The fine-tuning of magnetic parameters and the identification of different magnetic phases are essential for the effective utilization of magnetic nanoparticles. In this work, we aim at controlling the magnetic parameters of Mg_0.5Zn_0.5Fe₂O₄ nanoparticles by varying the particle size and to determine magnetic phases using three analytical techniques having different operating time scales: VSM, ESR, and Mössbauer spectroscopy. Single-phase cubic spinel structured Mg_0.5Zn_0.5Fe₂O₄ nanoparticles were prepared by the sol-gel auto-combustion route and calcinated at 200, 300, 500, 700, and 900 °C. The cation distribution and structural parameters obtained from the Rietveld analysis had an insignificant variation with the calcination temperature. From the TEM analysis, an increase of the average particle size from 5 to 38 nm and widening of the particle size distribution with the calcination temperature were found. The saturation magnetization increased from 25.6 to 43.7 emu/g with the particle size due to the reduction in the magnetic dead layer thickness. The coercivity decreased from 128 to 31 Oe and the blocking temperature from 76 to 38 K with the particle size and these variations are explained in terms of surface anisotropy and dipolar interactions. Ferrimagnetic, superparamagnetic, and paramagnetic components of magnetization were deconvoluted by the curve fitting of room temperature VSM data. The ferrimagnetic component increased from 56% to 74% and the superparamagnetic component decreased from 37% to 20% respectively with the particle size. The ESR and Mössbauer spectroscopy also identified the ferrimagnetic and superparamagnetic components in the samples and their variations with the particle size were found to be in agreement with that of VSM. Thus, the variation of magnetic parameters in correlation with the particle size offers the possibility of fine-tuning the magnetic parameters of nanoparticles by adjusting the particle size. The deconvolution of magnetic phases using the three analytic methods revealed the coexistence of ferrimagnetic and superparamagnetic components of magnetization in Mg_0.5Zn_0.5Fe₂O₄ nanoparticles. Also, this deconvolution unveiled the particle size dependence on the emergence of inhomogeneity in magnetic phases of the samples.

磁性参数的微调和不同磁性相的识别对于有效利用磁性纳米粒子至关重要。在这项工作中，我们旨在通过改变粒径来控制Mg _0.5 Zn _0.5 Fe ₂ O ₄纳米粒子的磁参数，并使用三种具有不同工作时间尺度的分析技术确定磁相：VSM，ESR和Mössbauer光谱。单相立方尖晶石结构的Mg _0.5 Zn _0.5 Fe ₂ O ₄通过溶胶-凝胶自燃路线制备纳米颗粒，并在200、300、500、700和900°C下煅烧。从Rietveld分析获得的阳离子分布和结构参数随煅烧温度的变化不明显。通过TEM分析，发现平均粒径从5nm增加到38nm，并且随着煅烧温度，粒径分布变宽。由于磁死层厚度的减小，饱和磁化强度随粒径从25.6 emu / g增加到43.7 emu / g。矫顽力从128降低到31 Oe，结块温度从76降低到38 K，这些变化可以用表面各向异性和偶极相互作用来解释。亚铁磁性，超顺磁性，通过室温VSM数据的曲线拟合，对磁化的顺磁分量和顺磁分量进行了反卷积。亚铁磁性组分从56％增加到74％，超顺磁性组分从37％减少到20％。ESR和Mössbauer光谱仪还确定了样品中的亚铁磁性和超顺磁性成分，发现它们随粒径的变化与VSM一致。因此，与粒径相关的磁性参数的变化提供了通过调节粒径来微调纳米颗粒的磁性参数的可能性。使用三种分析方法对磁相进行反卷积揭示了Mg中磁化的亚铁磁和超顺磁分量同时存在_0.5 Zn _0.5 Fe ₂ O ₄纳米颗粒。同样，这种反卷积揭示了颗粒尺寸对样品磁性相中不均匀性的出现的依赖性。