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首页> 外文期刊>The journal of physical chemistry, C. Nanomaterials and interfaces >Structure, Optical, and Room-Temperature Ferromagnetic Properties of Pure and Transition-Metal-(Cr, Mn, and Ni)-Doped ZnO Nanocrystalline Films Grown by the Sol-Gel Method
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Structure, Optical, and Room-Temperature Ferromagnetic Properties of Pure and Transition-Metal-(Cr, Mn, and Ni)-Doped ZnO Nanocrystalline Films Grown by the Sol-Gel Method

机译：Sol-Gel法生长的纯金属和过渡金属掺杂的（Cr，Mn和Ni）掺杂的ZnO纳米晶膜的结构，光学和室温铁磁性能

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摘要

Transition-metal-(Cr, Mn, and Ni)-doped zinc oxide (ZnO) with the concentration of 2.5% and pure ZnO nanocrystalline (nc) films have been fabricated on quartz substrates by the sol-gel method. The X-ray diffraction analysis shows that the films are polycrystalline with the wurtzite phase. The E2~(high) phonon mode shifts about 7 cm~(-1) with different transition metals, and the A1(LO) phonon mode redshifts 4 cm~(-1) with the ionic radius of doping elements. From the transmittance spectra, all films are highly transparent in the visible region and exhibit Urbach tail states in the ultraviolet range because of the, crystalline, defects and grain boundaries. The optical band gap of the films decreases with increasing the orbital occupation numbers of 3d electrons due to the orbital splitting of magnetic ions. It was found that a distinct and strong excitonic transition appears beyond the fundamental absorption region at room temperature. Ultraviolet and near-infrared electronic transitions can be observed and show the strong relationship with the transition metal doping. Moreover, orange, yellow and red luminescences strongly depend on the doping elements owing to different oxygen vacancy, oxygen interstitial, and surface morphology. Magnetic measurement results reveal that all the transition-metal-doped nc-ZnO films show the well-defined ferromagnetic features at room temperature. In particular, the nc-ZnO film doped with Mn shows the largest saturation magnetic moment, which agrees well with the theoretical predication. The ferromagnetic properties could be derived from the doping of magnetic ions, intrinsic defects, interfaces, and grain boundaries in the transition-metal-doped nc-ZnO materials.
机译：采用溶胶-凝胶法在石英衬底上制备了浓度为2.5％的过渡金属掺杂（Cr，Mn和Ni）的氧化锌（ZnO）和纯ZnO纳米晶（nc）薄膜。 X射线衍射分析表明该膜是具有纤锌矿相的多晶。在不同过渡金属的作用下，E2〜（高）声子模位移约7 cm〜（-1），Al（LO）声子模随掺杂元素的离子半径红移4 cm〜（-1）。从透射光谱来看，所有的膜在可见光区域都是高度透明的，并且由于晶体，缺陷和晶界的缘故，在紫外范围内表现出Urbach尾态。由于磁性离子的轨道分裂，膜的光学带隙随着3d电子的轨道占有数的增加而减小。发现在室温下超出基本吸收区出现了明显而强烈的激子跃迁。可以观察到紫外线和近红外电子跃迁，并显示出与跃迁金属掺杂的强烈关系。而且，由于不同的氧空位，氧间隙和表面形态，橙色，黄色和红色发光强烈地依赖于掺杂元素。磁测量结果表明，所有掺杂过渡金属的nc-ZnO薄膜在室温下均显示出明确的铁磁特征。特别地，掺杂有Mn的nc-ZnO膜表现出最大的饱和磁矩，这与理论上的预测是吻合的。铁磁性质可以从过渡金属掺杂的nc-ZnO材料中的磁离子掺杂，固有缺陷，界面和晶界导出。

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