1. Electrical transport properties of F-doped LaFeAsO oxypnictide
- Author
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Zhao, Li-Dong, Berardan, David, and Dragoe, Nita
- Subjects
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TRANSPORT properties of metal , *ELECTRIC properties of metals , *SOLID state chemistry , *SEMICONDUCTOR doping , *DENSITY wave theory , *POLYCRYSTALS , *THERMOELECTRIC materials , *TEMPERATURE effect - Abstract
Abstract: A series of LaFeAsO1−x F x (x =0–0.225) oxyarsenides have been synthesized by a solid-state reaction method in order to optimize electrical transport properties through appropriate F doping. Both electrical resistivity and Seebeck coefficient of undoped LaFeAsO show an anomaly at about 150K, which is related to a structural phase and/or spin-density-wave (SDW) transition. Seebeck coefficient seems to be determined by two competitive factors: it is enhanced by suppressing the structural phase and/or SDW transition, and reduced by increasing carrier concentration. Seebeck coefficient is significantly enhanced just after suppressing the anomaly, and the maximum Seebeck coefficient reached −142μV/K for the sample with F doping x =0.075 from −58μV/K for undoped LaFeAsO, and then decreased with further increasing carrier concentration through F doping. Meanwhile, the electrical resistivity is decreased with increasing F doping, resulting in a maximum power factor value of 1.2mW/mK2 at 80K for polycrystalline LaFeAsO0.85F0.15 sample, this value is the same order as that of the best low temperature thermoelectric Bi88Sb12 compounds, and could be significantly higher in single crystals. [ABSTRACT FROM AUTHOR]
- Published
- 2010
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