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Local Structural Studies Through EXAFS and Effect of Fe2+or Fe3+ Existence in ZnO Nanoparticles
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2021-06-15 , DOI: 10.1021/acs.jpcc.1c00881
Chithira Pulickalputhenpura Rajan 1 , Nagendra Abharana 2 , Shambhu Nath Jha 3 , Dibyendu Bhattacharyya 2 , Teny Theresa John 1
Affiliation  

A simple solution-based chemical precipitation method was used to synthesize the Fe-doped ZnO nanoparticles. X-ray Photoelectron Spectroscopy (XPS) measurement showed that mostly Fe2+ ions are incorporated in a lower percentage of Fe doping, while a higher percentage leads to Fe3+. The broad absorption band in the visible range shows the d–d crystal field transitions between the multiplets of 3d5 configuration of the high spin Fe3+ substituting Zn2+ under the influence of a tetrahedral ZnO crystal field. Raman measurement also supports the optical absorption data. ESR results show that the occurrence of broad signals is due to the exchange interactions among the TM ions in the doped samples. Fe exists in a mixed phase in Fe1 and the wide curve in Fe10 is due to the exchange interaction among Fe3+– Fe3+. EXAFS measurements confirm that the spectral features showing the peak edge position is similar to Fe2O3 corresponding to the Fe3+ state. From this, it can be inferred that Fe exists mostly in a +3 oxidation state in all the samples, but there may be existence of +2 states in the surface layers as observed from XPS measurement. Fe1 shows RTFM with a coercivity of ∼70 Oe. The non-saturating, linear magnetic moment at higher applied magnetic field is due to the paramagnetic contribution from the uncoupled Fe3+ ions.

中文翻译:

通过 EXAFS 的局部结构研究和 Fe 2+或 Fe 3+存在于 ZnO 纳米颗粒中的影响

一种简单的基于溶液的化学沉淀方法用于合成 Fe 掺杂的 ZnO 纳米粒子。X 射线光电子能谱 (XPS) 测量表明,大部分 Fe 2+离子以较低百分比的 Fe 掺杂,而较高百分比导致 Fe 3+。可见光范围内的宽吸收带显示了高自旋 Fe 3+取代 Zn 2+的 3d 5构型的多重峰之间的 d-d 晶体场跃迁在四面体 ZnO 晶体场的影响下。拉曼测量还支持光吸收数据。ESR 结果表明,宽信号的出现是由于掺杂样品中 TM 离子之间的交换相互作用。Fe以混合相形式存在于Fe1中,Fe10中的宽曲线是由于Fe 3+ - Fe 3+之间的交换相互作用。EXAFS 测量证实,显示峰边缘位置的光谱特征类似于 Fe 2 O 3对应的 Fe 3+状态。由此可以推断,在所有样品中,Fe 主要以 +3 氧化态存在,但从 XPS 测量观察到,表层中可能存在 +2 态。Fe1 显示出矫顽力约为 70 Oe 的 RTFM。在较高外加磁场下的非饱和线性磁矩是由于未耦合的 Fe 3+离子的顺磁性贡献。
更新日期:2021-06-24
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