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-gel method. Rietveld refinement confirmed the formation of a single-phase garnet structure. The optical properties characterized by UV-Vis absorption and photoluminescence spectra, exhibited bands centered at 300 nm and 436 nm, respectively. Magnetic measurements revealed paramagnetic behaviour above 15 K, as evidenced by the modified Curie-Weiss fitting with an effective magnetic moment of 13.86 μB per formula unit (F.U.). Arrott plots confirmed a second-order nature of the magnetic phase transition. Notably, the GGG nanoparticles displayed a significant magnetocaloric effect (MCE), with a maximum magnetic entropy change (-ΔSM) of 14.2 Jkg-1K-1 at 3.5 K under a 5 T field. These findings highlight the potential of GGG nanoparticles as refrigerants for low temperature magnetic refrigeration applications.