Local Structure of Amorphous EuO-TiO2 Thin Films Probed by X-Ray Absorption Fine Structure
Local Structure of Amorphous EuO-TiO2 Thin Films Probed by X-Ray Absorption Fine Structure
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X射线吸收精细结构探测非晶EuO-TiO2薄膜的局域结构
DOI：
10.1111/j.1551-2916.2011.04849.x
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
K.Tanaka
中科院分区：
文献类型：
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作者：
Y.Zong;K.Fujita;H.Akamatsu;S.Nakashima;S.Murai;K.Tanaka
我们研究了 EuO-TiO2 体系中非晶氧化物的局部结构，以了解最近在该体系中观察到的令人好奇的铁磁特性的产生机制。对脉冲激光沉积法制备的非晶 EuTiO3 和 Eu2TiO4 薄膜进行了 X 射线吸收光谱分析。 TiK边缘X射线吸收近边缘结构（XANES）和扩展X射线吸收精细结构（EXAFS）数据分析表明，非晶薄膜中Ti4+的配位数约为4，这与其晶体对应物形成鲜明对比，其中Ti4+离子与氧化物离子以八面体配位。因此推测Ti4+在非晶氧化物的随机网络结构中充当网络形成阳离子。从EuL3-edge EXAFS数据分析发现，非晶薄膜中Eu2+的配位数要低得多，并且最近的Eu-O键长比晶体薄膜中的要短。根据 Eu2+ 离子周围的局部环境，讨论了在 EuO-TiO2 体系中观察到的非晶化诱导的铁磁相互作用的增强。
We have investigated the local structure of amorphous oxides in EuO–TiO2system to understand the mechanism that gives rise to curious ferromagnetic properties recently observed in the system. X‐ray absorption spectroscopy has been performed on amorphous EuTiO3and Eu2TiO4thin films prepared by the pulsed‐laser‐deposition method. The TiK‐edge X‐ray absorption near‐edge structure (XANES) and extended X‐ray absorption fine structure (EXAFS) data analyses reveal that the coordination number of Ti4+in the amorphous thin films is around 4, which is in sharp contrast to their crystalline counterparts, where Ti4+ions are octahedrally coordinated by oxide ions. It is therefore inferred that Ti4+acts as a network‐forming cation in the random network structure of the amorphous oxides. From the EuL3‐edge EXAFS data analyses, it is found that the coordination number of Eu2+is much lower and the nearest Eu–O bond length is shorter in the amorphous thin films than in the crystalline counterparts. The amorphization‐induced enhancement of ferromagnetic interactions observed in the EuO–TiO2system is discussed in terms of the local environment around Eu2+ions.