Peymanfar Reza, Afghahi Seyyed Salman Seyyed, Javanshir Shahrzad
Department of Chemistry, University of Science and Technology, Tehran, 16846-13114, Iran.
Department of Engineering, Faculty of Materials Science and Engineering, Imam Hossein University, Tehran, 1581618711, Iran.
J Nanosci Nanotechnol. 2019 Jul 1;19(7):3911-3918. doi: 10.1166/jnn.2019.16311.
A magnetic composite of SrAlFeO nanoparticles (NPs) and multiwalled carbon nanotubes (MWCNTs) was prepared using a modified Sol-gel method. The MWCNTs were functionalized using a mixture of sulfuric and nitric acids and then coated with SrAlFeO NPs in the presence of poly(methyl methacrylate) (PMMA) in an argon atmosphere furnace. The crystalline structure was studied by X-ray diffraction (XRD) confirming the single phase and hexagonal structure (M-type ferrite) of the SrAlFeO NPs. The magnetic properties of the as-prepared composites investigated by a vibrating sample magnetometer (VSM) revealed that the metallic magnetic NPs have greater magnetization compared to the SrAlFeO/MWCNT nanocomposite and exhibit acceptable magnetic behavior at room temperature. The maximum reflection loss of the sample having a coating thickness of 3.10 mm diameter and 30 weight percentage (wt%) of SrAlFeO/MWCNT was -44.08 dB at 9.56 GHz, possessing a bandwidth of 2.21 GHz with a microwave absorption up to 10 dB for the X-band. The comparison of the reflection loss in both the X and Ku-band frequencies of the individual components, i.e., silicone rubber, functionalized MWCNT, and SrAlFeO/silicone rubber, revealed that the synergistic effect of the components in the nanocomposite originate from a better impedance match. By reducing the thickness to 1.00 mm, the RL was reduced to -14.85 dB at 17.75 GHz possessing a bandwidth of 1.12 GHz (with a microwave absorption up to 10 dB) for the Ku-band. The microwave absorption of the sample was then studied in an anechoic chamber, and a similar result was obtained.
采用改进的溶胶-凝胶法制备了SrAlFeO纳米颗粒（NPs）与多壁碳纳米管（MWCNTs）的磁性复合材料。MWCNTs用硫酸和硝酸的混合物进行功能化处理，然后在氩气气氛炉中，在聚甲基丙烯酸甲酯（PMMA）存在的情况下，用SrAlFeO NPs进行包覆。通过X射线衍射（XRD）研究晶体结构，证实了SrAlFeO NPs的单相和六方结构（M型铁氧体）。用振动样品磁强计（VSM）研究了所制备复合材料的磁性，结果表明，与SrAlFeO/MWCNT纳米复合材料相比，金属磁性NPs具有更大的磁化强度，并且在室温下表现出可接受的磁行为。涂层厚度为3.10 mm、直径为30重量百分比（wt%）的SrAlFeO/MWCNT样品在9.56 GHz时的最大反射损耗为-44.08 dB，在X波段具有2.21 GHz的带宽，微波吸收高达10 dB。对各组分（即硅橡胶、功能化MWCNT和SrAlFeO/硅橡胶）在X和Ku波段频率下的反射损耗进行比较，结果表明，纳米复合材料中各组分的协同效应源于更好的阻抗匹配。将厚度减小到1.00 mm时，在Ku波段17.75 GHz处，RL降低到-14.85 dB，带宽为1.12 GHz（微波吸收高达10 dB）。然后在消声室中研究了样品的微波吸收情况，得到了类似的结果。
