The synthesis and characterization of nickel–copper alloy nanoparticles with a narrow size distribution using sol–gel synthesis

• NiCu alloy nanoparticles were synthesized using the sol–gel method.
• Unique etching solution was used to remove silica matrix.
• The nanoparticles can be applied for self-regulating magnetic hyperthermia.
• Synthesis allows the production of nanoparticles on a large scale.

Nickel–copper (NiCu) alloy magnetic nanoparticles with a narrow size distribution were prepared by reducing a Ni, Cu-oxide mixture in a silica matrix, obtained with a sol–gel method. In order to obtain the NiCu nanoparticles, the silica matrix was treated with an etching solution in an argon atmosphere. By selecting the nominal NiCu alloy composition of 67.5:32.5, a Curie temperature close to 65 °C was achieved. The nanoparticles were superparamagnetic with a magnetization of 8 emu/g at 293 K and exhibited a significant heating ability in an alternating magnetic field. The simplicity of the synthesis allows the preparation of NiCu alloy nanoparticles on a large scale. The method could also be used for the preparation of other mixed-alloy nanoparticles.