Sr 14.06 Gd 14.63 (BO 3 ) 24 : A Gadolinium-Rich Borate with Magnetic Refrigeration Performance.

A single crystal of Sr 14.06 Gd 14.63 (BO 3 ) 24 has been successfully grown through a high-temperature solution technique with K 2 O-KF-B 2 O 3 as the flux. It crystallizes in the Pnma space group with parameters a = 22.3153(5) Å, b = 15.9087(4) Å, c = 8.7507(2) Å, and Z = 2. Sr 14.06 Gd 14.63 (BO 3 ) 24 has a three-dimensional (3D) framework built from [GdO] chains, in which the isolate [BO 3 ] 3- groups and Sr 2+ ions fill in the space of the 3D framework. The magnetic measurements revealed that the title compound exhibits a large magnetocaloric effect with the magnetic entropy change of -Δ S m = 42.2 J kg -1 K -1 at 2 K for 7 T, which is higher than that of the commercial material, Gd 3 Ga 5 O 12 (GGG), with -Δ S m of 38.4 J kg -1 K -1 under the same conditions. Moreover, the infrared spectrum (IR), UV-vis-NIR diffuse reflectance spectrum, and thermal stability were investigated.