Structural, microstructure and magnetic properties of superparamagnetic MnxMg1−XFe2O4 powders synthesized by sol–gel auto-combustion method

• Published in: Journal of materials science. Materials in electronics Vol. 26; no. 2; pp. 1259 - 1267
• Main Authors: Rashad, M. M., Fayed, M. G., Sami, T. M., El-Shereafy, E. E.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.02.2015
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Materials Science; Optical and Electronic Materials; Crystallite Size; Ferrite; Oxalic Acid; Tartaric Acid; Saturation Magnetization
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-014-2535-5

Ultrafine manganese magnesium ferrites Mn x Mg 1 − x Fe 2 O 4 powders ( x  = 0.2, 0.4, 0.5, 0.6, 0.8) have been synthesized using a sol–gel auto-combustion method using tartaric acid as a fuel for the first time. The effect of synthesis conditions such as annealing temperature, Mn 2+ ion molar ratio and type of carboxylic acid on the crystal structure, microstructure and magnetic properties was investigated using X-ray diffraction, scanning electron microscopy and vibrating sample magnetometer, respectively. The results demonstrated that well crystalline single cubic spinel Mn x Mg 1 − x Fe 2 O 4 phase was formed at annealing temperature 1,200 °C for time 2 h. The crystallite size, lattice parameter ( a ) and the unit cell volume were observed to increase as the annealing temperature and the Mn 2+ content were increased. The microstructure of the formed powders was synthesis conditions dependent. The produced powders were found to be well defined cubic-like structure with high homogeneity by increasing Mn 2+ ion concentration up to 0.8. Furthermore, the change of carboxylic acid influenced the microstructure of the formed Mn x Mg 1 − x Fe 2 O 4 powders as the results of change of the amount of released carbon dioxide and water vapor during the annealing. The magnetic properties were sensitive to annealing temperature, Mn 2+ ion molar ratio, and type of carboxylic acid. Good saturation magnetization ( M s = ~47.0 emu/g) was achieved with Mn 2+ ion ratio 0.8 at annealing temperature 1,200 °C for 2 h using tartaric acid as an organic fuel whereas the maximum saturation magnetization ( M s = ~49.4 emu/g) was obtained using citric acid as a fuel at the similar conditions and Mn 2+ ion content 0.5.