Magnetic behavior of Co clusters embeded in a zeolite matrix

HECTOR BERTORELLO; LILIANA PIERELLA; CLARA SAUX; PAULA BERCOFF

Buenos Aires

Congreso; At the Frontiers of condensed Matter II –Magnetism, Magnetic Materials and their applications; 2004

Abstract A medium pore zeolitic material with MEL structure modified with Co cations was synthesized. It was characterized by Atomic Absorption, X-ray diffraction, Fourier transformed infrared and BET. The Co ions were introduced by ionic interchange in liquid phase followed by different thermal treatments. The magnetization M and/or magnetic susceptibility χ were measured after zero field cooling, together with magnetization as function of the applied magnetic field for several constant temperatures between 4.2 and 30 K. No blocking temperature was detected and a pure superparamagnetic behavior was obtained. M vs. T and were adjusted by Brillouin and Langevin functions obtaining the same results in both cases. Curve fitting gave an effective moment of 100 µB for the cases under study. The results are analyzed in terms of the possible cluster structure that may appear.