Effects of pH and citric acid content on the structure and magnetic properties of MnZn ferrite nanoparticles synthesized by a sol–gel autocombustion method

• MnZnFe2O4 nanoparticles were synthesized by the sol–gel autocombustion technique at different pHs and citric acid to metal nitrate (CA/MN) molar ratios.
• The single phase MnZn ferrite was achieved directly without any post-calcination using pH=7 and CA/MN molar ratio=0.5.
• Single phase nanoparticles exhibited partially inverse spinel structures.
• Magnetization was correlated to the inversion factor and crystallite size.

MnZn ferrite nanoparticles have been synthesized by a sol–gel autocombustion technique with different pHs of 0, 5 and 7 and different citric acid to metal nitrate (CA/MN) molar ratios of 0.25, 0.5 and 1. The crystallite size, microstructure and magnetic properties were studied using X-ray diffraction, scanning electron microscopy and vibrating sample magnetometry methods. The results showed that the single phase MnZn ferrite could be achieved directly without any post-calcination using pH of 7 and CA/MN molar ratio of 0.5. MnZn ferrite nanoparticles prepared by pH=7 and CA/MN=0.5 with the crystallite size of 39 nm exhibited saturation magnetization of 20.9 emu/g and coercivity of 44 Oe.