Heusler-type Fe2VSi 合金在溫度降低至臨界溫度TS ＝123K時，其晶體結構會由立方(cubic)結構轉變為正方(tetragonal)結構。在此溫度附近，許多物理性質皆有異常特徵出現。在本篇論文中，我們製作了一系列非理想配比Fe2VSi1-xAlx(x=0~0.25)樣品，期望藉由摻雜過程提升Fe2VSi合金之實用性，同時將實驗結果與其他Heusler-type合金作比較。在量測了電阻率(ρ)、熱傳導率(κ)、熱電係數(S)以及比熱(CP)之後，我們發現隨著鋁摻雜濃度提升，這些物理性質的異常特徵有減緩的趨勢，且相轉變溫度也隨著降低，在x≧0.25時相變現象消失。摻雜濃度低時，電阻率由鋁電洞摻雜濃度主宰，摻雜濃度高時，晶格無序對電阻率有決定性的影響。在所有樣品中，晶格熱傳導率( )為熱傳導率的主要貢獻，表示聲子攜帶大部分的熱流。熱電係數均為負值，顯示熱導性主要來自電子，屬於n-type材料。由相變所引起之熵(entropy)改變量( )隨x增加而減少。電阻率及比熱展現熱遲滯(thermal hysteresis)現象，顯示此類相變屬於一階相變(first-order transition)。另外，熱電效率因為鋁的摻雜而大幅提升，在x＝0.15時達到最大值。

　Heusler-type Fe2VSi compound exhibits a structural transition from cubic to tetragonal at critical temperature TS ＝123K. Near this temperature, many physical quantities exhibit anomalous features. In this thesis, we prepared a series of nonstoichiometric compounds Fe2VSi1-xAlx ( x=0~0.25 ). After measuring the electrical resistivity (ρ), thermal conductivity (κ), Seebeck coefficient (S), as well as specific heat (CP), we found that as increasing the doping concentration of Al, these anomalous features become weaker and the transition temperature decreases. When x≧0.25, the phase transition disappears. For the low-doped sample, the electrical resistivity mainly depends on the hole doping concentration of Al. With high substitution level, the crystal disorder has decidable influenced. For all samples, the thermal conductivity is mainly attributed to lattice thermal conductivity( ), indicating that the phonons carry the greater part of the heat current. Seebeck coefficient for all samples is negative, implying that the electrical conduction mainly come from the electrons and reveals the n-type characteristic. As x increase, entropy change( ) caused by phase transition decreases. Thermal hysteresis behavior exist in electrical resistivity and specific heat, suggesting that the phase transition is first-order. Besides, because Si sites are replaced by Al atoms, the thermoelectric performance improves and reachs its maximum at x＝0.15.

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