Low-temperature electrical transport in Heusler-type Fe2V (AlSi) alloys
Low-temperature electrical transport in Heusler-type Fe2V (AlSi) alloys
复制标题
Heusler 型 Fe2V (AlSi) 合金的低温电传输
DOI：
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
V. Rao
中科院分区：
文献类型：
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作者：
M. Vasundhara;V. Srinivas;V. Rao
研究了Heusler型Fe 2 VAl 1 −xSix（0≤x≤1）合金的电阻率ρ和塞贝克系数S随温度的变化。我们已经表明，输运参数是非常敏感的掺杂。对于x = 0的样品，已经观察到高的ρ值和负的电阻率温度系数（TCR）。随着Si浓度的增加，ρ减小，TCR改变其符号，而当Al被Si取代时，S在幅度和符号上都显示出显著的变化。这些变化似乎让人联想到金属到半导体的转变。结果表明，传统的输运理论提出的金属间化合物合金或半导体不能解释在本研究的整个温度范围内的输运行为。x = 0-0.02样品的低温电阻率数据可用无带隙半导体模型描述。S和ρ的强烈组分依赖性归因于费米能处电子态密度的急剧变化。它还表明，通过最佳掺杂可以实现非常大的值的功率因数（P）。在室温下，x = 0.06时的功率因数最高（2.23 × 10−3 W mK−2），与传统热电材料的功率因数相当。在较低的温度下，发现P甚至高于常规热电材料。
The temperature variation of the electrical resistivity ρ and the Seebeck coefficient S of Heusler-type Fe2VAl1−xSix (0≤x≤1) alloys has been investigated. We have shown that the transport parameters are very sensitive to doping. For the x = 0 sample, high values of ρ and negative temperature coefficient of resistivity (TCR) have been observed. As the Si concentration increases, ρ decreases and the TCR changes its sign, while S shows significant changes in magnitude as well as sign when Al is replaced with Si. These changes appear to be reminiscent of a metal to semiconductor transition. It has been shown that the conventional transport theories proposed for intermetallic alloys or semiconductors cannot explain the transport behaviour in the whole temperature range of the present study. Low-temperature resistivity data of x = 0–0.02 samples could be described with a gapless semiconductor model. The strong composition dependence of S and ρ is attributed to the sharp variations in electronic density of states at the Fermi energy. It is also shown that by optimum doping one can achieve very large values of power factor (P). The estimated power factor at room temperature is observed to be highest (2.23 × 10−3 W mK−2) for x = 0.06 and comparable to that of conventional thermoelectric material. At lower temperatures P is found to be even higher than that of conventional thermoelectric material.