Synthesis, crystal structure, spectrum properties, and electronic structure of a new three-borate Ba4Na2Zn4(B3O6)2(B12O24) with two isolated types of blocks: 3[3Δ] and 3[2Δ+1T]

A new barium sodium zincoborate, Ba4Na2Zn4(B3O6)(2)(B12O24), has been prepared by solid state reaction method below 750 degrees C. Single-crystal XRD analysis showed that it crystallizes in the triclinic space group P (1) over bar with a = 7.0288(14) angstrom, b = 7.0687(14) angstrom, c = 17.501(4) angstrom, alpha = 91.92(3)degrees, beta = 96.46(3)degrees, gamma = 119.72(3)degrees, Z = 1. The crystal structure exhibits complicated porous anionic layers composed of ZnO4 tetrahedra, [B3O6](3) rings with notation of 3[3 Delta], and [B12O24](12) groups built up from four BO4 tetrahedra and eight BO3 triangles with notation of 2 x {2 x (3[2 Delta + 1T])}. The anionic layers stack along c-axis, with the intralayer open channels and interlayer void spaces occupied by Na+ or Ba2+ cations to balance charge. The IR spectrum further confirmed the presence of both BO3 and BO4 groups. UV-vis diffuse reflectance spectrum revealed a band gap of about 3.13 eV. Solid-state fluorescence spectrum exhibited abroad emission band at around 540 nm. Band structure calculations indicated that it is an indirect band material with the calculated band gap of about 4.278 eV. (C) 2013 Elsevier B.V. All rights reserved.