Monodisperse nickel nanoparticles prepared from a monosurfactant system and their magnetic propertiesElectronic supplementary information (ESI) available: XPS of Ni nanoparticles; plot of magnetization vs. applied field. See http://www.rsc.org/suppdata/jm/b3/b303226d/

Monodisperse nickel nanoparticles around 3.7 nm were prepared by reduction of Ni(acac)2 (acac = acetylacetone) with sodium tetrahydridoborate in a monosurfactant system, in which hexadecylamine (HDA) serves as stabilizer and solvent, without any further size-selective process. The Ni particles show the characteristic of a superparamagnet with a blocking temperature of 12 K. The magnetic anisotropy distribution function of the nanoparticles has been extracted from the temperature dependence of magnetization.