The series of advanced nanocomposites consisting of Gd2O3 nanoparticles (NPs) embedded into periodic porous SiO2 matrix have been investigated with respect to their structural and magnetocaloric properties. By means of small angle neutron scattering and transmission electron microscopy, regular nanopores organized in the cubic or hexagonal superlattice have been documented. The pores are occupied by the NPs of progressive concentration within the nanocomposite series. All of the examined systems have exhibited extraordinarily high values of magnetic entropy change (up to 70 J kg−1 K−1) at low temperatures with the absence of thermal hysteresis, indicating their perspective utilization in cryogenic refrigeration. Profound analysis of magnetic entropy change data via scaling laws has been applied to the nanocomposite materials for the very first time. With the aid of scaling analysis, conclusions on magnetic properties and phase transition type have been made, even for the conditions unavailable in the laboratory.

The magnetocaloric effect (MCE) of hybrid nanostructures consisting of fine gadolinium oxide (Gd2O3) nanoparticles with diameter 7 nm and 12 nm loaded into the pores of the periodically ordered mesoporous silica with hexagonal (SBA-15) or cubic (SBA-16) symmetry were investigated. The concentration effect of the added nanoparticles (NPs) and the effect of the silica matrix dimensionality on the structural properties, magnetization M(H), magnetic entropy change ΔSM, and parameters A(T) and B(T) derived from Arrott plots were studied in four samples. Examined nanocomposites exhibited reasonable high values of magnetic entropy change ΔSM varying from 29 J/kgK established for Gd2O3@SBA-15 up to 64 J/kgK observed in Gd2O3@SBA-16 at maximal field change 5 T at low temperatures. This suggests that studied nanocomposites, where diamagnetic silica matrices serve as nanoreactors for growth of Gd2O3 nanoparticles and their symmetry strongly affect magnetic properties of whole composites, could be feasible for cryomagnetic refrigeration applications.

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