Magnetic, magnetocaloric and optical properties of nano Gd3Ga5O12 garnet synthesized by citrate sol-gel method

Gd3Ga5O12(GGG) nanoparticles with an average size around 50 nm were synthesized via citrate sol-gelmethod. Rietveld refinement confirmed the formation of a single-phase garnet structure. The optical propertiescharacterized by UV-Vis absorption and photoluminescence spectra, exhibited bands centered at 300 nm and436 nm, respectively. Magnetic measurements revealed paramagnetic behaviour above 15 K, as evidenced bythe modified Curie-Weiss fitting with an effective magnetic moment of 13.86μB per formula unit (F. U.).Arrott plots confirmed a second-order nature of the magnetic phase transition. Notably, the GGG nanoparticlesdisplayed a significant magnetocaloric effect (MCE), with a maximum magnetic entropy change (-∆SM) of14.2 Jkg−1K−1at 3.5 K under a 5 T field. These findings highlight the potential of GGG nanoparticles asrefrigerants for low temperature magnetic refrigeration applications.