678 research outputs found

    Preparation and characterization of templated borophosphates and metalloborophosphates

    Get PDF
    The new borophosphates described here were synthesized under mild hydrothermal conditions (170 oC or 220 oC). Powder and single crystal X-ray diffraction were employed to determine and refine the crystal structures. DTA-TG methods were used to analyze the thermal stability. High temperature powder X-ray diffraction (HT-XRD) was applied to study the thermal behavior of products and identify the intermediate phase during the decomposition. Chemical analyses were performed to quantitatively determine the chemical composition. Magnetic properties of the compounds were investigated. 19F MAS NMR was used to check the number of fluorine positions in the crystal structure. The following compounds were prepared and characterized: (C2H10N2)[BPO4F2](C6H14N2){Zn[ZnB2P4O15(OH)2]¡P(C6H13N2)Cl} (zndabcocl) (C3H12N2){Mn[B2P3O12(OH)]} (DAP-Mn) and (C4H12N2){Mn[B2P3O12(OH)]} (PIP-Mn) (C3H12N2){FeIII6(H2O)4[B4P8O32(OH)8]}(C3H12N2)2{VIII2VIV3B2P8O38H8} (dapvbpo) K3[B5PO10(OH)3](C2H10N2)[BPO4F2] is the first fluorine-substituted borophosphate and the first borophosphate with crystal structure closely related to the pyroxene type structure. Unbranched zweier single chain {[BPO4F2]2?} represents a new type of borophosphate partial structure. zndabcoclrepresents the first organo-templated zincoborophosphate. The structure contains diaza-bicyclo[2.2.2]-octane (DABCO) which acts in its diprotonated form (H2DABCO)2+ as a pure template and in its monoprotonated form (HDABCO)+ as a ligand to Zn-positions at the borders of ribbons to complete structural motif. This compound is also the first example containing a quaternary Zn-tetrahedron (ZnO2NCl), and can formally be described as an adduct of (C6H14N2)Zn[ZnB2P4O15(OH)2] with diaza-bicyclo[2.2.2]octane-hydrochloride. The thermal behavior of zndabcocl has been studied by HT-XRD and DTA-TG in the temperature range 25?600 oC. The new phase occurring during the decomposition has been identified as HT-NH4[ZnBP2O8].DAP-Mnand PIP-Mn contain identical framework interconnections but difference in the shape of resulting channels, which are due to the different shape of organic templates. The crystal structures are built from the same building units: loop-branched single chains are connected via MnO6-octahedra resulting in a 3-D structure with intersecting channel systems running along [100], [011] and [01], respectively. The different shape of the template controls the shape of the channels, especially channels running along [100], resulting in dramatic shape-differences. The linear (H2DAP)2+ ions make the channels more elongated, while the cyclic (H2PIP)2+ ions give rise to more regular shaped channels. The flexibility of frameworks may be due to the more flexible coordination of Mn-atoms (octahedron and square pyramid).(C3H12N2){FeIII6(H2O)4[B4P8O32(OH)8]} is a new borophosphate with 3-D framework structure, a large size of 10-ring channel (778 ¡Ñ 867 pm2) is occupied by organic templates. The magnetic susceptibility measurements show it to exhibit antiferromagnetic susceptibility at low temperature (TN ?l 14K).dapvbpois the first mixed-valency vanadium borophosphate with a new structure type. Its structure can be considered as an ?intergrowth? of puckered vanadium(III) borophosphate layer (VIIIBPO-layer) and planar vanadium(IV) phosphate layers (VIVPO-layer) stacked and interconnected alternately along [001], which results in a new and unusual building motif. The corner sharing trimers of vanadium octahedra are observed for the first time in vanadium borophosphates. K3[B5PO10(OH)3] has a double unit cell of a twin crystal structure having the same chemical formula. The double b-axis solves the disorder problem of two oxygen positions coordinated to phosphorous. It represents a much more reasonable structure determination

    K2[FeII 3(P2O7)2(H2O)2]

    Get PDF
    The title compound, dipotassium diaqua­bis­(diphosphato)triferrate(II), K2[FeII 3(P2O7)2(H2O)2], was synthesized under solvothermal conditions. The crystal structure is isotypic with its Co analogue. In the structure, there are two crystallographically distinct Fe positions; one lies on an inversion center, the other on a general position. The first Fe2+ cation adopts a regular octa­hedral coordination with six O atoms, whereas the other is coordinated by five O atoms and a water mol­ecule. The [FeO6] octa­hedron shares its trans-edges with an adjacent [FeO5(H2O)] octahedron; in turn, the [FeO5(H2O)] octa­hedron shares skew-edges with a neighbouring [FeO6] octa­hedron and an [FeO5(H2O)] octa­hedron, resulting in a zigzag octa­hedral chain running along [001]. The zigzag chains are linked to each other by the P2O7 diphosphate groups, leading to a corrugated iron diphosphate layer, [Fe3(P2O7)2(H2O)2]2−, parallel to (100). The inter­layer space is occupied by K+ cations, which adopt an eight-coordination to seven O atoms and one water mol­ecule from a neighbouring iron diphosphate layer. Thus, the K+ ions not only compensate the negative charge of the layer but also link the layers into a network structure

    Higher-order Topological Phases of Magnons in van der Waals Honeycomb Ferromagnets

    Full text link
    We theoretically propose a second-order topological magnon insulator by stacking the van der Waals honeycomb ferromagnets with antiferromagnetic interlayer coupling. The system exhibits Z2_{2} topological phase, protected by pseudo-time-reversal symmetry (PTRS). An easy-plane anisotropy term breaks PTRS and destroys the topological phase. Nevertheless, it respects a magnetic two-fold rotational symmetry which protects a second-order topological phase with corner modes in bilayer and hinge modes along stacking direction. Moreover, an introduced staggered interlayer coupling establishes a Z2_{2}×\timesZ topology, giving rise to gapped topological surface modes carrying non-zero Chern numbers. Consequently, chiral hinge modes propagate along the horizontal hinges in a cuboid geometry and are robust against disorders. Our work bridges the higher-order topology and magnons in van der Waals platforms, and could be used for constructing topological magnonic devices

    Redetermination of Ce[B5O8(OH)(H2O)]NO3·2H2O

    Get PDF
    The crystal structure of Ce[B5O8(OH)(H2O)]NO3·2H2O, cerium(III) aqua­hydroxidoocta­oxidopenta­borate nitrate dihydrate, has been redetermined from single-crystal X-ray diffraction data. In contrast to the previous determination [Li et al. (2003 ▶). Chem. Mater. 15, 2253–2260], the present study reveals the location of all H atoms, slightly different fundamental building blocks (FBBs) of the polyborate anions, more reasonable displacement ellipsoids for all non-H atoms, as well as a model without disorder of the nitrate anion. The crystal structure is built from corrugated polyborate layers parallel to (010). These layers, consisting of [B5O8(OH)(H2O)]2− anions as FBBs, stack along [010] and are linked by Ce3+ ions, which exhibit a distorted CeO10 coordination sphere. The layers are additionally stabilized via O—H⋯O hydrogen bonds between water mol­ecules and nitrate anions, located at the inter­layer space. The [BO3(H2O)]-group shows a [3 + 1] coordination and is considerably distorted from a tetra­hedral configuration. Bond-valence-sum calculation shows that the valence sum of boron is only 2.63 valence units (v.u.) when the contribution of the water mol­ecule (0.49 v.u.) is neglected

    Coherence-protected Quantum Gate by Continuous Dynamical Decoupling in Diamond

    Full text link
    To implement reliable quantum information processing, quantum gates have to be protected together with the qubits from decoherence. Here we demonstrate experimentally on nitrogen-vacancy system that by using continuous wave dynamical decoupling method, not only the coherence time is prolonged by about 20 times, but also the quantum gates is protected for the duration of controlling time. This protocol shares the merits of retaining the superiority of prolonging the coherence time and at the same time easily combining with quantum logic tasks. It is expected to be useful in task where duration of quantum controlling exceeds far beyond the dephasing time.Comment: 5 pages, 4 figure

    Crystal structure of cobalt manganese monoaqua catena-[monohydrogenborate-tris(hydrogenphosphate)], (Co0.6Mn0.4)(2)(H2O) [BP3O9(OH)(4)]

    Get PDF
    BCo1.20H6Mn0.80O14P3, orthorhombic, P2(1)2(1)2(1) (no. 19), a = 7.1355(6) angstrom, b = 8.7321(8) angstrom, c = 16.405(2) angstrom, V = 1022.2 angstrom(3), Z = 4, R-gt(F) = 0.049, wR(ref)(F-2) = 0. 119, T = 295 K

    Lithium diaqua­magnesium catena-borodiphosphate(V) monohydrate, LiMg(H2O)2[BP2O8]·H2O, at 173 K

    Get PDF
    The crystal structure of LiMg(H2O)2[BP2O8]·H2O consists of tubular structural units, built from tetra­hedral ∞ 1{[BP2O8]3−} borophosphate ribbons and (LiO4)n helices running along [001], which are inter­connected by MgO4(H2O)2 octa­hedra, forming a three-dimensional network structure with one-dimensional channels along [001] in which the water mol­ecules are located. The water mol­ecule in the channel is significantly displaced by up to 0.3 Å from the special position 6b (..2) to a half-occupied general position. Mg, B and one Li atom all lie on twofold axes. Of the two Li positions, one is at a special position 6b (..2), while the other is at a general position; both are only half-occupied

    Tetra­aqua­tetra­manganese(II) catena-[germanodihydroxidodi(hydrogen­phosphate)diphosphate]

    Get PDF
    The title compound, Mn4(H2O)4[Ge(OH)2(HPO4)2(PO4)2], was synthesized by the solvothermal method. Its crystal structure is isotypic with the iron and cobalt analogues [Huang et al. (2012 ▶). Inorg. Chem. 51, 3316–3323]. In the crystal structure, the framework is built from undulating manganese phosphate sheets parallel to (010) inter­connected by GeO6 octa­hedra (at the inversion center), resulting in a three-dimensional network with eight-membered ring channels into which all the protons point. The undulating manganese phosphate sheet consists of zigzag manganese octa­hedral chains along [10-1], built from MnO4(OH)(OH2) octa­hedra and MnO5(OH2) octa­hedra by sharing their trans or skew edges, which are inter­connected by PO3(OH) and PO4 tetra­hedra via corner-sharing. The crystal structure features extensive O—H⋯O hydrogen-bonding inter­actions

    Cerium(III) dihydroxidohexa­oxidotetra­borate chloride

    Get PDF
    The crystal structure of the title compound, Ce[B4O6(OH)2]Cl, is built from polyborate sheets parallel to the (001) plane. These sheets stack along the [001] direction and are linked by Ce atoms exhibiting an CeO8Cl2 coordination sphere. O—H⋯O and O—H⋯Cl hydrogen bonds additionally stabilize the structural set-up. The polyborate sheet is made up of zigzag borate chains running along the [10] direction. These zigzag chains are inter­connected by shared O-vertices, resulting in a two-dimensional layer with nine-membered rings. All B and O atoms (except for the terminal OH atoms) lie in the nearly planar sheets of polyborates, leading to their isotropic atomic displacement parameters being significantly smaller than usual. This may be attributed to the fact that the atomic displacement parameters correlate not only with their atomic masses but with their coordination environments also

    Identification and determination of the major constituents in traditional Chinese medicine Longdan Xiegan Pill by HPLC-DAD-ESI-MS

    Get PDF
    AbstractA novel and sensitive HPLC-UV method has been developed for the simultaneous determination of twelve major compounds in Longdan Xiegan Pill. The chemical profile of the twelve compounds, including geniposidic acid (1), geniposide(2), gentiopicroside(3), liquiritin(4), crocin(5), baicalin(6), wogonoside(7), baicalein(8), glycyrrhizic acid (9), wogonin (10), oroxylin A (11) and aristolochic acid A (12), was acquired using high-performance liquid chromatography-diode array detector coupled with an electrospray tandem mass spectrometer (HPLC-DAD-ESI-MS). The analysis was performed on a Dikma Platisil ODS C18 column (250mm × 4. 6mm, 5μm) with a gradient solvent system of acetonitrile-0. 1% aqueous formic acid. The validation was carried out and the linearities (r>0. 9996), repeatability (RSD<1. 8%), intra- and inter-day precision (RSD< 1. 3%), and recoveries (ranging from 96. 6% to 103. 4%) were acceptable. The limits of detection (LOD) of these compounds ranged from 0.29 to 4. 17ng. Aristolochic acid A, which is the toxic ingredient, was not detected in all the batches of Longdan Xiegan Pill. Furthermore, hierarchical cluster analysis was used to evaluate the variation of the herbal prescription. The proposed method is simple, effective and suitable for the quality control of this traditional Chinese medicine (TCM)
    corecore