In this paper, nanocrystalline Mg-ferrites have been synthesized by the low-cost sol-gel auto-combustion method using iron and magnesium nitrates as starting materials. The as-prepared sample was annealed at temperatures of 200°C, 400°C, 600°C, 800°C, and 1000°C in an air atmosphere to investigate the effect of annealing temperature on the physical properties. The structural and magnetic properties of the annealed ferrites were studied using x-ray diffraction, Fourier transform infrared (FTIR) and Raman spectroscopy, and vibrating-sample magnetometer. The crystalline size of the nano-crystallites increased from 12 nm to 51 nm with an increase in annealing temperature from 200°C to 1000°C. Raman spectroscopy measurements revealed the presence of a spinel structure where A_1g and E_g modes occur along different bond lengths of Fe/Mg-O, due to different ionic radii of Mg⁺² and Fe⁺³ ions. The two prominent vibration frequency peaks along different bond lengths for the cubic spinel materials were confirmed using the FTIR spectra. The saturation magnetization was found to increase from 0.71 μ_B/f.u. to 1.16 μ_B/f.u. with increasing annealing temperature from 200°C to 1000°C. The magnetization results show that the magnetic properties of the nanocrystalline Mg-ferrites improved with annealing temperature.

本文以硝酸铁和硝酸镁为原料，通过低成本的溶胶-凝胶自燃法合成了纳米晶镁铁氧体。制备的样品在空气气氛中在 200°C、400°C、600°C、800°C 和 1000°C 的温度下退火，以研究退火温度对物理性能的影响。使用 X 射线衍射、傅里叶变换红外 (FTIR) 和拉曼光谱以及振动样品磁强计研究了退火铁氧体的结构和磁性能。随着退火温度从 200°C 增加到 1000°C，纳米微晶的晶体尺寸从 12 nm 增加到 51 nm。拉曼光谱测量显示存在尖晶石结构，其中 A _1g和 E _g由于 Mg ⁺²和 Fe ⁺³离子的离子半径不同，模式沿 Fe/Mg-O 的不同键长发生。使用 FTIR 光谱证实了立方尖晶石材料沿不同键长的两个突出的振动频率峰。发现随着退火温度从 200°C 增加到 1000°C ，饱和磁化强度从 0.71 μ _B /fu 增加到 1.16 μ _B /fu。磁化结果表明纳米晶Mg-铁氧体的磁性能随着退火温度的提高而提高。