Synthesis, structure and electronic calculation of alkali metals borate Li2Na[B5O8(OH)2]

A new alkali metals borate complex, Li2Na[B5O8(OH)(2)], has been successfully synthesized by a facile hydrothermal method. Single-crystal X-ray diffraction analysis reveals that it crystallizes in orthorhombic space group Pbcn with a = 8.919(3) angstrom, b = 9.181(3) angstrom, c = 8.416(2) angstrom, Z = 4. The crystal structure is constructed of two dimensional (2D) [(B5O8)(OH)(2)](infinity) layers, while stacking along b axis and then connected by Li+ and Na+ cations to extend to 3D framework Li2Na[B5O8(OH)(2)]. UV-vis-NIR spectrum shows that Li2Na[B5O8(OH)(2)] possesses a wide range of transparency and a UV cut-off edge below 190 nm which indicates that it may be applied in the deep ultraviolet region. The calculated band structures and the density of states indicate that Li2Na[B5O8(OH)(2)] is a direct band gap compound with a band gap of 5.68 eV. In addition, IR spectroscopy, thermal stability and theoretical calculations of Li2Na[B5O8(OH)(2)] are also reported in this work. (C) 2017 Elsevier B.V. All rights reserved.