Formation of Magneli Phase and Its Influence on Thermoelectric Properties in Preparation of TiO2-TiB2 Thermoelectric Compacts Fabricated by Spark Plasma Sintering
Year: 2019
Type: article
Abstract: Powders of TiO2 mixed with TiB2 of mmol% (m = 0, 1, 2, 3, 4, 5, 10, 12, 20) were prepared, and sintered by using an spark plasma sintering apparatus, the chemical reaction between TiO2 and TiB2 in the sintering process was investigated. In the case of m = 2 to 20, it was found TiO2 was reduced by TiB2, to form and the Magneli phases (TinO2n−1 (n = 3, 4, 5, 6)). The maximum value of the dimensionless figure of merit ZT was 0.18 at 800°C for m = 3, and almost the same value as that of the TiO2-TiN sintered bodies was obtained. The effective carrier concentrations in the TiO2-TiB2 sintered bodies were estimated from Heikes’s formula was about 2.4 times larger than those of the TiO2-TiN, TiO2-TiC, TiO2-VC sintered bodies. The electron mobility μ tends to increase as m increases. The thermal conductivity was dominated by the lattice thermal conductivity at m = 0, while the electronic thermal conductivity was suggested at m = 4 and 5. It was confirmed that the formation of the magneli phase contributes to the improvement of ZT.
DOI: 10.2497/jjspm.66.323
Authors: Yasushi SUGAWARA, Shigeaki SUGIYAMA, Kiyoshi FUDA
Institutions: Akita Industrial Technology Center, Akita University
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W2957464774