Noncentrosymmetric salt inclusion oxides: Role of salt lattices and counter ions in bulk polarity

Pb3[O10Pb20](SiO4)4X10 (X = Cl, Br): The First Pb-Containing Halogen Silicates with Mirror-Symmetric Pseudo-Aurivillius Bilayers

Two new congruently melting Pb-containing halogen silicates, Pb3[O10Pb20](SiO4)4X10 (X = Cl, Br), have been synthesized using a high-temperature solution method. Their crystal structures were determined by single-crystal X-ray diffraction, and both compounds crystallize in the orthorhombic space group Cmca. In both structures, the mirror-symmetric bilayer composed of Pb-O polyhedra is observed for the first time in Pb-containing silicates and belongs to α-PbO derivatives and is related to the Aurivillius phase. Thermal behavior analysis, UV-vis diffuse-reflectance spectroscopy, and IR spectroscopy were also performed. The Pb3[O10Pb20](SiO4)4Cl10 matrix was doped with Eu3+ ions as a dopant, and its potential application in fluorescence was confirmed from the resulting orange-red emission.

Breaking the Inherent Interarrangement of [B3O6] Clusters for Nonlinear Optics with Orbital Hybridization Enhancement

The [B3O6] group as a prime functional unit provides borates with intrinsic properties that are modified by coordination to cations. Inherent [B3O6] cluster structures in borates exclusively made of them have a near-plane configuration, with more than 90% of them having a maximum dihedral angle of zero and the remaining ones being less than 13°. Although such an inherent configuration can produce considerable birefringence for good phase-matching ability, this is not conducive to obtaining high conversion efficiency and beam quality due to the walk-off effects in the nonlinear optical process. In this article, two new borate halides Ca2B3O6X (X = Cl and Br) were reported, in which the confinement effects of distorted halogen-centered secondary building blocks compress the existence space of [B3O6] primitives, resulting in the nonparallel arrangement between [B3O6] clusters in this series. Both compounds show large second harmonic generation effects, and more importantly, the broken inherent interarrangement of [B3O6] clusters makes them a moderate birefringence and small walk-off angle. Their moderate birefringence is due to the large angular alignment between [B3O6] clusters, resulting from the orbital hybridization between the Ca s and the O p orbitals of the terminal O atoms on [B3O6] clusters. Our model supports this viewpoint and offers guidelines for rearranging [B3O6] clusters' arrangements in borates.

A non-centrosymmetric chalcohalide synthesized through the combination of chemical tailoring with aliovalent substitution

A new non-centrosymmetric (NCS) chalcohalide, [Sr₄Cl₂][Ge₃S₉], was successfully designed and synthesized through combining chemical tailoring with aliovalent substitution strategies from the maternal [NaSr₄Cl][Ge₃S₁₀]. It can exhibit a large SHG effect (0.97 × AgGaS₂), a wide band gap of 3.71 eV, and a high LDT (∼16 × AgGaS₂). These results indicate that [Sr₄Cl₂][Ge₃S₉] may be a potential infrared nonlinear optical crystal.

Reactivity of FeMoO4 in CsCl Fluxes and Formation of the Salt-Inclusion Type of Compounds

The reactivity of FeMoO₄ in CsCl fluxes has been investigated by thermal analysis and chemical reactions in evacuated silica ampules. The products have been characterized by ex situ X-ray diffraction methods. Metathesis reactions involving CsCl lead to the formation of Cs₂Fe₂(MoO₄)₃ and the salt adduct Cs₂FeCl₄·CsCl. A side reaction has been observed, which is associated with a decomposition of [MoO₄]^2- in CsCl fluxes yielding Cs₂Mo₂O₇·CsCl, which contains the rare pyromolybdate anion, [Mo₂O₇]^2-, located in the center of a _∞²[CsCl] hetero-honeycomb arrangement. This salt-inclusion type of compound has been studied further in terms of its formation starting from Cs₂MoO₄, MoO₃, and CsCl. The intermediate adduct phase, Cs₂MoO₄·MoO₃, contains uncharged _∞¹[MoO₂O_2/2] chains that react with CsCl at elevated temperatures to Cs₂Mo₂O₇·CsCl. Furthermore, the site preference for alkaline-metal cations (K⁺, Rb⁺, and Cs⁺) has been evaluated for a mixed substitution series. In accordance with the Pearson concept, the polarizability of the respect cation outweighs any size differences for the occupancy of the salt-intergrowth motif, the honeycomb part of the structure.

Synthesis, Structure Determination, and Characterizations of a Polar Salt-Inclusion Scandium Germanate, Rb10Li3Sc4Ge12O36F

A noncentrosymmetric salt-inclusion germanate, Rb₁₀Li₃Sc₄Ge₁₂O₃₆F, was grown through spontaneous crystallization from a LiF-RbF flux. It crystallizes in the polar space group P31c with cell parameters of a = 10.7587(3) Å, c = 21.6691(10) Å, and Z = 2. Its structure features a complex 3D framework composed of helical [Ge₄O₁₂] chains from condensed [GeO₄] tetrahedra running along the c axis, which are interconnected by the [ScO₆] octahedra. Voids of the 3D net are filled with Rb⁺ ions, Li⁺ ions, and isolated trigonal-bipyramidal [Rb₃Li₂F] superalkali clusters. The title compound has a large band gap of 5.6 eV, a moderate powder second-harmonic-generation response of 0.9KDP, and an extremely small birefringence of 0.001, as was further unraveled by theoretical calculations.

Where the extraordinaries meet: a cascade of isosymmetrical superionic phase transitions and negative thermal expansion in a novel silver salt-inclusion borate halide

A new silver iodide borate, Ag3B6O10I, is presented as a promising solid-state electrolyte with a δ ↔ γ ↔ β ↔ α cascade of the isosymmetric superionic phase transitions.

Incorporation of iodine into uranium oxyhydroxide phases

Herein, we have synthesised a novel uranium oxyhydroxide (UOH) phase, Rb₂K₂[(UO₂)₆O₄(OH)₆]·(IO₃)₂, under hydrothermal conditions which intercalates IO₃^-via a hybrid salt-inclusion and host-guest mechanism. The mechanism is based on favorable intermolecular bonding between disordered Rb⁺/K⁺ and IO₃^- ions and hydroxyl and layer void positions respectively. To examine whether the intercalation may occur ubiquitously for UOH phases, the known UOH mineral phases metaschoepite ([(UO₂)₈O₂(OH)₁₂]·12H₂O), compreignacite (K₂[(UO₂)₆O₄(OH)₆]·7H₂O) and also related β-UO₂(OH)₂ were synthesised and exposed to aqueous I^- and IO₃^- for 1 month statically at RT and 60 °C in air and the solid analysed using laser ablation inductively coupled plasma mass spectroscopy. Measurements indicate intercalation can occur homogeneously, but the affinity is dependent upon the structure of the UOH phases and temperature, where higher temperatures and when the interlayer space is free of initial moieties are favoured. It was also found that after repeated washing of the UOH samples with DI water the intercalated iodine was retained. UOH phases are known to form during the oxidative corrosion of spent nuclear fuel during an accident scenario in the near field, this work suggests they may help retard the transport of radiolytic iodine into the environment during a long-term release event.

[GaF(H2O)][IO3F]: a promising NLO material obtained by anisotropic polycation substitution

A novel salt-inclusion fluoroiodate [GaF(H2O)][IO3F] derived from CsIO2F2 was ingeniously obtained through anisotropic polycation substitution. Because the catenulate [GaF(H2O)]2+ framework serves as a template for the favorable assembly of the polar [IO3F]2- groups and contributes to the nonlinear coefficient, [GaF(H2O)][IO3F] exhibits a greatly improved second-harmonic generation (SHG) effect of 10 times that of KH2PO4 (KDP) and a considerable band gap of 4.34 eV compared to the parent compound CsIO2F2 (3 × KDP, 4.5 eV). Particularly, to the best of our knowledge, [GaF(H2O)][IO3F] has the largest laser-induced damage threshold (LDT) of 140 × AgGgS2 of the reported iodates. All these results signify that [GaF(H2O)][IO3F] is a promising nonlinear optical (NLO) crystal. This work also proposes that anisotropic polycation substitution is an effective approach to optimize the SHG effect and develop excellent NLO materials.

Ba6BO3Cl9 and Pb6BO4Cl7: structural insights into ortho-borates with uncondensed BO4 tetrahedra

Two new halogen-rich ortho-borates, Ba₆BO₃Cl₉ and Pb₆BO₄Cl₇, were synthesized and characterized. Interestingly, Pb₆BO₄Cl₇ contains rare uncondensed BO₄ tetrahedra.

Targeted crystal growth of uranium gallophosphates via the systematic exploration of the UF4–GaPO4–ACl (A = Cs, Rb) phase space

The flux synthesis of a uranium gallophosphate and a uranium gallate, Cs₄[UO₂Ga₂(PO₄)₄] and Cs₂UO₂Ga₂O₅, and 4 uranium phosphates, [Rb₂Rb_3.93Cl_0.93][(UO₂)₅(PO₄)₅], Rb₁₁[(UO₂)₈(PO₄)₉], Rb_7.6[(UO₂)₈O_8.6F_0.4(PO₄)₂], and Rb₆[(UO₂)₅O₂(PO₄)₄], is reported.

Pb10O4(BO3)3I3: a new noncentrosymmetric oxyborate iodide synthesized by the straightforward hydrothermal method

A new first reported oxyborate iodide Pb₁₀O₄(BO₃)₃I₃ has been synthesized by a straightforward hydrothermal method.

BaBOF3: a new aurivillius-like borate containing two types of F atoms

A new Aurivillius-like fluorine-containing borate, BaBOF₃, featuring both structural characteristics of borate fluorides and fluorooxoborates has been synthesized.

Two halide-containing cesium manganese vanadates: synthesis, characterization, and magnetic properties

Two new halide-containing cesium manganese vanadates have been synthesized by a high-temperature (580 °C) hydrothermal synthetic method from aqueous brine solutions.

The structural diversity of halogen-centered secondary building units: two new mixed-metal borate halides with deep-ultraviolet cut-off edges

Categories of halogen-centered SBUs were investigated among borates to elaborate the role of halogen to enrich the structural diversity of borates.

Room-temperature catalytic oxidation of alcohols with the polyoxovanadate salt Cs5(V14As8O42Cl)

Herein we present some initial results demonstrating the room temperature oxidation of secondary alcohols catalyzed by the reduced salt-inclusion polyoxometalate, Cs₅(V₁₄As₈O₄₂Cl).

Na3B4O7X (X = Cl, Br): two new borate halides with a 1D Na-X (X = Cl, Br) chain formed by the face-sharing XNa6octahedra

Two new borate halides consist of a B₄O₉framework and a [Na₃Br] chain which have not been found in other alkali metal borate halides.

BaPbSi2O6·BaSO4: the first mixed anionic compound synthesized via BaSO4 salt-inclusion

A novel silicate and sulfate compound, BaPbSi₂O₆·BaSO₄, has been synthesized via BaSO₄ salt-inclusion.