Dawn Riya, Tjiu Weng Weei, Aabdin Zainul, Faizal Ferry, Panatarani Camellia, Joni I Made, Akhtar Waseem, Kumar Kundan, Rahaman Ariful, Chandra Girish, Kandasami Asokan, Amemiya Kenta, Singh Vijay Raj
Department of Physics, Central University of South Bihar, Gaya824236, India.
Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis #08-03, 138634Republic of Singapore.
Langmuir. 2023 Oct 3;39(39):13807-13819. doi: 10.1021/acs.langmuir.3c01222. Epub 2023 Sep 21.
In this study, magnetic FeO nanoparticles (NPs) were dispersed uniformly by varying the thickness of the SiO coating, and their electronic and magnetic properties were investigated. X-ray diffraction confirmed the structural configuration of monophase inverse-spinel FeO NPs in nanometer size. Scanning electron microscopy revealed the formation of proper nonporous crystallite particles with a clear core-shell structure with silica on the surface of FeO NPs. The absorption mechanism studied through the zeta potential indicates that SiO-coated FeO nanocomposites (SiO@FeO NCs) possess electrostatic interactions to control their agglomeration in stabilizing suspensions by providing a protective shield of amorphous SiO on the oxide surface. High-resolution transmission electron microscopy images demonstrate a spherical morphology having an average grain diameter of ∼11-17 nm with increasing thickness of SiO coating with the addition of a quantitative presence and proportion of elements determined through elemental mapping and electron energy loss spectroscopy studies. Synchrotron-based element-specific soft X-ray absorption spectroscopy and X-ray magnetic circular dichroism (XMCD) techniques have been involved in the bulk-sensitive total fluorescence yield mode to understand the origin of magnetization in SiO@FeO NCs. The magnetization hysteresis of FeO was determined by XMCD. At room temperature, the magnetic coercivity () is as high as 1 T, which is about 2 times more than the value of the thin film and about 5 times more pronounced than that of NPs. For noninteracting single-domain NPs with the spread from 1 to 3 T, the Stoner-Wohlfarth model provided an intriguing explanation for the hysteresis curve. These curves determine the different components of Fe oxides present in the samples that derive the remnant magnetization involved in each oxidation state of Fe and clarify which Fe component is responsible for the resultant magnetism and magnetocrystalline anisotropy based on noninteracting single-domain particles.
在本研究中，通过改变SiO涂层的厚度将磁性FeO纳米颗粒（NPs）均匀分散，并对其电子和磁性进行了研究。X射线衍射证实了纳米尺寸单相反尖晶石FeO NPs的结构构型。扫描电子显微镜揭示了在FeO NPs表面形成了具有清晰核壳结构且表面有二氧化硅的致密无孔微晶颗粒。通过zeta电位研究的吸收机制表明，SiO包覆的FeO纳米复合材料（SiO@FeO NCs）具有静电相互作用，通过在氧化物表面提供非晶SiO的保护屏蔽来控制其在稳定悬浮液中的团聚。高分辨率透射电子显微镜图像显示，随着SiO涂层厚度的增加，平均粒径约为11-17 nm的球形形态，同时通过元素映射和电子能量损失光谱研究确定了元素的定量存在和比例。基于同步加速器的元素特异性软X射线吸收光谱和X射线磁圆二色性（XMCD）技术已用于体敏感总荧光产率模式，以了解SiO@FeO NCs中磁化的起源。FeO的磁化滞后由XMCD测定。在室温下，磁矫顽力（）高达1 T，约为薄膜值的2倍，比NPs的值明显高约5倍。对于具有1至3 T 范围的非相互作用单畴NPs，斯托纳-沃尔法斯模型对磁滞回线提供了有趣的解释。这些曲线确定了样品中存在的不同Fe氧化物成分，这些成分导致了Fe各氧化态中涉及的剩余磁化，并基于非相互作用单畴颗粒阐明了哪种Fe成分对合成磁性和磁晶各向异性负责。
