title: Iodide-Iodates M3[IO3]12·Ag4I, M = Bi, Tb, with a Framework Structure and High Second-Harmonic Generation Optical Response.
abstract: Single crystals of two new iodide-iodates, Bi3[IO3]12·Ag4I and Tb3[IO3]12·Ag4I, are synthesized in hydrothermal systems. The anionic parts in both iodide-iodates are characterized as a complex charged framework of isolated IO3umbrella-like groups and large Bi(Tb)-O polyhedra similar to those previously found in La3[IO3]12[IO3](Pb3O). Broad channels along the c-axis contain compensators: (Ag3I)2+umbrella-like groups and additional Ag+ions which form Ag44+tetrahedral clusters augmented with I-halogen. New iodates possess significantly higher second-order nonlinear optical characteristics compared to the previously known lead-containing compounds REE3[IO3]12[IO3](Pb3O), REE = La, Pr, Nd. The difference is related to the polar ordering of umbrella-like (Ag3I)2+groups in the channels in the new iodide-iodate. Additionally, planar-coordinated Ag atoms add three Ag atoms in umbrellas forming [Ag4I]3+polar clusters in the channels.
authors.affiliation: Geological Faculty, Department of Crystallography, Lomonosov Moscow State University , Leninskije Gory 1, Moscow, 119992 GSP2, Russia.
authors.forename: Elena L
authors.identifier: http://orcid.org/0000-0003-1550-4941
authors.initials: EL
authors.lastname: Belokoneva
authors.affiliation: Chemical Faculty, Laboratory of Functional Materials, Lomonosov Moscow State University , Leninskije Gory 1, Moscow, 119992 GSP2, Russia.
authors.forename: Sergey Yu
authors.initials: SY
authors.lastname: Stefanovich
authors.affiliation: Geological Faculty, Department of Crystallography, Lomonosov Moscow State University , Leninskije Gory 1, Moscow, 119992 GSP2, Russia.
authors.forename: Olga V
authors.initials: OV
authors.lastname: Dimitrova
authors.affiliation: Geological Faculty, Department of Crystallography, Lomonosov Moscow State University , Leninskije Gory 1, Moscow, 119992 GSP2, Russia.
authors.forename: Alina S
authors.initials: AS
authors.lastname: Karamysheva
authors.affiliation: Geological Faculty, Department of Crystallography, Lomonosov Moscow State University , Leninskije Gory 1, Moscow, 119992 GSP2, Russia.
authors.forename: Anatoly S
authors.initials: AS
authors.lastname: Volkov