Structural, infrared and magnetic properties of MgAlxFe2-xO4 compounds: Effect of the preparation methods and Al substitution

摘要

Aluminum substituted magnesium ferrite MgAlxFe2-xO4 (x = 0.0, 0.2, 0.3, 0.7 and 2.0) are prepared by two commonly-used methods: Sol-gel (SG) and Solid-phase reaction (SR). Structural studies are carried out using X-ray and neutron diffraction, and FTIR techniques, and heat generation ability in the AC magnetic field is explored by the specially designed device. Diffraction patterns revealed the formation of single cubic spinel MgAlxFe2-xO4 ferrites for SG and additional MgAl2O4 phases at higher concentration of aluminum (x > 0.3) in SR samples. Structural studies are carried out using X-ray and neutron diffraction, and FTIR techniques, scanning electron microscopy (SEM) and heat generation ability in the AC magnetic field is explored by the specially designed device. This study attempts to compare both chemical methods, and to correlate the properties with Al substitution concentration. Diffraction patterns revealed the formation of single cubic spinel MgAlxFe2-xO4 ferrites for SG and additional MgAl2O4 phases at higher concentration of aluminum (x > 0.3) in SR samples FTIR was used to confirm the spinel structure, the main vibrating modes were observed to shift to higher wave number with increasing Al3+ concentration. The tetrahedral force constant (KT) increases continuously with Al3+ concentration. The morphology investigations revealed the spherical morphology of particles with some agglomeration. The heat-generation ability was enhanced with decreasing Al concentration. Upon exposure to an external alternation magnetic field of 70 kHz and intensity of 54.3 mT, specific power absorption rate (SAR) of the Magnesium ferrite aluminates. The heat generation ability of the MgAlxFe2-xO4-SR ferrites are higher than those of MgAlxFe2-xO4-SG samples. Moreover, doping element is affected to cation distribution between tetrahedral and octahedral sites. For MgAlxFe2-xO4, heat generation ability will be influenced by additional magnetic properties and cation distribution. Th