New synthetic methodology and magnetic properties of fcc Co-Ni nanostructured alloys embedded in KIT-6 matrix

摘要

Magnetic characteristics of nanocrystalline CoNi alloy materials embedded in silica matrix (KIT-6) have been investigated. CoNi alloys with different loading (4-12 wt%) were synthesized via a novel chemical reduction route. The materials are characterized by UV-VIS, IR, powder x-ray diffraction (XRD), transmission electron microscopy (TEM) and studied for their adsorption-desorption and magnetic properties. CoNi alloys crystallize in pure fcc phase with lattice parameters (a) and crystallite sizes in the range of 3.53(±2)-3.54(±2) A and 13.6(±1)-16.3(±1) nm, respectively. TEM microscopy studies reveal nanocrystalline nature of the materials. Enhancement of magnetic moment with the increase in loading wt% for CoNi alloys embedded in silica matrix is observed. The values of coercivity tend to decrease after dispersion in silica matrix and thereafter increase with increasing loading wt% of various CoNi loaded samples. The observed magnetic properties have been explained on the basis of size, surface effects, and dipolar interactions.