Department of Physics, Quaid-i-Azam University, Islamabad, Pakistan.
J Phys Condens Matter. 2013 Apr 17;25(15):156005. doi: 10.1088/0953-8984/25/15/156005. Epub 2013 Mar 25.
Li co-doped ZnO:Co (Zn0.96-yCo0.04LiyO , y ≤ 0.1) nanoparticles were synthesized by the sol-gel technique and the correlation between the structural, electronic and magnetic properties was investigated. All the samples show a single phase hexagonal (wurtzite) ZnO structure and no secondary phases were detected. Variational trends in lattice parameters suggest the incorporation of Li in the ZnO:Co system in both substitutional and interstitial sites. Detailed electronic studies have been performed by high-resolution x-ray photoelectron spectroscopy (XPS) to determine the states of Zn, O, Co and Li. It was determined that Co substitutes at Zn sites (CoZn) while the O vacancy and Zn defects did not show much variation with increasing Li concentration. Deconvolution of the Li XPS peak showed a clear non-monotonic trend in the variation of the substitutional Li (LiZn) and interstitial Li (Lii) defects with increasing Li concentration in the particles. The magnetization study of the samples showed that the variation of the moment closely followed the trend of variation of the LiZn defects. The data are interpreted in terms of substitutional Li acting as a hole dopant and optimizing the conditions for ferromagnetism in Co-doped ZnO. Interstitial Li is not seen to be playing this role.
Li 共掺杂 ZnO:Co（Zn0.96-yCo0.04LiyO，y≤0.1）纳米粒子通过溶胶-凝胶法合成，并研究了其结构、电子和磁性能之间的相关性。所有样品均显示出单相六方（纤锌矿）ZnO 结构，未检测到第二相。晶格参数的变化趋势表明 Li 以替位和填隙两种方式掺入 ZnO:Co 体系。通过高分辨率 X 射线光电子能谱（XPS）进行了详细的电子研究，以确定 Zn、O、Co 和 Li 的状态。确定 Co 取代 Zn 位（CoZn），而随着 Li 浓度的增加，O 空位和 Zn 缺陷的变化不大。Li XPS 峰的分峰表明，随着颗粒中 Li 浓度的增加，取代 Li（LiZn）和填隙 Li（Lii）缺陷的变化呈现出明显的非单调趋势。样品的磁化研究表明，磁矩的变化很好地遵循了 LiZn 缺陷变化的趋势。数据根据替代 Li 作为空穴掺杂剂来解释，并优化 Co 掺杂 ZnO 中产生铁磁的条件。未观察到填隙 Li 起作用。
