Bismuth borates: One-dimensional borate chains and nonlinear optical properties

Three bismuth borates, Bi[B4O6(OH)(2)]OH (I), BiB2O4F (II), and Bi-3[B6O13(OH)] (III), were obtained in boric acid flux at low temperatures and their structures were determined by using single-crystal and powder X-ray diffraction techniques. All these three bismuth borates contain one-dimensional borate chains and crystallize in noncentrosymmetric space groups. I is a hydrated borate, crystallizing, in the space group PI with lattice constants a = 4.300(1) angstrom, b = 8.587(2) angstrom, c = 10.518(2) angstrom, alpha = 113.11(3)', 100.50(3)degrees, and beta = 90.36(3)degrees, and the borate chain consists of a 3-ring (2BO(3) + BO4) and a BO3 group. II is a fluoroborate, which crystallizes in the trigonal space group P3(2) with a = 6.7147(1) angstrom and c = 6.4688(1) angstrom, and the borate anion is a 3-fold helix chain formed by extensive linkage of three-membered borate rings (3BO(4)). III is also a hydrated borate with a structure that is closely related to 11, in which one-sixth of the borate groups are in triangular geometry (BOA which reduces the symmetry to P1, a = 6.6257(1) angstrom, b =6.6238(1) angstrom, c = 6.6541(1) angstrom, and alpha = 89.998(3)degrees, beta = 89.982(2)degrees, and gamma = 119.992(2)degrees. All these three bismuth borates exhibit nonlinear optical (NLO) properties.