Ordered Nanoporous Silica Modified with Nanoparticles of Lanthanide Oxides

Lanthanide oxide nanoparticles were encapsulated inside of pores of highly ordered periodic silica of SBA15 type with hexagonal symmetry. The magnetic properties of such nanoperticles were investigated. The structural characterization using the SAXS, XANES, XRD, and $N_{2}$ adsorption measurements showed the presence of lanthanide oxides of $Ln_{2}O_{3}$ type (Ln=La, Pr, Nd, Gd, Eu), with the size of about 5 nm, incorporated in nanoporous channel system. Their magnetic properties, studied by SQUID apparatus, showed the weak antiferromagnetic ordering at 2 K in the nanocomposites $Gd_{2}O_{3}$@SBA15, $Pr_{2}O_{3}$@SBA15 and $Nd_{2}O_{3}$@SBA15. This behaviour of the nanoparticles is caused by blocking process of magnetic moments, which at 300 K exhibit the superparamagnetism, evidenced from ZFC/FC magnetization.