title: UV nonlinear optical crystal Ba2[B6O9(OH)4] featuring unique chiral layers with a new B18O42 circle based on BO3 and BO4 units.
abstract: A new noncentrosymmetric polyborate, Ba(2)[B(6)O(9)(OH)(4)], has been synthesized under a hydrothermal condition. The polyborate contains chiral layers constructed by  two kinds of helical chains and also form new B(18)O(42) circles based on B(3)O(8) units [(3: Δ+2T)]. One kind of Ba atom locates in the cavity surrounded by the B(11)O(11) ring within the anion layer, and the other kind of Ba atom inserts between two adjacent layers.  UV-vis diffuse reflectance spectroscopy demonstrates that the compound has a cutoff edge below 190 nm and has a large second-harmonic generation (SHG) effect, which is approximately 3 times that of KH(2)PO(4) (KDP) and is type-I phase matchable.
authors.affiliation: Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics & Chemistry, Chinese Academy of Sciences, 40-1 South Beijing Road, Urumqi 830011, China.
authors.forename: Li
authors.initials: L
authors.lastname: Wang
authors.forename: Shilie
authors.initials: S
authors.lastname: Pan
authors.forename: Lixian
authors.initials: L
authors.lastname: Chang
authors.forename: Jianyang
authors.initials: J
authors.lastname: Hu
authors.forename: Hongwei
authors.initials: H
authors.lastname: Yu