Cd8(BO3)4SiO4: Metal Cation Inducing the Formation of Isolated [BO3] and [SiO4] Units in Borate Silicate

The first compound of cadmium-borate silicate Cd8(BO3)4SiO4, crystallizing in space group P42/n (no. 86), has been successfully synthesized by the conventional high-temperature solution method and melts congruently. The zero-dimensional anionic groups of Cd8(BO3)4SiO4 are isolated [BO3] triangles and isolated [SiO4] tetrahedra which are filled in the framework formed by [CdO6] polyhedra. It has a moderate birefringence (Δn = 0.053 at 546 nm), which is measured by experiment and evaluated by first-principles calculations; meanwhile, the source of birefringence is revealed through the response electronic distribution anisotropy method. The UV-vis-NIR diffuse reflectance spectrum indicates that Cd8(BO3)4SiO4 possesses a wide optical transparency range, with a UV cutoff edge at about 254 nm. This work enriches the structure chemistry of borate silicates, and we discussed the possible methods for the exploration and synthesis of novel optical crystals possessing zero-dimensional anionic groups in the borate silicate system.

K5[B3O3F4(OH)]2(NO3): the first hydroxyfluorooxoborate-nitrate with a short ultraviolet cutoff edge and large birefringence

The first hydroxyfluorooxoborate-nitrate mixed anion compound, K5[B3O3F4(OH)]2(NO3), was synthesized by the solution evaporation method. It displays a unique structure built by K+ cations, the hydroxylated and fluorinated six-membered ring [B3O3F4(OH)] and [NO3] groups. It possesses a band gap of 5.68 eV derived from the diffuse reflectance spectrum, which corresponds to an ultraviolet cutoff edge of 218 nm. First-principles calculations show that it has a large birefringence of 0.095 at 532 nm and the result of the response electron distribution anisotropy method indicates that all three anion groups contribute positively to the birefringence, verifying the synergic contributions from the multiple anion groups.

High-pressure synthesis of borate-nitrates: crystal structure of M 3B7O13(NO3) (M = Co2+, Ni2+, Cu2+, Zn2+, Cd2+)

The orthorhombic nitrate-boracites with the sum formula M 3B7O13NO3 (M = Co2+, Ni2+, Cu2+, Zn2+, Cd2+) were synthesized in a Walker-type multianvil apparatus under high-pressure/high-temperature conditions of 6 GPa and 800 °C, respectively. The crystal structures of the five isotypic substances, which crystallize in the space group Pca21, were determined via single-crystal X-ray diffraction and the structural features of the incorporated nitrate anions are discussed.

Two lead borate-nitrates with anion-centered [OPb4] tetrahedra and two types of π-conjugated planar units showing large birefringence

Two lead borate-nitrates Pb₆O₄(BO₃)(NO₃) and Pb₆O₂(BO₃)₂(NO₃)F were obtained by the high-temperature flux method. Interestingly, their crystal structure consists of anion-centered [OPb₄] tetrahedra and π-conjugated BO₃ and NO₃ units. The first principles calculations indicate that both compounds show large birefringence.

Ba2B5O8(OH)2(NO3)·3H2O: the design of an alkaline earth metal borate-nitrate optimized from a hydroxylic borate

The first alkaline earth metal borate-nitrate, namely Ba₂B₅O₈(OH)₂(NO₃)·3H₂O (BBNOH), has been synthesized by the hydrothermal method. BBNOH crystallizes in the space group of P2₁/c and shows two-dimensional (2D) ²_∞[B₅O₈(OH)₂]^3- borate anion layers, and the hydrated barium cations and the [NO₃]^- anions are located between the layers. The process of optimizing the structure of Ba₂B₅O₈(OH)₂OH to BBNOH has been discussed. The first principles calculation has been used to calculate the birefringence of Ba₂B₅O₈(OH)₂(NO₃)·3H₂O, and the value is 0.033@1064 nm, which is mainly originated from the borate anions and the π conjugated [NO₃]^- anions.

Where the extraordinaries meet: a cascade of isosymmetrical superionic phase transitions and negative thermal expansion in a novel silver salt-inclusion borate halide

A new silver iodide borate, Ag3B6O10I, is presented as a promising solid-state electrolyte with a δ ↔ γ ↔ β ↔ α cascade of the isosymmetric superionic phase transitions.

The First High-Pressure Chromium Oxonitridoborate CrB4 O6 N-an Unexpected Link to Nitridosilicate-Chemistry

CrB₄O₆N crystallizes in the non‐centrosymmetric space group P6₃mc (no. 186) with the lattice parameters a=5.1036(1), c=8.3519(3) Å, and a volume of 188.40(1) ų. It was synthesized in a high‐pressure/high‐temperature experiment at 7 GPa and 1673 K and represents the first high‐pressure oxonitridoborate. It is built up of starlike‐shaped entities of four BO₃N tetrahedra, connected via one common nitrogen atom that resembles the fourfold‐coordinated nitrogen atoms in the homeotypic nitridosilicates MYbSi₄N₇ (M=Sr, Ba). Building up a network with channels that contain the Cr³⁺ ions, CrB₄O₆N contains for the first time a tetrahedral building unit in contrast to trigonal planar B(O/N)₃ entities in all other known oxonitridoborates. The structural relations as well as the results of spectroscopic measurements and calculations on the chromium oxonitridoborate are discussed.

A new acentric borate-nitrate Cs3B8O13(NO3) with interpenetrating porous 3D covalent and ionic lattices

A new acentric borate-nitrate Cs3B8O13(NO3) was synthesized by a molten salt method which consists of interpenetrating porous 3D covalent [B8O13]∞ and ionic [(NO3)Cs3]∞ lattices. It shows low ultraviolet cut-off edge (202 nm) and phase-matching second harmonic generation (SHG) intensity (0.7 KDP @1064 nm). First principles calculations showed that the main source of SHG is the cooperation of the B-O and [NO3]- groups.