Influence of preparation method on structural and magnetic properties of nickel ferrite nanoparticles

Nickel ferrite nanoparticles of very small size were prepared by sol-gel combustion and co-precipitation techniques. At the same annealing temperature sol-gel derived particles had bigger crystallite size. In both methods, crystallite size of the particles increased with annealing temperature. Sol-gel derived nickel ferrite particles were found to be of almost spherical shape and moderate particle size with a narrow size distribution; while co-precipitation derived particles had irregular shape and very small particle size with a wide size distribution. Nickel ferrite particles produced by sol-gel method exhibited more purity. Sol-gel synthesized nanoparticles were found to be of high saturation magnetization and hysteresis. Co-precipitation derived nickel ferrite particles, annealed at 400??C exhibited superparamagnetic nature with small saturation magnetization. Saturation magnetization increased with annealing temperature in both the methods. At the annealing temperature of 600??C, co-precipitation derived particles also became ferrimagnetic.