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1.
A new (β‐)modification of the mercury molybdate Hg2Mo2O7, thermodynamically stable at temperatures above 390 ± 10 °C, was prepared by solid state reaction of HgO with MoO2 in sealed silica tubes. Its crystal structure, determined from single‐crystal X‐ray data, has a very pronounced subcell: space group P2/c, a = 600.9(1) pm, b = 388.7(1) pm, c = 1428.4(2) pm, β = 105.88(1)°, Z = 2, R = 0.052 for 797 structure factors and 52 variable parameters. In the superstructure of this high‐temperature β‐modification the a and the b axes of the subcell are doubled: C2/c, a = 1201.9(2) pm, b = 777.3(1) pm, c = 1428.4(2) pm, β = 105.88(1)°, Z = 8, R = 0.040 for 1490 F values and 110 variables. Like the previously reported low‐temperature α‐modification, the β‐modification consists of two‐dimensionally infinite sheets of edge‐ and corner‐sharing MoO6 octahedra. These sheets are linked by Hg2 pairs. Thus, the structures of the two modifications (α and β) differ essentially only in the orientation of the Hg2 pairs, which are located between the sheets of the MoO6 octahedra. The superstructure of the β‐modification differs from the subcell‐structure by the puckering of the sheets of MoO6 octahedra. A hypothetical displacive phase transition between the subcell‐structure (corresponding to the potential high‐temperature structure) and the superstructure of β‐Hg2Mo2O7 is discussed. 相似文献
2.
A new zinc phosphite with the formula Zn3(tren)(HPO3)3·xH2O (x≈0.5) has been synthesized under hydrothermal conditions and characterized by FTIR, elemental analysis, powder X‐ray diffraction, single‐crystal X‐ray diffraction, thermogravimetric analysis and its fluorescent spectrum. The compound crystallizes in the triclinic system, space group (No.2), a = 10.1188(9) Å, b = 10.4194(9) Å, c = 10.5176(9) Å, α = 60.763(2)°, β = 70.6150(10)°, γ = 80.725(2)°, V = 912.77(14) Å3, Z = 2. The structure consists of double crankshaft chains, which are linked by Zn‐O‐P bonds to form 8‐ and 12‐membered channels along the [100] direction. The claw‐like Zn‐centered complexes of Zn(N4C6H18) as the supported templates, hang into the 12‐MR channels through Zn‐O‐P linkages with framework. 相似文献
3.
《Acta Crystallographica. Section C, Structural Chemistry》2018,74(8):917-922
Single crystals of the filled Ti2Ni‐type Ti3Zn3Ox η‐phase (cubic, space group Fdm) having {111} facets were obtained by heating Ti, Zn and ZnO with a Bi flux. The lattice parameter of a single crystal prepared at 800°C was 11.4990 (2) Å, which is close to that of Ti3Zn3O∼0.5 (a = 11.502 Å), as reported by Rogl & Nowotny [Monatsh. Chem. (1977), 108 , 1167–1180]. The occupancies of the O1 (16c) and O2 (8a) sites were 1 and 0.071 (12), respectively, and the composition of the crystal was determined to be Ti3Zn3O1.04. A single crystal from the sample prepared at 650°C had the same structure type, with a lattice parameter of 11.5286 (2) Å. However, O atoms were situated at a new 32e site in addition to the original 16c and 8a sites, and the Zn‐atom positions were split in accordance with the new O‐atom site. The chemical formula Ti3Zn3O1.27 determined by X‐ray diffraction occupancy refinement agreed with the chemical composition obtained for the cross section of the single crystal determined with an electron probe microanalyzer. 相似文献
4.
T. I. Krasnenko M. V. Rotermel’ S. A. Petrova R. G. Zakharov O. V. Sivtsova A. N. Chvanova 《Russian Journal of Inorganic Chemistry》2008,53(10):1641-1647
Phase relations in the Zn2V2O7-Cu2V2O7 system were studied by high-temperature X-ray diffraction and differential thermal analysis. The major phase constituents
of the system are solid solutions based on Zn2V2O7 and Cu2V2O7 polymorphs and their coexistence regions. The generation of α-Zn2 − 2x
Cu2x
V2O7 solid solution, where 0 ≤ x ≤ 0.30, leaves almost unchanged the stabilization temperature of the high-temperature zinc pyrovanadate phase. The α-Cu2 − 2x
Zn2x
V2O7 homogeneity range is 5 mol % Zn2V2O7. In the range 0.050 ≤ x ≤ 0.09 from 20 to ∼ 620°C, there is the two-phase field of α-Cu2V2O7 and β-Cu2V2O7 base solid solutions. At still higher temperatures, β-Zn2 − 2x
Cu2x
V2O7 and α-Cu2 − 2x
Zn2x
V2O7 coexist in the mixed-phase region. β-Zn2 − 2x
Cu2x
V2O7 solid solution, where 0 ≤ x ≤ 0.30, exists above 610 ± 5°C. The extent of the β′-Cu2V2O7-base solid solution is 9 to 65 mol % Zn2V2O7 at 615 ± 5°C, expanding to 0 mol % Zn2V2O7 with rising temperature.
Original Russian Text ¢ T.I. Krasnenko, M.V. Rotermel’, S.A. Petrova, R.G. Zakharov, O.V. Sivtsova, A.N. Chvanova, 2008, published
in Zhurnal Neorganicheskoi Khimii, 2008, Vol. 53, No. 10, pp. 1755–1762. 相似文献
5.
Thermodynamic Phase Transition Through Crystal‐to‐Crystal Process of Photochromic 1,2‐Bis(5‐phenyl‐2‐propyl‐3‐thienyl)perfluorocyclopentene
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A photochromic diarylethene, 1,2‐bis(5‐phenyl‐2‐propyl‐3‐thienyl)perfluorocyclopentene ( 1a ), was found to have two polymorphic crystal forms, α‐ and β‐crystals. From X‐ray crystallographic analysis, the space groups of α‐ and β‐crystals were determined to be P21/c and C2/c, respectively. The difference between two crystal forms is ascribed to the orientation of two of four molecules in the unit cell. The thermodynamic phase transition from α‐ to β‐forms occurred via a crystal‐to‐crystal process, as confirmed by differential scanning calorimetry measurements, optical microscopic observations in the reflection mode and under crossed Nicols, and powder X‐ray diffraction measurements. The movement of the molecules in the crystal was evaluated by analyzing the change of face indices before and after the phase transition. 相似文献
6.
A new metal‐oxo cluster supported transition metal complex, [Cu(en)2(H2O)]2[Cu(en)2]0.5[MoVI8VIV6VVO42{Cu(en)2}], has been synthesized under hydrothermal conditions. Its structure was determined by single‐crystal X‐ray diffraction. The compound crystallizes in the triclinic system, space group (No. 2), a = 12.245(5), b = 12.669(5), c = 20.949(8) Å, α = 77.120(13), β = 78.107(17), γ = 65.560(14)°, V = 2860(2) Å3, Z = 2. The metal‐oxo cluster contains a novel bicapped a‐Keggin structure unit and a [Cu(en)2]2+ unit covalently bonded to the [Mo8V7O42]7? cluster. 相似文献
7.
Meng Hu Dr. Sheng‐Chun Chen Zhi‐Hui Zhang Liang Wang Fu‐An Sun Ai‐Jun Cui Ming‐Yang He Prof. Qun Chen 《无机化学与普通化学杂志》2012,638(14):2329-2334
Three new coordination compounds, [Pb(HBDC‐I4)2(DMF)4]( 1 ) and [M(BDC‐I4)(MeOH)2(DMF)2]n (M = ZnII for 2 and MnII for ( 3 ) (H2BDC‐I4 = 2, 3, 5, 6‐tetraiodo‐1, 4‐benzenedicarboxylic acid), were synthesized and characterized by elemental analysis, IR spectroscopy, thermogravimetric (TG) analysis, and X‐ray single crystal structure analysis. Single‐crystal X‐ray diffraction reveals that 1 crystallizes in the monoclinic space group C2/c and has a discrete mononuclear structure, which is further assembled to form a two‐dimensional (2D) layer through intermolecular O–H ··· O and C–H ··· O hydrogen bonding interactions. The isostructural compounds 2 and 3 crystallize in the space group P21/c and have similar one‐dimensional (1D) chain structures that are extended into three‐dimensional (3D) supramolecular networks by interchain C–H ··· π interactions. The PbII and ZnII complexes 1 and 2 display similar emissions at 472 nm in the solid state, which essentially are intraligand transitions. 相似文献
8.
Two complexes, cis‐[MnL2(NCS)2] ( 1 ) and cis‐[ZnL2(NCS)2] ( 2 ) with asymmetrical substituted triazole ligands [L = 3,4‐dimethyl‐5‐(2‐pyridyl)‐1,2,4‐triazole], were synthesized and characterized by elemental analysis, UV/Vis and FT‐IR spectroscopy as well as thermogravimetric analyses (TGA), powder XRD, and single‐crystal X‐ray diffraction. In the complexes, each L molecule adopts a chelating bidentate mode by the nitrogen atoms of pyridyl and triazole. Both complexes have a similar distorted octahedral [MN6] core (M = Mn2+ and Zn2+) with two NCS– ions in the cis position. 相似文献
9.
Emily J. Hopkins Dr. Yurii Prots Dr. Ulrich Burkhardt Dr. Yves Watier Dr. Zhiwei Hu Dr. Chang‐Yang Kuo Dr. Jen‐Che Chiang Dr. Tun‐Wen Pi Dr. Arata Tanaka Prof. Liu Hao Tjeng Dr. Martin Valldor 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(21):7938-7943
Through a solid‐state reaction, a practically phase pure powder of Ba3V2S4O3 was obtained. The crystal structure was confirmed by X‐ray single‐crystal and synchrotron X‐ray powder diffraction (P63, a=10.1620(2), c=5.93212(1) Å). X‐ray absorption spectroscopy, in conjunction with multiplet calculations, clearly describes the vanadium in charge‐disproportionated VIIIS6 and VVSO3 coordinations. The compound is shown to be a strongly correlated Mott insulator, which contradicts previous predictions. Magnetic and specific heat measurements suggest dominant antiferromagnetic spin interactions concomitant with a weak residual ferromagnetic component, and that intrinsic geometric frustration prevents long‐range order from evolving. 相似文献
10.
Erick‐Adrian Juarez‐Arellano Ivonne Rosales Lauro Bucio Eligio Orozco 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(10):i135-i137
Indium gadolinium digermanium heptaoxide, In1.08Gd0.92Ge2O7, with a thortveitite‐type structure, has been prepared as a polycrystalline powder material by a high‐temperature solid‐state reaction. As in the mineral thortveitite, the crystal structure belongs to the monoclinic system, with space group C2/m (No. 12). The precise structural parameters were obtained by applying the Rietveld method of refinement to the X‐ray powder diffraction data. This layered structure presents, on one side, a honeycomb‐like arrangement of the unique octahedral site, which is occupied randomly by In and Gd atoms, and, on the other side, sheets of isolated Ge2O7 diortho‐groups made up of double tetrahedra sharing a common vertex and displaying C2h point symmetry. This compound showed a remarkable photoluminescence effect when it was irradiated with the X‐ray beam during the X‐ray diffraction measurements, and with the α beam during the Rutherford back‐scattering spectrometry experiments employed to analyze the chemical stoichiometry. 相似文献
11.
Bertold Rasche Minjun Yang Lothar Nikonow Joshaniel F. K. Cooper Claire A. Murray Sarah J. Day Karin Kleiner Simon J. Clarke Richard G. Compton 《Angewandte Chemie (International ed. in English)》2019,58(43):15401-15406
We report the precise postsynthetic control of the composition of β‐Fe1+xSe by electrochemistry with simultaneous tracking of the associated structural changes via in situ synchrotron X‐ray diffraction. We access the full phase width of 0.01<x<0.04 and identify the superconducting state below 8 K, which in contrast to earlier reports is independent of the composition. However, in a second set of in situ X‐ray diffraction experiments, we demonstrate that β‐Fe1+xSe forms a new phase in the presence of oxygen above a 100 °C which has the same anti‐PbO type structure but is not superconducting down to 1.8 K. The latter process can be reversed electrochemically to reinstate the superconducting state. These observations exploit the exquisite control afforded by electrochemistry in contrast with classical approaches of chemical synthesis. 相似文献
12.
James Hoos Nian‐Tzu Suen Svilen Bobev 《Acta Crystallographica. Section C, Structural Chemistry》2014,70(10):945-948
The focus of this paper is on the synthesis and crystal structures of three Zn‐rich compounds with the general formula RE7Zn21+xSi2−x, where RE = Ce [x = 0.95 (1); heptacerium docosazinc silicon], Pr [x = 0.09 (1); heptapraseodymium henicosazinc disilicon], and Nd [x = 0.53 (1); heptaneodymium docosazinc silicon]. The compounds were obtained by high‐temperature reactions, using the respective elements as starting materials. The structures were determined by single‐crystal X‐ray diffraction. The title compounds crystalize in the orthorhombic space group Pbam (No. 55, Pearson symbol oP60) and are isostructural with about a dozen RE7Zn21+xTt2−x (RE = La–Nd; Tt = Ge, Sn, and Pb) compounds previously reported by our group. The results from the present refinements confirm the previously published data on RE7Zn21+xSi2−x (RE = La and Ce; x≃ 1.45) [Malik et al. (2013). Intermetallics, 36 , 118–126]. Additionally, magnetic susceptibility measurements on the corresponding bulk samples show Curie–Weiss paramagnetic behavior from 5 to 300 K, consistent with RE3+ ground states and local‐moment magnetism due to the core 4f electrons. 相似文献
13.
Ali Hejrani‐Dalir Masumeh Tabatabaee Ali Sheibani 《Acta Crystallographica. Section C, Structural Chemistry》2015,71(2):89-92
2‐Amino‐3‐hydroxypyridinium dioxido(pyridine‐2,6‐dicarboxylato‐κ3O2,N,O6)vanadate(V), (C5H7N2O)[V(C7H3NO4)O2] or [H(amino‐3‐OH‐py)][VO2(dipic)], (I), was prepared by the reaction of VCl3 with dipicolinic acid (dipicH2) and 2‐amino‐3‐hydroxypyridine (amino‐3‐OH‐py) in water. The compound was characterized by elemental analysis, IR spectroscopy and X‐ray structure analysis, and consists of an anionic [VO2(dipic)]− complex and an H(amino‐3‐OH‐py)+ counter‐cation. The VV ion is five‐coordinated by one O,N,O′‐tridentate dipic dianionic ligand and by two oxide ligands. Thermal decomposition of (I) in the presence of polyethylene glycol led to the formation of nanoparticles of V2O5. Powder X‐ray diffraction (PXRD) and scanning electron microscopy (SEM) were used to characterize the structure and morphology of the synthesized powder. 相似文献
14.
Alexandra Lieb Juliane A. Kechele Robert Kraut Wolfgang Schnick Prof. Dr. 《无机化学与普通化学杂志》2007,633(1):166-171
The oxonitridoalumosilicates (so‐called sialons) MLn[Si4?xAlxOxN7?x] with M = Eu, Sr, Ba and Ln =Ho, Er, Tm, Yb were obtained by the reaction of the respective lanthanoid metal, the alkaline earth carbonates or europium carbonate, resp., AlN, “Si(NH)2” and MCl2 as a flux in a radiofrequency furnace at temperatures around 2100 °C. The compounds MLn[Si4?xAlxOxN7?x] are relevant for the investigation of substitutional effects on the materials properties due to their ability of tolerating a comparatively large phase width up to x ≈ 2.0(5). The crystal structures of the twelve compounds were refined from X‐ray single crystal data and X‐ray powder data and are found to be isotypic to the MYb[Si4N7] structure type. The compounds crystallize in space group P63mc (no. 186, hexagonal) and are made up of chains of so‐called starlike units [N[4](SiN3)4] or [N[4]((Si,Al)(O,N)3)4], respectively. These units are formed by four (Si,Al)(N/O)4 tetrahedra sharing a common central nitrogen atom. The structure refinement was performed utilizing an O/N‐distribution model according to Paulings rules, i.e. nitrogen was positioned on the four‐fold bridging site and nitrogen and oxygen were distributed equally on both of the two‐fold bridging sites, resulting in charge neutrality of the compound. The Si and Al atoms were distributed equally on their two crystallographic sites, referring to their elemental proportion in the compound, due to being poorly distinguishable by X‐ray methods. The chemical compositions of the compounds were derived from electron probe micro analyses (EPMA). 相似文献
15.
Michael Wrle Frank Krumeich Fabian Bieri Hans‐Joachim Muhr Reinhard Nesper 《无机化学与普通化学杂志》2002,628(12):2778-2784
The walls of vanadium oxide nanotubes (VOx‐NTs) are built up by vanadate layers between which the structure‐directing template, either a primary amine or a diamine with long alkyl chain, is located. The feasibility of various exchange reactions under preservation of the tubular morphology indicates a high structural flexibility of the VOx‐NTs. The structure of the vanadate layers appears to be the same in all tubular vanadates, as revealed by the similarity of the diffraction patterns. Plate‐like crystals of a new crystalline phase, structurally closely related to the nanotubes, have now been prepared with ethylene diamine, applying a route that is analogous to the VOx‐NT synthesis. The single crystal X‐ray structure determination showed that this new phase has the composition (en)V7O16 and crystallizes with triclinic symmetry. The structure is composed of V7O16 layers between which ethylene diamine mo le cules are embedded. The V7O16 layers comprise two sheets of square VO5 pyramids and VO4 tetrahedra that connect these sheets. The available experimental data establish that this V7O16 layer also is the basic element of the VOx‐NT wall structure. The simulated X‐ray powder diffraction pattern calculated with a corresponding structural mode for VOx‐NTs agrees well with the observed one. 相似文献
16.
Visualization of the Heterogeneity of Cerium Oxidation States in Single Pt/Ce2Zr2Ox Catalyst Particles by Nano‐XAFS
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Dr. Nozomu Ishiguro Prof. Dr. Tomoya Uruga Dr. Oki Sekizawa Dr. Takuya Tsuji Dr. Motohiro Suzuki Dr. Naomi Kawamura Dr. Masaichiro Mizumaki Dr. Kiyofumi Nitta Prof. Dr. Toshihiko Yokoyama Prof. Dr. Mizuki Tada 《Chemphyschem》2014,15(8):1563-1568
The cerium oxidation states in single catalyst particles of Pt/Ce2Zr2Ox (x=7 to 8) were investigated by spatially resolved nano X‐ray absorption fine structure (nano‐XAFS) using an X‐ray nanobeam. Differences in the distribution of the Ce oxidation states between Pt/Ce2Zr2Ox single particles of different oxygen compositions x were visualized in the obtained two‐dimensional X‐ray fluorescent (XRF) mapping images and the Ce LIII‐edge nano X‐ray absorption near‐edge structure (nano‐XANES) spectra. 相似文献
17.
Erick A. Juarez‐Arellano Ivonne Rosales Alicia Oliver Jose Luis Ruvalcaba Raul E. Carbonio Lauro Bucio Eligio Orozco 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(2):i14-i16
A new indium holmium digermanate, In1.06Ho0.94Ge2O7, with a thortveitite‐type structure, has been prepared as a polycrystalline powder material by high‐temperature solid‐state reaction. This new compound crystallizes in the monoclinic system (space group C2/c, No. 15). The structure was characterized by Rietveld refinement of powder laboratory X‐ray diffraction data. The In3+ and Ho3+ cations occupy the same octahedral site, forming a hexagonal arrangement on the ab plane. In their turn, the hexagonal arrangements of (In/Ho)O6 octahedral layers are held together by sheets of isolated diortho groups comprised of double tetrahedra sharing a common vertex. In this compound, the Ge2O7 diortho groups lose the ideal D3d point symmetry and also the C2h point symmetry present in the thortveitite diortho groups. The Ge—O—Ge angle bridging the diortho groups is 160.2 (3)°, compared with 180.0° for Si—O—Si in thortveitite (Sc2Si2O7). The characteristic mirror plane in the thortveitite space group (C2/m, No. 12) is not present in this new thortveitite‐type compound and the diortho groups lose the C2h point symmetry, reducing to C2. 相似文献
18.
Crystal Chemistry of the M11+,2+–M22+,3+–(H)‐Arsenites: the First Cadmium(II) Arsenite,Na4Cd7(AsO3)6
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Tamara Đorđević 《无机化学与普通化学杂志》2015,641(11):1863-1868
The crystal structures among M1–M2–(H)‐arsenites (M1 = Li+, Na+, K+, Rb+, Cs+, Ca2+, Sr2+, Ba2+, Cd2+, Pb2+; M2 = Mg2+, Mn2+,3+, Fe2+,3+, Co2+, Ni2+, Cu2+, Zn2+) are less investigated. Up to now, only the structure of Pb3Mn(AsO3)2(AsO2OH) was described. The crystal structure of hydrothermally synthesized Na4Cd7(AsO3)6 was solved from the single‐crystal X‐ray diffraction data. Its trigonal crystal structure [space group R$\bar{3}$ , a = 9.5229(13), c = 19.258(4) Å, γ = 120°, V = 1512.5(5) Å3, Z = 3] represents a new structure type. The As atoms are arranged in monomeric (AsO3)3– units. The surroundings of the two crystallographically unique sodium atoms show trigonal antiprismatic coordination, and two mixed Cd/Na sites are remarkably unequal showing tetrahedral and octahedral coordinations. Despite the 3D connection of the AsO3 pyramids, (Cd,Na)Ox polyhedra and NaO6 antiprisms, a layer‐like arrangement of the Na atoms positioned in the hexagonal channels formed by CdO4 deformed tetrahedra and AsO3 pyramids in z = 0, 1/3, 2/3 is to be mentioned. These pseudo layers are interconnected to the 3D network by (Cd,Na)O6 octahedra. Raman spectra confirmed the presence of isolated AsO3 pyramids. 相似文献
19.
Nobuo Ishizawa Reiko Yamashita Shuji Oishi James R. Hester Shunji Kishimoto 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(9):1006-1009
The triclinic superstructure of a small crystal of LiCa2Nb3O10, lithium dicalcium triniobium decaoxide, has been investigated by synchrotron X‐ray diffraction. The unit cell is an almost rectangular parallelepiped, although there is a 0.245° offset from orthogonality for β. The structure essentially belongs to a homologous series of Li[Nan?3Ca2NbnO3n+1] with n = 3, where the moiety in square brackets has a perovskite‐type slab structure. The superstructure has a doubled unit‐cell volume with respect to the tetragonal aristotype. The NbO6 octahedra are rotated about axes parallel to [110] by approximately 10°. Adjacent slabs are connected by Li atoms and are geometrically related by 42 pseudosymmetry lying parallel to c . There are twice as many sites as Li atoms, providing a variation of population at these Li sites. 相似文献
20.
Despite a significant advancement in preparing metastable materials, one common problem is the strict and precious reaction conditions due to their metastable structures. Herein, we achieved the preparation of high‐temperature stabilized metastable α‐MoC1?x by mounting zinc atoms into its lattice structure. Such a structural construction could suppress the phase transformation from α‐MoC1?x to β‐Mo2C through restricting the displacement of Mo atoms upon increased temperature. The resultant metastable α‐MoC1?x can be stabilized up to 1000 °C and this stability temperature is the highest for the metastable α‐MoC1?x so far. Synchrotron X‐ray absorption spectroscopy (XAS) and X‐ray photoelectron spectroscopy (XPS) confirm the structure of Zn‐mounted α‐MoC1?x. Density functional theory (DFT) calculations reveal that the introduction of the Zn atoms in the lattice structure of α‐MoC1?x could significantly decrease the energy difference (ΔE) between α‐MoC1?x and β‐Mo2C, thus effectively suppressing the phase transformation from α‐MoC1?x to β‐Mo2C and accordingly maintaining the high‐temperature stability of α‐MoC1?x. This novel strategy can be used as a universal method to be extended to synthesize metastable α‐MoC1?x from different precursors or other mounted elements. Moreover, the optimal product exhibits excellent lithium storage performances in terms of the cycling stability and rate performance. 相似文献