- 學位論文
以X光吸收光譜研究鋁摻雜之Heusler化合物Fe2VSi
X-ray absorption spectroscopy study of Al doped Heusler compounds Fe2VSi
摘要
本論文以X光近邊緣結構吸收光譜 (X-ray Absorption Near Edge Structure，XANES)研究Heusler 化合物Fe2VSi1-xAlx(x=0.00~0.25)之電子結構。我們可以發現Al摻雜對Al 3p-Fe 3d以及Al 3p-V 3d是有相當強的混成。而在Fe的L3-edge的空軌域數目隨著Al摻雜的增加而增加(Fe的電洞數目增加)，在摻雜量x=0.15時電洞的數目達到最大值，之後持續增加Al摻雜量，Fe的L3-edge空軌域的數目卻有下降的趨勢(電洞數目減少)，而Fe的L3-edge的空軌域數目與電阻率以及熱電勢呈一相反的走勢，因此我們發現了Fe電洞濃度與熱電性質的關連性。而我們由Fe K-edge的吸收光譜中可以發現，隨著Al的摻雜並不會使其吸收峰有明顯的改變。
並列摘要
We have performed x-ray absorption near edge structure (XANES) study on a series of Fe2VSi based Heusler type compounds to study the correlations between electronic structure and the thermoelectric property. A series of Fe2VSi1-xAlx compounds with different Al concentrations (x form 0 to 0.25) were studied. The XANES results show that the unoccupied density of states above Fermi level increases with increasing Al concentration, which is positively correlated with the measured resistivity and the Seebeck coefficient data. On the other hand, increased Al concentration does not affect the hybridization between transition metal V and Fe.