Fabrication of magnetic nickel–tungsten–phosphorus particles by electroless deposition

Nickel–tungsten–phosphorus (NiWP) particles with diameters ranging from 100 to 300 nm were fabricated by electroless deposition on silica particles and Au seeds. TEM, SEM equipped with EDX, and SQUID were employed to characterize these particles. It is found that 70 °C is sufficient to deposit NiWP particles, in contrast to 90 °C required for NiP or NiWP deposited on planar substrates. Magnetic properties of these particles are profoundly influenced by P-contents, whereas replacement of P with W changes the particles from paramagnetic to soft-ferromagnetic nature. Curie temperatures and saturation magnetization of these particles are around 300 K and from 0.1 to 20 emu/g, respectively.