Faculty of Science, Technical University of Cluj-Napoca, 76 Victoriei Street, 430122 Baia Mare, Romania.
INCDO-INOE 2000, Research Institute for Analytical Instrumentation, 67 Donath Street, 400293 Cluj-Napoca, Romania.
Int J Mol Sci. 2022 Mar 13;23(6):3097. doi: 10.3390/ijms23063097.
This paper presents the influence of Mn substitution by Ni on the structural, morphological and magnetic properties of MnNiFeO@SiO (x = 0, 0.25, 0.50, 0.75, 1.00) nanocomposites (NCs) obtained by a modified sol-gel method. The Fourier transform infrared spectra confirm the formation of a SiO matrix and ferrite, while the X-ray diffraction patterns show the presence of poorly crystalline ferrite at low annealing temperatures and highly crystalline mixed cubic spinel ferrite accompanied by secondary phases at high annealing temperatures. The lattice parameters gradually decrease, while the crystallite size, volume, and X-ray density of MnNiFeO@SiO NCs increase with increasing Ni content and follow Vegard's law. The saturation magnetization, remanent magnetization, squareness, magnetic moment per formula unit, and anisotropy constant increase, while the coercivity decreases with increasing Ni content. These parameters are larger for the samples with the same chemical formula, annealed at higher temperatures. The NCs with high Ni content show superparamagnetic-like behavior, while the NCs with high Mn content display paramagnetic behavior.
本文研究了 Mn 被 Ni 取代对通过改进溶胶-凝胶法制备的 MnNiFeO@SiO（x=0、0.25、0.50、0.75、1.00）纳米复合材料（NCs）的结构、形态和磁性的影响。傅里叶变换红外光谱证实了 SiO 基质和铁氧体的形成，而 X 射线衍射图谱表明，在较低的退火温度下存在非晶态铁氧体，在较高的退火温度下存在高度晶态混合立方尖晶石铁氧体和次要相。晶格参数逐渐减小，而 MnNiFeO@SiO NCs 的晶粒尺寸、体积和 X 射线密度随着 Ni 含量的增加而增加，并遵循维加德定律。饱和磁化强度、剩余磁化强度、方形比、单位分子式磁矩和各向异性常数增加，而矫顽力随着 Ni 含量的增加而减小。对于具有相同化学式、在较高温度下退火的样品，这些参数更大。高 Ni 含量的 NCs 表现出超顺磁性行为，而高 Mn 含量的 NCs 表现出顺磁性行为。
