Growth and magnetocaloric effect of Na2Gd2(BO3)2O crystal

High-quality Na2Gd2(BO3)2O crystals have been successfully grown using the top-seeded solution growth method (TSSG), employing a Na2O − NaF − B2O3 flux system with optimal molar ratios of Na2Gd2(BO3)2O: Na2CO3: NaF: H3BO3 = 1:2:6:4. The magnetic and magnetocaloric properties were investigated including magnetic susceptibility (χ), magnetization (M), and isothermal magnetic entropy change (−ΔSm) measurements. Na2Gd2(BO3)2O exhibits a large magnetocaloric effect with a maximum − ΔSm of 41.6 J·kg−1·K−1 at 2 K and 7 T, which is higher than that of commercial Gd3Ga5O12 (GGG, −ΔSm = 38.4 J·kg−1·K−1 at 2 K and 7 T) and most other Gd3+-based borates, showing the potential application in the field of magnetic refrigeration.