Patent ID: 7972410

Claim:
A method for making magnetic nanoparticles, comprising: combining a magnetic material precursor and a first surfactant species to form a reaction solution; reacting the magnetic material precursor at a reaction temperature to form a magnetic particle core at least partially coated with the first surfactant species to form a surfactant-coated magnetic nanoparticle; growing the surfactant-coated magnetic nanoparticle to a critical size resulting in a critical susceptibility of the surfactant-coated magnetic nanoparticle to produce a critical-sized magnetic nanoparticle capable of spontaneously agglomerating at the reaction temperature; agglomerating a plurality of the critical-sized magnetic nanoparticles to form agglomerated critical-sized magnetic nanoparticles; and precipitating the agglomerated critical-sized magnetic nanoparticles to form precipitated magnetic nanoparticles.