Enhanced thermoelectric properties of Mg2Si by addition of TiO2nanoparticles

Autor:	Nader Farahi, Daniel Cederkrantz, Anders Palmqvist, Mats Nygren, Bo B. Iversen, Kasper A. Borup
Rok vydání:	2012
Předmět:	Electron mobility Thermal conductivity Materials science Electrical resistivity and conductivity Seebeck coefficient Metallurgy Thermoelectric effect Analytical chemistry General Physics and Astronomy Sintering Grain boundary Thermal conduction
Zdroj:	Cederkrantz, D, Farahi, N, Borup, K A, Iversen, B B, Nygren, M & Palmqvist, A E C 2011, ' Enhanced thermoelectric properties of Mg2Si by addition of TiO2 nanoparticles ', Journal of Applied Physics, vol. 111, no. 2, pp. 023701 . https://doi.org/10.1063/1.3675512
ISSN:	1089-7550 0021-8979
DOI:	10.1063/1.3675512
Popis:	The effects on the thermoelectric properties of Mg2Si when adding TiO2 nanoparticles have been evaluated experimentally. A batch of Mg2Si was prepared through direct solid state reaction and divided into portions which were mechanically mixed with different amounts of TiO2 nanoparticles ranging from 0.5 to 3 vol% and subsequently sintered to disks. All materials showed n-type conduction and the absolute value of the Seebeck coefficient was reduced with increasing amount of TiO2 added, while the electrical resistivity was greatly reduced. The thermal conductivity was surprisingly little affected by the addition of the nanoparticles. An optimum value of the thermoelectric figure-of-merit ZT = TS2 sigma/k was found for the addition of 1 vol% TiO2, showing almost three times higher ZT value than that of the pure Mg2Si. Larger TiO2 additions resulted in lower ZT values and with 3 vol% added TiO2 the ZT was comparable to the pure Mg2Si. The sintering process resulted in reduction or chemical reaction of all TiO2 to TiSi2 and possibly elemental titanium as well as reduced TiOx. The increased electrical conductivity and the decreased Seebeck coefficient were found due to an increased charge carrier concentration, likely caused by the included compounds or titanium-doping of the Mg2Si matrix. The low observed effect on the thermal conductivity of the composites may be explained by the relatively higher thermal conductivity of the included compounds, counter-balancing the expected increased grain boundary scattering. Alternatively, the introduction of compounds does not significantly increase the concentration of scattering grain boundaries.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_dedup___::2a896b9a3a60eeebe4d2c7cfafa16ed5 https://doi.org/10.1063/1.3675512 Zobrazit plný text záznamu