Influence of pH on the physical and electromagnetic properties of Mg–Mn ferrite synthesized by a solution combustion method

• Mg–Mn ferrites were synthesized by a solution combustion method with different pH.
• Auto-combustion process resulted in the formation of single phase spinel ferrite.
• An increase of pH improves the crystallinity of the Mg–Mn ferrite nanoparticles.
• pH variation has influence on phase formation and morphology of the ferrite.

The synthesis of nano-crystalline Mg–Mn ferrites by a solution combustion method using citric acid and ammonia was investigated by varying the pH of the precursor solution, which played an important role in controlling the morphology of the synthesized powders. The phase formation, microstructure and electromagnetic properties were studied using X-ray diffraction, scanning electron microscopy, impedance analyzer and vibrating sample magnetometer. Single phase pure spinel Mg–Mn ferrite powders were obtained for all the samples at different pH (< 1, 3, 5, 7, 9). The results showed that an increase of pH improves the crystallinity of the Mg–Mn ferrite nanoparticles. The average grain size of sintered samples was found to decrease from 2 μm to 0.5 μm with increasing pH values from pH < 1 to pH 9, respectively. The dielectric constant of the samples with different pH is in the range of 7–12 from frequencies of 1 MHz to 1 GHz. The highest saturation magnetization (30.04 emu/g) was obtained for the sample with pH < 1.