 K, changing the combination of x and y . These oxides are chemically very stable, and TE properties and the lattice structures do not change even after they are heated at high temperatures. Y doping has a profound effect in reducing resistivity. When y (the amount of Y) is small, ligand holes created by O 2p-Co 3d hybridization are mainly responsible for insulating conduction. With increasing y , resistivity decreases rapidly and insulating conduction transfers to metallic conduction. This is due to the shrinkage in the lattice constant by the Y doping, which leads to band crossing of the O 2p and Co 3d levels. Measurements of TE properties including thermal conductivity have been carried out on the material with x = y = 0.5 in the high-temperature range up to 800 K. The TE figure of merit increases from 2 × 10 -5 K -1 to 7 × 10 -5 K -1 as the temperature increases from 400 K to 800 K, which indicates that this compound has high potential as a good TE material at high temperatures.
Authors: E Iguchi, T Itoga, H Nakatsugawa, F Munakata, K Furuya
Institutions: Yokohama National University, Nissan (Japan)
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W1659051597