Abstract Lanthanum (La3+ ions) doped magnesium ferrite nanoparticles i.e. MgLaxFe2−xO4 (x = 0, 0.05, 0.075, 0.1, 0.125) have been prepared using sol-gel technique. These as-prepared nanomagnetic particles were characterized by using X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), High resolution field emission scanning electron microscopy (HRFESEM) with energy dispersive spectroscopy (EDS), Transmission electron microscopy (TEM) and Vibrating sample magnetometer (VSM) techniques. X-ray diffraction analysis reveal that the samples are single phase cubic spinel crystals with size 12–15 nm. Lattice parameter increases with the increase in La3+ ion concentration. The induced strain calculated from Williamson-Hall plots shows that strain decreases from x = 0.0 to x = 0.075 and then increases from x = 0.1 to x = 0.125. FTIR spectra show that Fe O stretching vibration peaks of octahedral (FeO6) and tetrahedral (FeO4) group broadness increases with lanthanum content due to gradual decrease in the grain size. These variations are attributed to lattice deformation induced by interparticle interactions, cation distribution, and La3+ ions concentration in the spinel structured samples. SEM micrographs revealed the existence of superfine particles and agglomerated patterns for higher La3+ ion content. The average particle size obtained from TEM images are in close agreement with the crystallite size calculated from the XRD patterns. The magnetic studies exhibited the saturation magnetization, retentivity, anisotropy constant and magnetic moment of the particles decrease with increasing La3+ ions concentration indicating the superparamagnetic nature of lanthanum doped magnesium ferrite samples.

中文翻译：

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La 3+ 离子掺杂对用于微波吸收应用的镁纳米铁氧体物理性能的影响

摘要 使用溶胶-凝胶技术制备了镧（La3+ 离子）掺杂的镁铁氧体纳米颗粒，即 MgLaxFe2-xO4 (x = 0, 0.05, 0.075, 0.1, 0.125)。通过使用 X 射线衍射仪 (XRD)、傅里叶变换红外光谱 (FTIR)、具有能量色散光谱 (EDS) 的高分辨率场发射扫描电子显微镜 (HRFESEM)、透射电子显微镜 (TEM) 对这些制备的纳米磁性颗粒进行表征和振动样品磁强计 (VSM) 技术。X 射线衍射分析表明样品为单相立方尖晶石晶体，尺寸为 12-15 nm。晶格参数随着 La3+ 离子浓度的增加而增加。从 Williamson-Hall 图计算的诱导应变显示应变从 x = 0.0 减小到 x = 0.075，然后从 x = 0.1 增加到 x = 0.125。FTIR光谱表明，由于晶粒尺寸逐渐减小，八面体（FeO6）和四面体（FeO4）基团的Fe O伸缩振动峰的宽度随着镧含量的增加而增加。这些变化归因于尖晶石结构样品中颗粒间相互作用、阳离子分布和 La3+ 离子浓度引起的晶格变形。SEM 显微照片揭示了存在超细颗粒和团聚图案，以获得更高的 La3+ 离子含量。从 TEM 图像获得的平均粒径与从 XRD 图案计算的微晶尺寸非常一致。磁性研究显示饱和磁化强度、保持力、