Ansari Sumayya M, Ghosh Kartik C, Devan Rupesh S, Sen Debasis, Sastry Pulya U, Kolekar Yesh D, Ramana C V
Department of Physics, Savitribai Phule Pune University, Pune 411007, India.
Department of Physics, Astronomy and Materials Science, Missouri State University, Springfield, Missouri 65897, United States.
ACS Omega. 2020 Jul 30;5(31):19315-19330. doi: 10.1021/acsomega.9b02492. eCollection 2020 Aug 11.
The authors report on the effect of manganese (Mn) substitution on the crystal chemistry, morphology, particle size distribution characteristics, chemical bonding, structure, and magnetic properties of cobalt ferrite (CoFeO) nanoparticles (NPs) synthesized by a simple, cost-effective, and eco-friendly one-pot aqueous hydrothermal method. Crystal structure analyses indicate that the Mn(II)-substituted cobalt ferrites, Co Mn FeO (CMFO, = 0.0-0.5), were crystalline with a cubic inverse spinel structure (space group 3 ). The average crystallite size increases from 8 to 14 nm with increasing Mn(II) content; the crystal growth follows an exponential growth function while the lattice parameters follow Vegard's law. Chemical bonding analyses made using Raman spectroscopic studies further confirm the cubic inverse spinel phase. The relative changes in specific vibrational modes related to octahedral sites as a function of Mn content suggest a gradual change of measure of inversion of the ferrite lattice at nanoscale dimensions. Small-angle X-ray scattering and electron microscopy revealed a narrow particle size distribution with the spherical shape morphology of the CMFO NPs. The zero-field-cooled and field-cooled magnetic measurements revealed the superparamagnetic behavior of CMFO NPs at room temperature. The sample with = 0.3 indicates a lower value of blocking temperature (9.16 K) with the improved (maximum) value of saturation magnetization. The results and the structure-composition-property correlation suggest that the economic, eco-friendly hydrothermal approach can be adopted to process superparamagnetic nanostructured magnetic materials at a relatively lower temperature for practical electronic and electromagnetic device applications.
作者报道了通过一种简单、经济高效且环保的一锅水热法合成的锰（Mn）取代对钴铁氧体（CoFeO）纳米颗粒（NPs）的晶体化学、形态、粒径分布特征、化学键、结构和磁性的影响。晶体结构分析表明，Mn（II）取代的钴铁氧体Co1−xMnxFeO4（CMFO，x = 0.0 - 0.5）为立方反尖晶石结构（空间群Fd3m）的晶体。随着Mn（II）含量的增加，平均微晶尺寸从8 nm增加到14 nm；晶体生长遵循指数生长函数，而晶格参数遵循维加德定律。使用拉曼光谱研究进行的化学键分析进一步证实了立方反尖晶石相。与八面体位置相关的特定振动模式的相对变化作为Mn含量的函数表明，在纳米尺度上铁氧体晶格的反演程度逐渐变化。小角X射线散射和电子显微镜显示CMFO NPs具有窄的粒径分布和球形形态。零场冷却和场冷却磁测量揭示了CMFO NPs在室温下的超顺磁行为。x = 0.3的样品显示出较低的阻塞温度（9.16 K）和改善的（最大）饱和磁化强度值。结果以及结构 - 组成 - 性能相关性表明，可以采用经济、环保的水热方法在相对较低的温度下制备超顺磁性纳米结构磁性材料，用于实际的电子和电磁器件应用。
