Cation Coordination Control of Anionic Group Alignment to Maximize SHG Effects in the BaMBO₃F (M = Zn, Mg) Series

Abstract

Two new noncentrosymmtric fluoroborates, BaZnBO(3)F and BaMgBO(3)F, have been synthesized and characterized. It is found that BaZnBO(3)F possesses a P6 space group with cell parameters of a = 5.0657(1) A, c = 4.2800(1) A, and Z = 1. The structure is built up by five coordinated trigonal bipyramidal ZnO(3)F(2) polyhedra and triangular BO(3) groups. The ZnO(3)F(2) bipyramid shares its three equatorial oxygen atoms with three separate BO(3) groups to form a ZnO(3)-BO(3) layer, and the layers are linked by the apical fluorine atoms in the third dimension. Owing to its special coordination, ZnO(3)F(2) forces its three neighboring BO(3) groups to arrange into a perfect parallel alignment in the plane to give maximum contribution to the nonlinear optical (NLO) effect. Both calculation and powder second harmonic generation tests show that its effective NLO coefficient is on about the same order as that of LiB(3)O(5). In contrast, in BaMgBO(3)F, which crystallizes in space group Cc with a = 17.614(3) A, b = 30.546(6) A, c = 8.060(2) A, and beta = 90.008(2) degrees , Mg coordinates to four oxygen and two fluorine atoms to form a severely distorted MgO(4)F(2) octahedron. It also uses four equatorial oxygen atoms, sharing with three BO(3) groups to form a MgO(4)-BO(3) layer, and again the layers are linked by the apical F atoms. Every Mg atom links with one edge-sharing and two corner-sharing BO(3) groups, leaving the BO(3) group misaligned and resulting in most of their contributions to NLO effects being canceled.

Cs2B4SiO9: A Deep‐Ultraviolet Nonlinear Optical Crystal

“…It is well-known that the property of the material is governed by its crystal structure. [35,36] For the SHG response, it mainly depends on the distortion of the structure when the compound is NCS. [37] In the structure of Cs 2 B 4 SiO 9 , there are three kinds of building units: SiO 4 tetrahedra, B 4 O 10 groups, and CsOn (n = 10, 12) polyhedra.…”

Flux growth of a potential nonlinear optical crystal BaMgBO3F

“…We have recently discovered a new compound BaMgBO 3 F (BMBF), which crystallizes in a monoclinic system with space group Cc [7]. Though the calculated nonlinear optical coefficients of BMBF were moderate with a maximum one of d 12 ¼ À0.11 pm/V, based on its expected deep-UV transmittance and relative large calculated birefringence 0.0584 [7], BMBF was thought to be a good candidate as a deep ultraviolet (DUV) NLO crystal.…”

“…Though the calculated nonlinear optical coefficients of BMBF were moderate with a maximum one of d 12 ¼ À0.11 pm/V, based on its expected deep-UV transmittance and relative large calculated birefringence 0.0584 [7], BMBF was thought to be a good candidate as a deep ultraviolet (DUV) NLO crystal. In this work, we will report the crystal growth of BMBF and studies of its thermal and NLO properties.…”

Reinvestigation and Characterization of the Magnesium Borate Fluoride Mg5(BO3)F

“…[25] MgO, MgF 2 , and H 3 BO 3 were prepared in a molar ratio of 8.8:1.2:6. Firstly, the mixtures of MgO and H 3 BO 3 at a molar ratio 8.8:6 were ground well and packed into Pt crucibles.…”