The effects of high-pressure compression on transport and thermoelectric properties of TiS2 at low temperatures from 5 to 310K
Qin, X. Y.
Li, H. J.
Hng, Huey Hoon
Date of Issue2008
School of Materials Science and Engineering
The effects of high-pressure compression on the transport and thermoelectric properties of TiS2 were investigated at temperatures ranging from 5 to 310 K. The results indicated that compression under the pressure of 6 GPa caused a significant decrease (16-fold at 300 K) in the absolute thermopower |S| and the thermal conductivity (5-fold at 300 K). At the same time, the electrical resistivity ρ increased by two orders of magnitude after the compression. A transition from metallic state (dρ /dT>0) to semiconductorlike state (dρ /dT<0) was found to occur after the compression. This transition to the semiconductorlike state could be caused by the substantially enhanced grain boundary (GB) scattering due to the refinement of its grains to the nanoscale range, which should also be responsible for the remarkable increase in the resistivity and large decrease in thermal conductivity. Moreover, Mott’s two-dimensional variable range hopping law, ln ρ∝T-1/3, was observed at T<~100 K for TiS2 after the compression, suggesting that substantial potential disorder was produced by the high-pressure compression. The significant decrease of |S| could originate from the possible compositional disorder in the GBs of TiS2 after compression. The thermoelectric figure of merit of TiS2 decreased after the compaction due to the large decrease in |S| and increase in ρ, indicating that high-pressure compression is not beneficial to the thermoelectric performance of TiS2.
Journal of applied physics
© 2008 American Institute of Physics. This paper was published in Journal of Applied Physics and is made available as an electronic reprint (preprint) with permission of American Institute of Physics. The paper can be found at the following official URL: [http://dx.doi.org/10.1063/1.2938748]. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law.