Synthesis and Growth of Rare Earth Borates NaSrR(BO3)2 (R = Ho-Lu, Y, Sc)

NaSrR(BO₃)₂ (R = Ho-Lu, Y, Sc) compounds were obtained for the first time. Their structures exhibit disordered positions of Sr²⁺ and Na⁺ atoms while RO₆ polyhedra are connected through the BO₃ groups. Large distances between R atoms and high transparency in the range of 250-900 nm make them promising for phosphor applications. A pathway to obtain single crystals was shown by growing NaSrY(BO₃)₂ and NaSrYb(BO₃)₂ by the top seeded solution growth method with Na₂O-B₂O₃-NaF flux.

Obtaining of luminescent material based on NaBaY(BO3)2 doped with terbium and europium ions

A new luminescent material based on complex borate NaBaY(BO3)2 doped with Tb3+ and Eu3+ ions was obtained by high-temperature solid-state synthesis. Using X-ray diffraction analysis it was shown that NaBaY(BO3)2:0.07Tb3+:0.1Eu3+ crystallizes in trigonal system with the space group R-3m and isotypic with the mineral buetschliit K2Ca(CO3)2. The crystal structure of the phosphor is layered, formed from [BO3] triangles, [YO6] octahedra, [BaO9] and [NaO9] polyhedra. The calculated unit cell parameters for NaBaY(BO3)2:0.07Tb3+:0.1Eu3+ are: a=5.3510(6) Å, c=17.9338(3) Å, V=444.71(2) Å3. The luminescent properties of NaBaY(BO3)2:0.07Tb3+:0.1Eu3+ were studied.

High-Performance Magnetic Refrigerant Featuring One-Dimensional Gd-O Chains and O-Gd3 Triangles

Magnetic cooling at low temperature has attracted intensive interest in cryogenics research, which may become important as cooling medium for long-wave photon detectors to support space exploration. Here, we report a Gd-based quaternary magnetic refrigerant material, Gd₅ BSi₂ O₁₃ , containing chains of face-shared GdO₉ polyhedra and geometrically frustrated OGd₃ triangles. Magnetic measurements indicate that Gd₅ BSi₂ O₁₃ exhibits a large magnetocaloric effect (MCE) about 1.74 times that of the practical magnetic refrigerant GGG (-ΔS_m =67.0 J kg^-1  K^-1 ). We analyzed the origin of the large MCE by comparing Gd^III -containing compounds with different structures and concentrations of Gd^III .

Orthoborates LiCdRE5(BO3)6 (RE = Sm-Lu and Y) with Rare-Earth Ions on a Triangular Lattice: Synthesis, Crystal Structure, and Optical and Magnetic Properties

Single crystals of LiCdY₅(BO₃)₆ were successfully grown from a Li₂O-B₂O₃ flux, and its lanthanide homotypic compounds, LiCdRE₅(BO₃)₆ (RE = Sm-Lu), have been prepared by solid-state reaction. They crystallize in the noncentrosymmetric space group P6₅22 with cell parameters in the ranges of a = 7.0989(2)-6.9337(1) Å and c = 25.9375(1)-24.8960(6) Å. As a representative example, LiCdY₅(BO₃)₆ features a triangular lattice in the ab plane composed of three distinct crystallographic Y sites. The triangular lattices spaced with the same distance of [Formula: see text]c are further stacked to build three-dimensional frameworks by reinforcement of the isolated planar BO₃ groups and distorted LiO₄ tetrahedra. Magnetic measurements show that Eu and Sm compounds exhibit typical Van Vleck-type paramagnetism and other rare-earth borates show weak antiferromagnetic behavior. In addition, UV-vis-near-IR diffuse-reflectance and photoluminescence spectra were performed to understand the transition energy levels of active rare-earth ions and their relationships to magnetism.