Oxygen K-edge XANES investigation of Ni_cMg_1 − cO solid solutions

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• 作者：Dongliang Chen ; Jun Zhong ; Xiang Wu ; Ziyu Wu ; Nina Mironova-Ulmane ; Alexei Kuzmin ; Augosto Marcelli
• 关键词：XANES ; Ni_cMg_{1 −} ; cO ; Oxygen K-edge ; Hybridization
• 刊名：Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
• 出版年：2008
• 出版时间：July 2008
• 年：2008
• 卷：70
• 期：2
• 页码：458-461
• 全文大小：305 K

文摘

A series of Ni_cMg_{1 − c}O solid solutions are characterized by means of synchrotron radiation X-ray diffraction and X-ray absorption near-edge-structure spectroscopy at oxygen K-edge (532 eV). A dramatic drop of the pre-edge peak intensity is observed in the Ni_cMg_{1 − c}O system upon dilution. It can be attributed to a decrease of 3d⁸(Ni²⁺)–2p(O²⁻) mixing upon dilution with magnesium ions due to a decrease of the number of 3d vacancies as nickel ion is replaced by magnesium ion. Similarly, the decrease of the number of 4s and 4p vacancies also leads to a decrease of 4s4p(Ni²⁺)–2p(O²⁻) hybridization, and hence a drop of intensities of features B and C. The features E and F are more sensitive to the increase of the degree of disorder upon dilution than feature D, revealing that the latter is mainly dependent by the medium-range order.