X-RAY ABSORPTION STUDIES OF CEO2, PRO2, AND TBO2 .2. RARE-EARTH VALENCE STATE BY LIII ABSORPTION EDGES
X-RAY ABSORPTION STUDIES OF CEO2, PRO2, AND TBO2 .2. RARE-EARTH VALENCE STATE BY LIII ABSORPTION EDGES
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DOI：
10.1103/physrevb.36.1750
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发表时间：
1987-07-15
影响因子：
3.7
通讯作者：
ALBERT, L
中科院分区：
文献类型：
--
作者：
DEXPERT, H;KARNATAK, RC;ALBERT, L
萤石结构相关的CeO 2，PrO 2和TbO 2的L III吸收边显示出四个分辨良好的光谱特征。它们的位置和相对强度的系统趋势表明，在这些氧化物中存在特定价态的稀土原子。本研究揭示了一个明显的4f-2 p氧重叠的价带后，最外层的4f电子完全离域的两个主要结构，最高能量的一个被解释为由于本地化的4f状态和一个额外的存在下，我们表示为4f，证明了较低的能量峰的4f外部状态。较弱的肩和preabsorptionlike功能归因于shakedown效应由于额外的屏蔽电子的存在下，这种效果发生在本地和扩展轨道的f对称性，和一个较弱的结构，因此连接到每个强峰。局域态和扩展态的共存解释内的双谷势模型。
The L III absorption edges of fluorite-structure-related CeO 2, PrO 2, and TbO 2 show four well-resolved spectral features. The systematic trend in their positions and relative intensities suggests the presence of a specific valence state of the rare-earth atom in these oxides. The present study reveals an appreciable 4f-2p oxygen overlap in the valence band following the complete delocalization of the outermost 4f electron. Of the two main structures, the highest-energy one is interpreted as due to the localized 4f state and the additional presence of a hybridized 4f external state which we denote as 4f, is evidenced by the lower-energy peak. The weaker shoulder and preabsorptionlike feature are attributed to a shakedown effect due to the presence of an additional screening electron. This effect occurs both for the localized and for the extended orbitals of f symmetry, and a weaker structure therefore attaches to each of the strong peaks. The coexistence of localized and extended states is interpreted within a double-valley-potential model.