Large magnetocaloric effect in gadolinium-rich silicate NaGd₉(SiO₄)₆O₂

Magnetic cooling has aroused great interest in cryogenic research due to its high energy efficiency. Due to the large magnetic moment and completely quenched orbital momentum, Gd-based oxides have been promising candidates for cryogenic magnetic refrigerant. In this article, the magnetic properties and magnetocaloric effect of NaGd₉(SiO₄)₆O₂ (NGSO) single crystal are investigated. The maximum magnetic entropy change of 60 J·kg⁻¹K⁻¹ is observed with the magnetic field changing from 0–7 T at 2.6 K. The large magnetic entropy change can be attributed to high metal/ligand ratio and weak exchange interaction. Particularly, due to the large density of NGSO, the volumetric entropy change is identified to be 382.8 mJ·cm⁻³K⁻¹, which surpasses most reported magnetic refrigerants in volume units. Besides, the excellent refrigerant capacity and adiabatic temperature change have been determined to be as high as 370.4 J·kg⁻¹ and 7.4 K under the applied field change of 0–7 T and 0–2 T, respectively. These performances suggest that NGSO is a promising candidate for low-temperature magnetic refrigeration applications.