X光吸收光譜對Heusler化合物Ni2+xMn1-xGa ( x=0 ~ 0.24 )之研究

X-ray Absorption Spectroscopy Study of Heusler compounds Ni2+xMn1-xGa (x=0.0 ~ 0.24)

陳禹男(Yu-Nan Chen)

指導教授 ： 張經霖

淡江大學/理學院/物理學系碩士班/碩士(2007年)

https://doi.org/10.6846/TKU.2007.00848

摘要

本論文的工作是利用X光吸收近邊結構光譜(X-ray Absorption Near-Edge Structure (XANES))研究Heusler化合物Ni2+xMn1-xGa( x=0 ~ 0.24 )電子結構隨著Ni/Mn含量的變化。隨著鎳的濃度增加，從鎳 K-edge和L-edge我們可以觀測到，隨著鎳含量的增加，有電子從3d軌域轉移到4p軌域的現象，而鎳的平均價數也隨之提高；從錳的K-edge可以觀察到隨著錳含量的減少，Mn2+的貢獻提高而Mn3+的貢獻減少，這顯示了錳的平均價數有減少的趨勢。此外，從鎳和錳的L3-edge半高寬可以發現，當鎳逐漸取代錳，原子結構有明顯的改變，同時鎳和錳周圍原子的穩定度也隨之提高。

關鍵字

X光吸收能譜 ； 形狀記憶合金

並列摘要

We have studied the electronic structure of martensitic compounds Ni2MnGa by x-ray absorption near edge structure (XANES). The ratio of Ni to Mn was varied in order to investigate the structural and magnetic properties in these materials. We observed systematic variations in XANES in a series of Ni2+xMn1-xGa (x=0.0 ~ 0.24) samples. In Ni K-edge and L-edge spectra, we observed electron transfer from Ni 3d to 4p orbital and the average of Ni valance increased by increasing Ni concentration. In Mn K-edge spectra, we observed the average valance of Mn decrease from 3+ with increasing Ni concentration. Atomic structure changed as Ni/Mn ratio increase, and the local structure is more stable at higher Ni concentration.

並列關鍵字

XANES ； Ni2MnGa

參考文獻

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