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.

Five new rubidium borates with 0D clusters, 1D chains, 2D layers and 3D frameworks

By tuning the synthetic conditions, borates with 0D clusters were transformed into a 1D chain, 2D layer and 3D framework.

Large optical polarizability causing positive effects on the birefringence of planar-triangular BO3 groups in ternary borates

The structure-property relationship of photoelectric functional materials has been recognized as a hot topic. The study of the inner link between the band gaps and birefringence of optical materials is extremely crucial for the design and creation of novel optical devices, but still remains rather unexplored. In this work, taking a series of borates with only planar-triangular BO₃ groups, α-/β-TM₃(BO₃)₂ (TM = Zn, Cd), Cd₂B₂O₅, and M₃(BO₃)₂ (M = Hg, Mg, Ca, Sr) as the research subject, the comprehensive relationship between their electronic structures and linear optical properties has been systematically investigated. Through combining experimental measurements and theoretical calculations, the effect of optical polarizability on the birefringence of these borates was clarified. Based on the present discussion, the relationship between the O (2p) bandwidth of the highest valence band and the HSE06 band gaps is opposite. Meanwhile, a method involving the determination of so-called optical permittivity Δε to evaluate the magnitude of birefringence Δn is found to be feasible. A large Δε makes a positive contribution to Δn. In addition, the experimentally measured band gaps and IR vibrations are in good agreement with theoretical results for the compounds α-Cd₃(BO₃)₂ and Cd₂B₂O₅.

Synthesis of nanoparticle-assembled Zn3(VO4)2 porous networks via a facile coprecipitation method for high-rate and long-life lithium-ion storage

A simple coprecipitation route followed by a calcination process was developed to prepare 2D hierarchical Zn₃(VO₄)₂ porous networks formed by the crosslinkage of monolayered nanoparticles. As a promising anode for lithium ion batteries, the electrochemical performance of Zn₃(VO₄)₂ was investigated. At a current density of 1.0 A g^-1, the Zn₃(VO₄)₂ porous networks could register a high reversible discharge capacity of 773 mA h g^-1 and the capacity retention was 94% after 700 cycles. Moreover, a remarkable reversible discharge capacity of 445 mA h g^-1 was achieved at a current density of 5 A g^-1 after 1200 cycles. Even at a higher current density of 10.0 A g^-1, a high reversible capacity of 527 mA h g^-1 could be delivered, which still remained at 163 mA h g^-1 after 1200 cycles. This superior performance is attributed to the unique 2D porous networks with a stable structure. This work shows a new avenue for facile, cheap, green, and mass production of zinc vanadate oxides with 2D porous hierarchical networks for next-generation energy conversion and storage devices.