以X光吸收光譜研究Cu-Ni合金之電子結構

The electronic structure of Cu-Ni alloys studied by X-ray absorption spectroscopy

吳佳澤(Chia-Tse Wu)

指導教授 ： 張經霖

淡江大學/理學院/物理學系碩士班/碩士(2016年)

https://doi.org/10.6846/TKU.2016.00512

摘要

我們以X光吸收光譜對不同濃度比例的Cu1-xNix合金（x=0.2，0.3，0.4，0.5）進行有系統之研究。在Cu的K-edge光譜中，Cu 4p空軌域隨著Ni濃度的增加而上升，而Cu 3d-4p空軌域會隨著Ni濃度的增加而下降。在Ni的K-edge光譜中，Ni 4p空軌域會隨著Ni濃度的增加而上升，而Ni 3d-4p空軌域隨著Ni濃度的增加而沒有明顯變化。由Cu的L3-edge面積積分顯示，隨著Ni濃度的增加，x＞0.3的樣品，Cu 3d空軌域會有序下降。由Ni的L3-edge面積積分顯示，隨著Ni濃度的增加，x＞0.3的樣品，Ni 3d空軌域會有序下降。根據實驗結果得到推測，Cu1-xNix合金隨著Ni濃度的增加，會有電子由4p軌域轉移至3d軌域的現象，進而使導電率和熱導率下降，並且由L3-edge面積積分與熱電力的比較，我們發現了Cu 3d空軌域數目的改變量會與熱電力之結果有相關聯。

關鍵字

X光吸收光譜 ； Cu-Ni合金 ； 熱電材料

並列摘要

We have performed x-ray absorption near edge structure (XANES) study on a series of thermoelectric Cu-Ni alloys samples. Cu K-edge spectra indicate that the Cu 4p unoccupied state increases as Ni concentration increases. Ni K-edge spectra indicate that the Ni 4p unoccupied state increases as Ni concentration increases. When Ni concentration x is great than 0.3, Cu 3d and Ni 3d unoccupied states as indicated by the L3-edge absorption intensity, both decrease with increasing Ni concentration. We speculate that Cu 4p-to-3d and Ni 4p-to-3d electronic transfers are responsible for the decreased electric and thermal conductivity. From Cu L3-edge spectra, the absorption intensity indicate that the variation in Cu 3d unoccupied state is related to thermopower.

並列關鍵字

X-ray absorption spectroscopy ； XANES ； Cu-Ni alloys ； Thermoelectric material

參考文獻

[1] Seebeck, T. J. "Magnetic polarization of metals and minerals." Abhandlungen der Deutschen Akademie der Wissenschaften zu Berlin 265 (1822): 1823.

[2] Sales, B. C., et al. "Filled skutterudite antimonides: Electron crystals and phonon glasses." Physical Review B 56.23 (1997): 15081.

[3] Tang, Xinfeng, et al. Applied physics letters 90.1 (2007): 12102-12102

[4] Onat, Berk. "An optimized interatomic potential for Cu- Ni alloys with the embedded-atom method." Journal of Physics: Condensed Matter 26.3 (2013): 035404.

[6] Koningsberger, D. C., and Roelof Prins. "X-ray absorption: principles, applications, techniques of EXAFS, SEXAFS, and XANES." (1988).