A coordination polymer precursor approach to the synthesis of NiFe bimetallic nanoparticles within hybrid mesoporous silica

An approach to the synthesis and the organization of magnetic bimetallic NiFe nanoparticles of controlled size and composition was developed using thermolysis of the cyano-bridged Ni2+/[Fe(CN)(6)](3-) coordination polymer nanoparticles anchored within a hybrid mesostructured silica either under argon or under hydrogen atmospheres. The obtained NiFe nanoparticles were studied by high resolution transmission electronic microscopy (HRTEM), nitrogen sorption (BET), X-ray diffraction (XRD) and magnetic measurements, which reveal the presence of uniform bimetallic NiFe nanoparticles inside the silica pores. The size of these nanoparticles is controlled by the pore size of the silica used and by the size of the cyano-bridged coordination polymer nanoparticles. The magnetic measurements show a superparamagnetic behaviour of the nanoparticles with a decrease of the blocking temperature as the size of the nanoparticles decreases.