Microwave-induced combustion synthesis of Li0.5Fe2.5−xMxO4 (M = Al, Cr, Mn) powder and their characterization

Li0.5Fe2.5−xMxO4 (M = Al, Cr, Mn) powders with small and uniformly sized particles were successfully synthesized by microwave-induced combustion, using lithium nitrate, ferric nitrate, aluminum nitrate, chromium nitrate, manganese nitrate, and carbohydrazide as the starting materials. The process takes only a few minutes to obtain as-received Al, Cr, and Mn-substituted lithium ferrite powders. The resultant powders annealed at 650 °C for 2 h and were investigated by thermogravimeter/differential thermal analyzer (TG/DTA), X-ray diffractometer (XRD), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), and thermomagnetic analysis (TMA). The results revealed that saturation magnetization and Curie temperature of Li0.5Fe2.5−xMxO4 were strongly affected by different metal ions substitution.