This paper focuses on the synthesis and structural, optical, and magnetic characterization of Mn-doped CoFe₂O₄ nanoparticles synthesized by a simple chemical co-precipitation method. Synthesized magnetic nanoparticles were characterized by XRD, FTIR, UV-Vis, PL, TEM, VSM, and EPR spectroscopy. XRD analysis confirmed the significant reduction in the crystallite size from ∼17nm to 10nm as the Mn content is increased from 0 to 1. UV-Vis spectra confirmed that the Co–Mn ferrite is a direct bandgap magnetic material that possesses an energy gap from 3.92eV to 4.33eV. FTIR vibrational frequency observed between 468 and 548 cm−1confirmed the existence of metal–oxygen bond at tetrahedral and octahedral sites. Photoluminescence spectra confirmed the red emission of the samples from the peak at 680nm. TEM analysis suggests that the single domain of CoFe₂O₄ nanoparticles may vary between 38 and 72nm. Composition analysis confirmed the homogeneous mixing of Co, Mn Fe, and O atoms in the synthesized samples. The VSM study confirmed that Mn substitution favors transition from ferromagnetic to superparamagnetic. VSM analysis also confirmed the lessening in saturation magnetization and coercivity on Mn doping. The X-band electron paramagnetic resonance spectrum recorded at room temperature conveys that the superexchange interaction is increased with the increase in Mn concentration.

中文翻译：

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调整 Mn 掺杂 CoFe2O4 纳米粒子的晶体尺寸、能隙和磁性

本文重点研究了通过简单的化学共沉淀法合成的 Mn 掺杂 CoFe ₂ O _{4纳米粒子的合成及其结构、光学和磁性表征。}通过XRD、FTIR、UV-Vis、PL、TEM、VSM和EPR光谱对合成的磁性纳米颗粒进行表征。XRD 分析证实微晶尺寸从～17纳米到 10nm 随着 Mn 含量从 0 增加到 1。UV-Vis 光谱证实 Co-Mn 铁氧体是一种直接带隙磁性材料，其能隙为 3.92eV 至 4.33eV。在 468 和 548 之间观察到的 FTIR 振动频率厘米-1证实了在四面体和八面体位点存在金属-氧键。光致发光光谱证实了样品从 680 处的峰发出的红色光纳米。TEM 分析表明，CoFe ₂ O ₄纳米颗粒的单畴可能在 38 和 72 之间变化纳米。成分分析证实了合成样品中 Co、Mn Fe 和 O 原子的均匀混合。VSM 研究证实，Mn 取代有利于从铁磁性过渡到超顺磁性。VSM 分析还证实了锰掺杂时饱和磁化强度和矫顽力的降低。在室温下记录的 X 波段电子顺磁共振谱表明超交换相互作用随着 Mn 浓度的增加而增加。