Preparation of nanoparticle materials

A method of producing nanoparticles comprising effecting conversion of a nanoparticle precursor composition to a material of the nanoparticles, said precursor composition comprising a first precursor species containing a first ion to be incorporated into the nanoparticles and a separate second precursor species containing a second ion to be incorporated into the nanoparticles, said conversion being effected in the presence of a molecular cluster compound different from the first precursor species and the second precursor species under conditions permitting seeding and growth of the nanoparticles, wherein the molecular cluster compound and nanoparticle precursor composition are dissolved in a solvent at a first temperature to form a solution and the temperature of the solution is then increased to a second temperature which is sufficient to initiate seeding and growth of the nanoparticles on the molecular clusters of said compound.