LiCs2La(BO3)2 and Li3K9La3(BO3)7: new mixed alkali metal lanthanum borates with three-dimensional open frameworks and short cut-off edges

Magnesium cations as templates for the self-assembly of supramolecular luminescent {Mg@[B18φ34-35]}-clusters

Solvothermal reaction of magnesium nitrate and boron oxide in N,N-dimethylformamide produced a number of particularly complex supramolecular magnesium borates. Five topologically different types of negatively charged {Mg@[B18φ34-35]}-clusters, φ = O, OH, were observed with the magnesium cation as a core and octadecaborate anions as shells. The clusters assemble via common borate polyhedra forming 1D chains, a 2D mesoporous layer, and 3D mesoporous frameworks with an effective channel width of up to 16 Å. Topological analysis of the clusters in combination with the modular crystallography approach indicates that numerous new functional materials can be obtained by varying their assembly mode. At least one compound containing such clusters exhibits a very strong luminescence.

Inducing Large Birefringence by Enhancing Asymmetric Electron Distribution of Y-O Polyhedra

Birefringent crystals can create and control polarized light, which has crucial applications in optical communication, polarimetry, and scientific instrumentation. For most of birefringence phenomenon in borate crystals, optic anisotropy mainly...

Large Magnetocaloric Effect in Li3K9Gd3(BO3)7 Crystal Featuring Sandwich-Like Three-Dimensional Framework

A new Gd-based borate crystal, Li₃K₉Gd₃(BO₃)₇, has been successfully obtained via the high-temperature solution method using Li₂O-K₂O-B₂O₃ self-flux. It crystallizes in monoclinic space group P2/n (no. 10) with lattice parameters a = 11.3454(6) Å, b = 9.9881(4) Å, c = 11.4467(7) Å, α = γ = 90 ^o, β = 114.782(7) ^o, and Z = 2. Li₃K₉Gd₃(BO₃)₇ exhibits an intriguing sandwich-like three-dimensional (3D) framework constructed from [Gd-B-O]_∞ layers, KO_n (n = 6 and 8) polyhedra, and LiO₄ tetrahedra, in which [Gd-B-O]_∞ layers are built from two types of GdO₈ polyhedra and triangular BO₃ units. Magnetic measurements showed that Li₃K₉Gd₃(BO₃)₇ exhibits a large magnetocaloric effect with -ΔS_m = 39.3 J kg^-1 K^-1 at 2.0 K for ΔH = 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 Li₃K₉Gd₃(BO₃)₇. The electronic band structures, partial density of states, and refractive indices of Li₃K₉Gd₃(BO₃)₇ were investigated via the first-principle calculations.

A new non-centrosymmetric Gd-based borate crystal Rb7SrGd2(B5O10)3: growth, structure, and nonlinear optical and magnetic properties

A new non-centrosymmetric borate crystal, Rb7SrGd2(B5O10)3, was successfully grown via the spontaneous nucleation technique from the Rb2O-B2O3-SrO self-flux system. It crystallizes in the trigonal system space group R32 with lattice parameters a = b = 13.4975(5) Å, c = 15.3223(8) Å, α = β = 90°, γ = 120°, and Z = 3. Its three-dimensional framework is composed of isolated GdO6 and SrO6 octahedra, RbOn (n = 6 and 8) polyhedra, and [B5O10]5- clusters. Rb7SrGd2(B5O10)3 exhibits multifunctional properties, and has both moderate second harmonic generation (SHG) responses (0.5 × KDP) and paramagnetic characteristics with μeff = 8.18μB. Thermal stability, Fourier transform infrared spectroscopy, and UV-Vis-NIR diffuse reflectance spectroscopy were performed to characterize the title compound. Its electronic band structures and density of states were also investigated via first-principles calculations.