K₂Ca₄[(UO₂)(Si₂O₇)₂]: A Uranyl Silicate with a One-Dimensional Chain Structure

Abstract

A new uranyl silicate, K2Ca4[(UO2)(Si2O7)2], with a 1D chain structure has been synthesized from a solution of mixed alkali- and alkaline-earth-metal cations under hydrothermal conditions at 550 °C and 1400 bar and characterized by single-crystal X-ray diffraction and photoluminescence spectroscopy. It crystallizes in the triclinic space group P1̅ (No. 2) with a = 6.6354(2) Å, b = 6.6791(2) Å, c = 9.6987(3) Å, α = 98.324(2)°, β = 93.624(2)°, γ = 112.310(2)°, and Z = 1. Its crystal structure consists of a 1D chain of uranyl disilicate formed of corner-sharing UO6 tetragonal bipyramids and Si2O7 double groups. The adjacent chains are separated by K(+) and Ca(2+) cations. It is the first example of uranyl silicate with a 1D chain structure.

Formation of Open Framework Uranium Germanates: The Influence of Mixed Molten Flux and Charge Density Dependence in U-Silicate and U-Germanate Families

“…Two types of SBUs can be found in this structure. The first one contains a 1D chain previously observed in K 2 Ca 4 (UO 2 )­(Si 2 O 7 ) 2 which is based upon [UGe 4 ] pentamers (A - type) (Figure c). The second type of infinite chains contains A2 - type of [UGe 4 ] pentamers, shown in Figure e.…”

Colossal Dielectric Responses from the Wide Band Gap 2D-Semiconducting Amine Templated Hybrid Framework Materials

“…An extensive study of hybrid frameworks shows that, as compared to the traditional silicate, phosphate, and sulfate tetrahedra with fewer coordination sites, − organophosphonate units are the best possible sources for the organic component in such materials, with their multiple coordination sites being extremely useful toward the design of higher-dimensional hybrid frameworks with host–guest interactions. − Presently, metal organophosphonates are a well-investigated class of hybrid frameworks with their exciting structure–property relationship, − though their potential uses based upon their dielectric behavior has not been reported so far. Silver­(I) ions, by their inherent chemical nature of irregular coordination number and geometry, are best suited for isolating fascinating hybrid frameworks. − However, the amine-templated silver­(I) phosphonate frameworks have not been thoroughly investigated to date.…”

K8(K5F)U6Si8O40: An Intergrowth Uranyl Silicate

“…On the other hand, with the exception of A 2 USiO 6 (A = Rb, Cs), all of the nonmineral uranyl silicates contain isolated UO 6 polyhedra. These polyhedra are connected by 0D, − 1D, ,− or 2D ,, silicate units. A 2 USiO 6 contains 1D chains of corner-sharing UO 6 polyhedra connected into a 3D structure by Si 4 O 12 squares …”