Large Magnetocaloric Effect in LiKGd(BO) Crystal Featuring Sandwich-Like Three-Dimensional Framework.

A new Gd-based borate crystal, LiKGd(BO), has been successfully obtained via the high-temperature solution method using LiO-KO-BO self-flux. It crystallizes in monoclinic space group 2/ (no. 10) with lattice parameters = 11.3454(6) Å, = 9.9881(4) Å, = 11.4467(7) Å, α = γ = 90 , β = 114.782(7) , and = 2. LiKGd(BO) exhibits an intriguing sandwich-like three-dimensional (3D) framework constructed from [Gd-B-O] layers, KO ( = 6 and 8) polyhedra, and LiO tetrahedra, in which [Gd-B-O] layers are built from two types of GdO polyhedra and triangular BO units. Magnetic measurements showed that LiKGd(BO) exhibits a large magnetocaloric effect with -Δ = 39.3 J kg K at 2.0 K for Δ = 7 T, which is slightly higher than that of the commercial gadolinium gallium garnet under the same conditions. The powder X-ray diffraction, infrared spectrum, and UV-vis-NIR diffuse reflectance spectrum were also performed to characterize LiKGd(BO). The electronic band structures, partial density of states, and refractive indices of LiKGd(BO) were investigated via the first-principle calculations.