Effect of Aluminum Doping on the Structural and Magnetic Properties of Mg-Mn Ferrite Nanoparticles Prepared by Coprecipitation Method

A series of Al-substituted Mg-Mn ferrite powders with composition Mg Mn-0.8 Al-0.2 (x) Fe (2-x) O (4) (x = 0.0, 0.1, 0.2, 0.3, 0.4) were synthesized with nanosized powders through the coprecipitation method. These powders were annealed at 1250 (a similar to) for 3 h. Samples were characterized by X-ray diffraction (XRD) technique, field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), alternating gradient force magnetometer (AGFM), Curie temperature measuring device, and microwave vector network analyzer (VNA). XRD patterns confirmed that all compositions show a single-phase cubic spinel structure. The FESEM images clearly showed the crystalline structure, and EDS patterns confirm the compositional formation of the synthesized compositions. The room temperature saturation magnetization increased for x = 0.1 and then decreased for further increase in Al substitution. Curie temperature was found to be dependent on the Al concentration, and it decreased due to a decrease in the number of superexchange interactions between Fe (3+) ions in the tetrahedral and octahedral sites. VNA studies indicated a reflection loss of -32 dB at 3.2 GHz for an absorber thickness of 10.8 mm for x = 0.2 sample and with a broad bandwidth up to 2 GHz. Mg Mn-0.8 Al-0.2 (x) Fe (2-x) O (4) ferrite may be attractive candidates for electromagnetic wave absorption materials at microwave S band (2-4 GHz) frequencies commercially.