Zn x Fe1−x Fe2O4 nanoparticles (x = 0.0–0.25) were synthesized by the coprecipitation method. Their microstructure was investigated by X-ray diffraction with Rietveld refinement software, energy-dispersive X-ray spectroscopy, transmission electron microscopy, and Fourier transform infrared absorption spectroscopy. Their thermal, magnetic properties were investigated by thermogravimetric analysis and vibrating-sample magnetometer. The nanoparticles exhibited superparamagnetic properties, with a maximum saturation magnetization of 80.2 emu g−1 in H = 11 000 Oe at room temperature for sample with x = 0.20. The Zn nonmagnetic element content is related to the cation distribution in the superlattices and magnetic moment of the particles. The Zn0.15Fe0.85Fe2O4 nanoparticles were coated with polyvinyl pyrrolidone (PVP) with different PVP mass. Their core–shell structure was investigated, the results showed that their chemical stability and saturation magnetization were greater than those of pure Fe3O4. PVP has biological compatibility; thus, Fe0.85Zn0.15Fe2O4/PVP0.75 nanocomposite has the potential to be widely used in medical biology, science and technology.

No abstract

No abstract

The MnBi low temperature phase with high value and positive temperature coefficient of its coercivity has a potential for production of both the nanocomposite and hybrid permanent magnets. In this report, we present our results of investigation of fabrication of Mn 55 Bi 45 nanoparticles by using high energy ball milling method. The Mn 55 Bi 45 alloy was first arc-melted and then ball-milled for various time of 0.25 8 h in different environments of Argon, Alcohol, Petrol and Xylene. The resulted powder was subsequently annealed at temperatures of 200 and 250°C for time periods of 0.54 h in Ar gas. The fraction of the MnBi low temperature phase and the size of the particles strongly depend on the fabrication conditions. The desired MnBi nanoparticles with size of 25100 nm and coercivity ® 0 H c > 1 T can be achieved by choosing appropriate fabrication conditions.