以X光吸收光譜探討Ni摻雜對熱電材料CoSb3的電子結構之影響

本論文以X光吸收光譜對 (Co1-xNix)Sb3 ( x=0，0.03，0.07，0.13 ) 及不同燒結溫度之 CoSb3 ( 540、560、580°C ) 進行有系統之研究。從 Co 與 Ni 的 L3 - edge 觀察到 (Co1-xNix)Sb3 摻雜後，Co 3d 軌域可能獲得了 Ni 所提供的電子。(Co1-xNix)Sb3 在室溫時隨著摻雜濃度增加， Ni 3d 軌域提供了額外的導電電子，使的電導率上升。低摻雜濃度時，摻雜濃度增加，熱電力有序下降，Co 3d 軌域未佔據態數目的改變量跟熱電力的變化相關連。另外我們對不同燒結溫度的 CoSb3 去進行研究，從燒結溫度 540°C 升高為 560°C 時，Co 3d軌域未佔據態數目下降，電導率下降。當燒結溫度升高到 580°C 時，CoSb3 從 p - type 變成 n - type ，Co 3d 軌域未佔據態數目上升，與熱電力之結果有相關聯。

關鍵字

熱電材料； X光吸收光譜； XANES ； CoSb3 ； Skutterudite

並列摘要

We have performed x-ray absorption near edge structure (XANES) to study Ni doped thermoelectric CoSb3. Co and Ni L3 - edge XANES results indicate that there is a charge transfer from Ni 3d to Co 3d orbitals. The charge transfer, which increases with Ni concentration, may have provided more conduction electrons to the system resulting an increased electronic conductivity. Also observed is that, at low doping concentration, the number of Co 3d unoccupied states are correlated with thermopower. In addition, we have study a series of CoSb3 samples sintered at 540°C, 560°C and 580°C. Our results indicate that the Co 3d unoccupied states and the conductivity decrease with increasing sintering temperature. Sintering temperature over 560°C CoSb3 becomes n-type semiconductor, and the number of Co 3d unoccupied states are correlated with thermopower.

並列關鍵字

x-ray absorption spectroscopy ； Thermoelectric Material ； XANES ； CoSb3 ； Skutterudite

參考文獻

Abhandlungen der Deutschen Akademie Wissenschaften zu Berlin,

4003~4006, (2008)

[5] X-Ray Absorption : Principles, Application, Techniques of EXAFS, SEXAFS, SEXAFS and XANES” , edited by D. C. Koningsberger, and R.Prins, Chem. Analysis Vol. 92 (Wiley 1988).

[10] Synchrotron Radiation Research”, edited by H. Winick, S. Doniach (1980).

[14] Wei-Shu Liu et al., J. Phys. D: Appl. Phys. 40, 566~572, (2007)

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以X光吸收光譜探討Ni摻雜對熱電材料CoSb3的電子結構之影響

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