Synthesis And Structure Characterization Of Novel Molten Alkali Metal Borates

In this study, two novel alkali metal borates were synthesized by the boric acid flux. Allthe structural data of the compounds were collected and analyzed by a single crystaldiffractometer. Both of the two borates were characterized by X-ray powder diffraction, IRand TG-DSC.The two compounds synthesized in this paper include:（i）NaZnB₃P₂O₁₀（OH）₂·1.17H₂O（ii）RbB₅O₇（OH）₂·H₂OBorophosphate NaZnB₃P₂O₁₀（OH）₂·1.17H₂O belongs to hexagonal crystal system andP63/m space group. Its unit cell parameters include a=1.17272（3） nm, c=1.21317（6） nm, γ=120°, V=1.44491nm³, Z=6, R₁=0.0679and wR₂=0.1566. The structure comprises a12-membered ring tunnel of hole with six BO4tetrahedrons and six PO4tetrahedrons, and a6-membered ring tunnel of hole with three ZnO₆octahedrons and three PO4tetrahedronsporous channels; and water molecules are filled in the porous channels.The compoundcomprises a ZnP₂O₁0layer composed of ZnO₆octahedron and PO4tetrahedron as well as aNaB₃O₁0layer composed of NaO₆octahedron and B₃O₆（OH）₂group, wherein the ZnP₂O₁0layer and the NaB₃O₁0layer are arranged in an ABAB mode to form a novelthree-dimensional framework structure.Pentaborate RbB₅O₇（OH）₂·H₂O belongs to the monoclinic crystal system and P₂/cspace group. Its unit cell parameters include a=0.7640（2）nm, b=0.9019（3）nm, c=1.0833（3）nm,β=103.681（5）°, V=0.7252（4） nm³, Z=2, R₁=0.0737and wR₂=0.1588. Boron-oxygen polyanionunit [B₅O₇（OH）₂]-is connected with the adjacent unit [B₅O₇（OH）₂]-by O₁atoms that forminfinite zigzag chain, which are further connected by O₁atoms and Rb+ions that form athree-dimensional chiral structure.Boric acid flux used herein is simple and easy to introduce boron atoms, which hasbeen successfully applied in the syntheses of lithium battery cathode materials. Borates thatare of12-membered rings,6-membered rings structure prepared in this paper will facilitatethe innovation of borate materials and lay a solid foundation for the development of morenovel materials with special functions.