Magnetic properties of EuS nanoparticles synthesized by thermal decomposition of molecular precursors

Europium(II) sulfide nanoparticles with an average particle size of 5.5 nm and a narrow size distribution were synthesized by the direct and facile thermal decomposition of a molecular precursor Eu(Phen)(Ddtc)(3) (Phen = 1,10- phenanthroline, Ddtc = diethyldithiocarbamate) at the relatively low temperature of 200 degrees C. Compared with EuS samples of 50 - 120 nm in size, which show bulk ferromagnetic ordering, the EuS nanocrystals of 5 - 6 nm in size show a cluster glass-like behavior. Moreover, a quasi-ferrimagnetic behavior was observed in the smallest EuS sample upon oxidation of the surface.