Irfan H, Ezhil Vizhi R
Materials Research Laboratory, Department of Physics, School of Advanced Sciences, Vellore Institute of Technology, Vellore, Tamil Nadu 632014, India.
Nanotechnology. 2020 Oct 2;31(40):404001. doi: 10.1088/1361-6528/ab9260. Epub 2020 May 12.
BaSrFeO/YFeO (BSFO/YIG) nanocomposite ferrite with hard (BSFO) and soft (YIG) magnetic phases, were prepared by the two-step co-precipitation method. The soft magnetic phase was introduced in different weight ratios (x= 0.0, 0.1, 0.2, 0.3, 0.4 and 1) in the (1-x)BaSrFeO/(x)YFeO nanocomposite ferrites. The structural, morphological and magnetic properties of nanocomposite ferrites were analyzed by x-ray diffraction (XRD), high-resolution transmission electron microscope (HR-TEM) and room temperature vibrational sample magnetometer (VSM). The presence of the hard and soft phase have been confirmed without any secondary phase from the XRD analysis, indicating the formation of nanocomposite ferrite. The crystallite size is found to be in the range of 45-55 nm calculated by Scherrer's formula. The HR-TEM revealed hexagonal platelets of BSFO with YIG particles with an average particle size of 90 nm formed at the surface of the (0.9)BSFO/(0.1)YIG nanocomposite. The room temperature magnetic properties of the nanocomposite, such as saturation magnetization (M), squareness ratio (M/M), coercivity (H) and nucleation field (H were evaluated by employing VSM. The magnetic measurements have displayed an enhancement in coercivity and magnetization for (0.9)BSFO/(0.1)YIG. Compared with pure BSFO, the optimized (0.9)BSFO/(0.1)YIG nanocomposite showed 57% enhancement in energy product (BH), indicating that the nanocomposite possessed excellent exchange coupling. To investigate the exchange coupling between the hard and soft magnetic phases, dM/dH values were plotted using the demagnetization curves which indicated the effective exchange coupling effect between the hard and soft phases.
采用两步共沉淀法制备了具有硬磁相（BSFO）和软磁相（YIG）的BaSrFeO/YFeO（BSFO/YIG）纳米复合铁氧体。在（1-x）BaSrFeO/（x）YFeO纳米复合铁氧体中，以不同的重量比（x = 0.0、0.1、0.2、0.3、0.4和1）引入软磁相。通过X射线衍射（XRD）、高分辨率透射电子显微镜（HR-TEM）和室温振动样品磁强计（VSM）对纳米复合铁氧体的结构、形态和磁性进行了分析。XRD分析证实了硬磁相和软磁相的存在，且无任何次生相，表明形成了纳米复合铁氧体。通过谢乐公式计算得出微晶尺寸在45-55nm范围内。HR-TEM显示，在（0.9）BSFO/（0.1）YIG纳米复合材料表面形成了平均粒径为90nm的YIG颗粒与BSFO的六角形片晶。采用VSM对纳米复合材料的室温磁性进行了评估，如饱和磁化强度（M）、矩形比（M/M）、矫顽力（H）和成核场（H）。磁性测量结果表明，（0.9）BSFO/（0.1）YIG的矫顽力和磁化强度有所增强。与纯BSFO相比，优化后的（0.9）BSFO/（0.1）YIG纳米复合材料的能量积（BH）提高了57%，表明该纳米复合材料具有优异的交换耦合性能。为了研究硬磁相和软磁相之间的交换耦合，利用退磁曲线绘制了dM/dH值，表明硬磁相和软磁相之间存在有效的交换耦合效应。
