Synthesis and magnetic properties of Co nanoparticles embedded in a zeolite matrix.

PABLO M. BOTTA; PAULA G. BERCOFF; HÉCTOR R. BERTORELLO; CLARA SAUX; LILIANA B. PIERELLA; JOSÉ RIVAS

San Sebastián, España

Conferencia; Trends in Nanotechnology (TNT 07); 2007

Co-HZSM-5 zeolites were prepared by wet impregnation of NH4-MFI with aqueous solution of cobalt salt to yield the desired wt % of the cation (2.8 Co wt% and 4.9 Co wt%,). The samples were dried at 110ºC and calcined at 500ºC under N2 flow (10 ml/min) and then under an oxidizing atmosphere for 12 h. Finally, these powders were reduced from room temperature to 500ºC at 5ºC/min and holding at 500ºC for 5 h, in H2 flow (5 ml/min). These samples were called reduced zeolites (CoxIR, x = 2.8, 4.9). The Co content was accurately determined by atomic absorption. Crystal structure was studied by means of X-ray diffraction in a powder diffractometer using CuKa radiation. Scanning electron micrographs (SEM) and energy dispersive spectra (EDS) were used to characterize the microstructure and elemental composition of the samples. Magnetic measurements were performed in a commercial SQUID, varying the temperature from 5 to 300 K, with applied fields ranging from 25 to 200 Oe, and at several constant temperatures with applied fields up to 5 T.