Synthesis and magnetic properties of size-controlled CoNi alloy nanoparticles

► Temperature, solvent, concentration reducing agent, etc. impacted the particle size. ► The minimum size of the produced nanoparticles by liquid phase reduction was 60nm. ► The Hc of CoNi alloy nanoparticles decreased with the size increasing. ► The Ms of CoNi alloy nanoparticles increased with the size increasing. CoNi alloy nanoparticles were obtained using liquid phase reduction method. The size of particles was selected as the research index, and the impacts of experimental conditions on the particle size were investigated. These experimental conditions included reaction temperature, solvent, initial concentration, and the amount of reducing agent and surface active agent. Through the orthogonal test, the optimized process parameters of preparing CoNi alloy nanoparticles by liquid-phase reduction were determined. The size of the particles prepared on the basis of the optimum technology was 60nm. The particle size would impact the magnetic properties of CoNi nanoparticles measured by the test of hysteresis loops. The test result showed that the Hc of the CoNi alloy nanoparticles decreased and the Ms increased, with the increase of the particle size.