Size-dependent magnetism of EuS nanoparticles

EuS nanoparticles were synthesized by solution-phase thermolysis of the diethylammonium salt of the anionic europium dithiocarbamate complex, [Eu(S2CNEt2)(4)](-). Oleylamine and triphenylphosphine were used as surfactants to prevent nanoparticle agglomeration and stabilize particle growth. By varying the synthetic parameters such as reaction temperature, heating time, and the [surfactant]: [precursor] ratio, nanoparticles of different sizes were obtained. The size-dependent magnetic properties of these nanoparticles were studied, and it was observed that a decrease in the ferromagnetic ordering temperature occurs with decreasing particle size.