•PEG6000 was introduced during the preparation of MnZn ferrite nanoparticles.•The PEG6000 greatly mitigated the aggregation of the MnZn ferrite nanoparticles.•The PEG-containing samples presented saturated magnetization higher than the bare one.In this paper, PEG6000 was used as a surfactant to prevent the MnZn ferrite nanoparticles from aggregation. Introduction of PEG6000 didn’t affect structure of the products, but modified their dispersion state and decreased their particle size. Furthermore, saturated magnetization of the MnZn ferrite nanoparticles increased with an increase in the PEG6000 content, and presented the maximum of 110.3 emu/g at the PEG6000 content of 0.006 mol/l. This value is about 40% higher than that without any PEG6000, and almost the highest one reported to date for the MnZn ferrite nanoparticles. Hence the obtained results proved that the PEG6000 was a powerful surfactant to improve magnetic properties of the MnZn ferrite nanoparticles.Introduction of PEG6000 greatly mitigated the aggregation of the MnZn ferrite nanoparticles, and increased their saturated magnetization.Download high-res image (67KB)Download full-size image