Rb3Na(H2C3N3O3)4·3H2O with Large Birefringence.
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ABSTRACT:
SUBMITTER: Aibibula M
PROVIDER: S-EPMC6933788 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Agardite-(Y), with a refined formula of Cu(2+) 5.70(Y0.69Ca0.31)[(As0.83P0.17)O4]3(OH)6·3H2O [ideally Cu(2+) 6Y(AsO4)3(OH)6·3H2O, hexa-copper(II) yttrium tris-(arsenate) hexa-hydroxide trihydrate], belongs to the mixite mineral group which is characterized by the general formula Cu(2+) 6 A(TO4)3(OH)6·3H2O, where nine-coordinated cations in the A-site include rare earth elements along with Al, Ca, Pb, or Bi, and the T-site contains P or As. This study presents the first structure determination of agardite-(Y). It is based on the single-crystal X-ray diffraction of a natural sample from Jote West mine, Pampa Larga Mining District, Copiapo, Chile. The general structural feature of agardite-(Y) is characterized by infinite chains of edge-sharing CuO5 square pyramids (site symmetry 1) extending down the c axis, connected in the ab plane by edge-sharing YO9 polyhedra (site symmetry -6..) and corner-sharing AsO4 tetra-hedra (site symmetry m..). Hy-droxyl groups occupy each corner of the CuO5-square pyramids not shared by a neighboring As or Y atom. Each YO9 polyhedron is surrounded by three tubular channels. The walls of the channels, parallel to the c axis, are six-membered hexa-gonal rings comprised of CuO5 and AsO4 polyhedra in a 2:1 ratio, and contain free mol-ecules of lattice water.
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Project description:The formation of different complexes in aqueous solutions is an important step in understanding the behavior of zinc chloride in water. The structure of concentrated ZnCl2 solutions is governed by coordination competition of Cl(-) and H2O around Zn(2+). According to the solid-liquid phase diagram, the title compounds were crystallized below room temperature. The structure of ZnCl2·2.5H2O contains Zn(2+) both in a tetra-hedral coordination with Cl(-) and in an octa-hedral environment defined by five water mol-ecules and one Cl(-) shared with the [ZnCl4](2-) unit. Thus, these two different types of Zn(2+) cations form isolated units with composition [Zn2Cl4(H2O)5] (penta-aqua-μ-chlorido-tri-chlorido-di-zinc). The trihydrate {hexa-aqua-zinc tetra-chlorido-zinc, [Zn(H2O)6][ZnCl4]}, consists of three different Zn(2+) cations, one of which is tetra-hedrally coordinated by four Cl(-) anions. The two other Zn(2+) cations are each located on an inversion centre and are octa-hedrally surrounded by water mol-ecules. The [ZnCl4] tetra-hedra and [Zn(H2O)6] octa-hedra are arranged in alternating rows parallel to [001]. The structure of the 4.5-hydrate {hexa-aqua-zinc tetra-chlorido-zinc trihydrate, [Zn(H2O)6][ZnCl4]·3H2O}, consists of isolated octa-hedral [Zn(H2O)6] and tetra-hedral [ZnCl4] units, as well as additional lattice water mol-ecules. O-H⋯O hydrogen bonds between the water mol-ecules as donor and ZnCl4 tetra-hedra and water mol-ecules as acceptor groups leads to the formation of a three-dimensional network in each of the three structures.
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Project description:Light traveling in time-dependent media has many extraordinary properties which can be utilized to convert frequency, achieve temporal cloaking, and simulate cosmological phenomena. In this paper, we focus on time-dependent axion-type magnetoelectric (ME) media, and prove that light in these media always has two degenerate modes with opposite circular polarizations corresponding to one wave vector , and name this effect "time circular birefringence" (TCB). By interchanging the status of space and time, the pair of TCB modes can appear simultaneously via "time refraction" and "time reflection" of a linear polarized incident wave at a time interface of ME media. The superposition of the two TCB modes causes the "time Faraday effect", namely the globally unified polarization axes rotate with time. A circularly polarized Gaussian pulse traversing a time interface is also studied. If the wave-vector spectrum of a pulse mainly concentrates in the non-traveling-wave band, the pulse will be trapped with nearly fixed center while its intensity will grow rapidly. In addition, we propose an experimental scheme of using molecular fluid with external time-varying electric and magnetic fields both parallel to the direction of light to realize these phenomena in practice.
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Project description:The title compounds, strontium perchlorate trihydrate {di-?-aqua-aquadi-?-perchlorato-strontium, [Sr(ClO4)2(H2O)3] n }, strontium perchlorate tetra-hydrate {di-?-aqua-bis-(tri-aqua-diperchloratostrontium), [Sr2(ClO4)4(H2O)8]} and strontium perchlorate nona-hydrate {hepta-aqua-diperchloratostrontium dihydrate, [Sr(ClO4)2(H2O)7]·2H2O}, were crystallized at low temperatures according to the solid-liquid phase diagram. The structures of the tri- and tetra-hydrate consist of Sr(2+) cations coordinated by five water mol-ecules and four O atoms of four perchlorate tetra-hedra in a distorted tricapped trigonal-prismatic coordination mode. The asymmetric unit of the trihydrate contains two formula units. Two [SrO9] polyhedra in the trihydrate are connected by sharing water mol-ecules and thus forming chains parallel to [100]. In the tetra-hydrate, dimers of two [SrO9] polyhedra connected by two sharing water mol-ecules are formed. The structure of the nona-hydrate contains one Sr(2+) cation coordinated by seven water mol-ecules and by two O atoms of two perchlorate tetra-hedra (point group symmetry ..m), forming a tricapped trigonal prism (point group symmetry m2m). The structure contains additional non-coordinating water mol-ecules, which are located on twofold rotation axes. O-H?O hydrogen bonds between the water mol-ecules as donor and ClO4 tetra-hedra and water mol-ecules as acceptor groups lead to the formation of a three-dimensional network in each of the three structures.
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