N. N. Mochenova

Potassium bromo-borate K3[B6O10]Br—A new nonlinear optical material

A new polar hexaborate, K3[B6O10]Br (space group R3m), is synthesized under hydrothermal conditions. The radical anion is composed of macallisterite hexaborate blocks 6[3Δ + 3T] formed by boron triangles and boron tetrahedra. The blocks are joined together through vertices into a [B6O10]∞∞∞2− zeolite-like framework of a new type. Large K+ cations and Br− anions are located in extended channels that are aligned parallel to rhombohedral translations of the crystal lattice. The structure of the sublattice formed by large ions consists of BrK6 bromo-centered octahedra, which are linked together through vertices into a hexagonally distorted perovskite framework. The perovskite framework is inserted into the boron-oxygen framework so that these two frameworks do not intersect. The nonlinear optical properties of powdered samples of the K3[B6O10]Br compound are investigated using the second harmonic generation method. It is found that the K3[B6O10]Br compound exhibits a high nonlinear optical activity that exceeds the activities of the majority of borate compounds and is characteristic of haloid borates of the hilgardite family.

New isoformula iodates In(IO3)3 and Sm(IO3)3 with different crystal structures: Specific structural features of I5+ compounds

AbstractNew iodates, namely, In(IO3)3 (space group R

A new modification of Ba[B5O8(OH)] · H2O, the refined structure of Ba2[B5O9]Cl · 0.5H2O, and the role of the pentaborate structural units in the formation of the quadratic optical nonlinearity

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New layer borate (Nd0.925Na0.075)Nd[B9O15(OH)2]Cl0.85 · 2.65H2O and its place in the structural systematics

) and Sm(IO3)3 (space group P21/a), are synthesized under hydrothermal conditions. The original crystal structure of the In(IO3)3 compound is determined without prior knowledge of the chemical formula. The Sm(IO3)3 compound is isostructural to the Gd(IO3)3 compound. The [IO4]3- tetrahedra with three short I-O bonds have an umbrella coordination, which is characteristic of pentavalent iodine, and form anionic radicals, such as a ring radical in the In(IO3)3 iodate, a triple helix in the isoformula compound Fe(IO3)3, a complex chain in the Sm(IO3)3 iodate, and a linear triortho group in the Sm(IO3)3·H2O compound. All radicals contain triortho groups. The structural differences are determined by different ionic radii and shapes of the coordination polyhedra of the cations (indium and iron octahedra and an eight-vertex samarium polyhedron).

Synthetic Na,Sr-carbonatoborate with a new type of pentaborate layer: The OD nature of the structure and its correlation with volkovskite, veatchites, and hilgardites

The structures of new nonaborates, (Pb,Ba)3(OH)[B9O16][B(OH)3] (space group P31c) and Ba3Na(OH)[B9O16][B(OH)4] (space group P1), synthesized under hydrothermal conditions, have been investigated. These structures differ from the structure of the previously studied nonaborate Pb3(OH)[B9O16][B(OH)3] (space group P31c) in the occupation of the zeolite nonaframework, which, in the case of the (Ba,Na) borate, contains a larger number of cations and OH groups. Despite this difference, all the structures have a high trigonal or pseudotrigonal symmetry, which suggests the existence of the structure type or the family of nonaborates. The structural similarity is violated by the presence of B(OH)41− tetrahedra instead of neutral trigonal groups B(OH)3 in channels of the (Ba,Na) borate. The latter polyhedra are characterized by a pseudomonoclinic arrangement that corresponds to the space group Cc with the true triclinic group P1. The ability of nonaborates to generate the optical second harmonic as a function of the specific features of their crystal structures is discussed.

Compound La[B5O8(OH)2] with a new type of pentaborate layer based on the 5[3T + 2Δ] block: Topology-symmetry analysis and the position in the structural system

AbstractThe structure of a new modification of the barium pentaborate β-Ba[B5O8(OH)] · H2O synthesized under hydrothermal conditions is investigated. This structure differs from the previously studied structure of the α-Ba[B5O8(OH)] · H2O compound by a shorter interlayer spacing and a higher degree of filling of the intersheet space with water molecules and barium atoms (the space group P

Crystal structure of a new synthetic calcium pentaborate, Ca2[B5O8(OH)]2 · [B(OH)3] · H2O, and modular crystal chemistry of pentaborates with polar boron-oxygen layers

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