In situ synchrotron radiation investigation of V2O5–Nb2O5 metastable compounds: transformational kinetics at high temperatures with a new structural solution for the orthorhombic V4Nb20O60 phase

2020 ◽  
Vol 49 (48) ◽  
pp. 17584-17593
Author(s):  
Laura Caggiu ◽  
Antonio Iacomini ◽  
Claudio Pistidda ◽  
Valeria Farina ◽  
Nina Senes ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Synchrotron Radiation ◽  
High Temperatures ◽  
Lattice Parameters ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
Metastable Compounds ◽  
Xrd Patterns ◽  
Structural Solution

In situ synchrotron and conventional XRD patterns were solved for the phase developed at 700 °C with the Amm2 orthorhombic space group, lattice parameters a = 21.187 Å; b = 3.827 Å; c = 19.377 Å; β = 119.83° and chemical composition V4Nb20O60 (ρ = 4.09 g cm−3).

About the air- and water-stable copper(I) dicyanamide: synthesis, crystal structure, vibrational spectra and DSC/TG analysis of Cu[N(CN)2]

2017 ◽  
Vol 72 (2) ◽  
pp. 159-165 ◽  
Author(s):  
Olaf Reckeweg ◽  
Robert E. Dinnebier ◽  
Armin Schulz ◽  
Björn Blaschkowski ◽  
Christof Schneck ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Vibrational Spectra ◽  
Lattice Parameters ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
Tg Analysis ◽  
Space Group ◽  
X Ray ◽  
Light Yellow

AbstractLight-yellow microcrystalline samples of Cu[dca] ([dca]−≡[N(CN)2]−≡dicyanamide anion) were obtained by blending an in-situ generated aqueous Cu+ brine with stoichiometric amounts of Na[dca] dissolved in water. The crystal structure of Cu[dca] was solved and refined from powder X-ray diffraction (PXRD) data. Cu[dca] crystallizes in the orthorhombic space group Cmcm (no. 63) with the lattice parameters of a=356.28(3), b=611.10(9) and c=1525.87(10) pm. The crystal structure contains undulated chains of alternating Cu+ and boomerang-shaped [N≡C–N–C≡N]− ions with C2v symmetry running along [100]. It is closely related to that of Ag[dca] crystallizing in space group Pnma (no. 62). The vibrational spectra for Cu[dca] and Cu[dca]2 were recorded exhibiting modes typical for the dicyanamide anion. Comparative DSC/TG measurements were performed for both copper dicyanamides and the cyanide Cu[CN].

scholarly journals β-Y(BO2)3 – a new member of the β-Ln(BO2)3 (Ln=Nd, Sm, Gd–Lu) structure family

2017 ◽  
Vol 72 (12) ◽  
pp. 983-988 ◽  
Author(s):  
Martin K. Schmitt ◽  
Hubert Huppertz
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Lattice Parameters ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
X Ray

Abstractβ-Y(BO2)3 was synthesized in a Walker-type multianvil module at 5.9 GPa/1000°C. The crystal structure has been elucidated through single-crystal X-ray diffraction. β-Y(BO2)3 crystallizes in the orthorhombic space group Pnma (no. 62) with the lattice parameters a=15.886(2), b=7.3860(6), and c=12.2119(9) Å. Its crystal structure will be discussed in the context of the isotypic lanthanide borates β-Ln(BO2)3 (Ln=Nd, Sm, Gd–Lu).

Synthese eines kubanartigen Clusterchelats mit einem [Mo3SnS4]6+-Kern / Synthesis of a Cubane-Type Cluster Chelate with a [Mo3SnS4]6+ Core

1990 ◽  
Vol 45 (4) ◽  
pp. 461-464 ◽  
Author(s):  
Helmut Keck ◽  
Andreas Kruse ◽  
Wilhelm Kuchen ◽  
Dietrich Mootz ◽  
René Wiskemann ◽  
...  
Keyword(s):  
Lattice Parameters ◽  
The Other ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
The Core

The cubane-type diamagnetic cluster Mo3SnS4(Et2PS2)6 (1) is obtained by reaction of the “incomplete” cubane Mo3S4(Et2PS2)4 either with tin powder and Et2P(S)—S—S—P(S)Et2 or with bis(diethyldithiophosphinato)tin(II). While the Sn atom and two of the Mo atoms in the core are chelated by Et2PS2⁻, the remaining Mo atom serves as a bridgehead for three dithiophosphinato-ligand bridges to the other metals. 1 crystallizes in the orthorhombic space group Pbca with Z = 8 and lattice parameters a = 2240( 1), b = 2261 ( 1), c = 2401 (1) pm.

Structure–melting relations in isomeric dibromobenzenes

2014 ◽  
Vol 70 (3) ◽  
pp. 492-497 ◽  
Author(s):  
Kamil F. Dziubek ◽  
Andrzej Katrusiak
Keyword(s):  
Melting Point ◽  
Ambient Pressure ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Glass Capillary ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
Diamond Anvil ◽  
Higher Temperature

1,4-Dibromobenzene melts at a considerably higher temperature than the 1,2- and 1,3-isomers. This melting-point difference is consistent with the molecular symmetry, as described by Carnelley's rule, and with the frequency of Br...Br halogen bonds. The lowest melting point of 1,3-dibromobenzene correlates with its two symmetry-independent molecules, indicating their inability to pack closely. Single crystals of 1,2- and 1,3-dibromobenzene have been grown under isochoric conditions in a diamond–anvil cell and at isobaric conditions in a glass capillary. Their structures have been determinedin situby X-ray diffraction. At 295 K 1,2-dibromobenzene crystallizes at 0.2 GPa as orthorhombic, space groupPbca,Z′ = 1, and 1,3-dibromobenzene at 0.3 GPa as orthorhombic, space groupP212121,Z′ = 2. The same crystal phases are formed at ambient pressure by freezing these liquids below 256.15 and 248.45 K, respectively. The third isomer, 1,4-dibromobenzene, is a solid at room temperature and crystallizes as monoclinic, space groupP21/a. Striking relations between the structures and melting points of the corresponding dibromobenzene and dichlorobenzene isomers have been discussed.

Crystal Structure of the New Compound NdFeSb3

2007 ◽  
Vol 353-358 ◽  
pp. 3043-3046 ◽  
Author(s):  
Ping Li Qin ◽  
Liang Qin Nong ◽  
Ji Liang Zhang ◽  
Hai Qing Qin ◽  
Jiang Ping Liao ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Rietveld Method ◽  
Structure Type ◽  
Lattice Parameters ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
X Ray

The crystal structure of a new compound NdFeSb3 has been determined by X-ray powder diffraction using the Rietveld method. The compound crystallizes in the orthorhombic, space group Pbcm (No.57) with the CeNiSb3 structure type and lattice parameters a=1.26828(2)nm, b=0.61666(2)nm, c=1.81867(4) nm, z=12 and Dcalc=7.917g/cm3.

Modulated structures of Cs2HgCl4: the 5a superstructure at 185 K and the 3c superstructure at 176 K

1999 ◽  
Vol 55 (6) ◽  
pp. 886-895 ◽  
Author(s):  
Bagautdin Bagautdinov ◽  
Katrin Pilz ◽  
Jens Ludecke ◽  
Sander van Smaalen
Keyword(s):  
Synchrotron Radiation ◽  
Room Temperature ◽  
Normal Phase ◽  
Lattice Parameters ◽  
Temperature Structure ◽  
Space Group ◽  
X Ray ◽  
X Ray Scattering ◽  
Modulated Structures ◽  
Modulated Phase

Crystalline dicaesium mercury tetrachloride (Cs2HgCl4) is isomorphous with \beta-K_2SO_4 (space group Pnma, Z = 4) in its normal phase at room temperature. On cooling a sequence of incommensurate and commensurate superstructures occurs, below T = 221 K with modulations parallel to a*, and below 184  K with modulations along c*. The commensurately modulated structures at T = 185 K with {\bf q}= {{1}\over{5}}\bf{a}^* and at T = 176 K with {\bf q} = {{1}\over{3}}\bf{c}^* were determined using X-ray scattering with synchrotron radiation. The structure at T = 185 K has superspace group Pnma(\alpha,0,0)0ss with \alpha = 0.2. Lattice parameters were determined as a = 5\times9.7729\kern2pt(1), b = 7.5276\kern2pt(4) and c = 13.3727\kern2pt(7) Å. Structure refinements converged to R = 0.050 (R = 0.042 for 939 main reflections and R = 0.220 for 307 satellites) for the section t = 0.05 of superspace. The fivefold supercell has space group Pn2_1a. The structure at T = 176 K has superspace group Pnma(0,0,\gamma)0s0 with \gamma = {{1}\over{3}}. Lattice parameters were determined as a = 9.789\kern2pt(3), b = 7.541 \kern2pt(3) and c = 3 \times 13.418\kern2pt(4) Å. Structure refinements converged to R = 0.067 (R = 0.048 for 2130 main reflections, and R = 0.135 for 2382 satellite reflections) for the section t = 0. The threefold supercell has space group P112_1/a. It is shown that the structures of both low-temperature phases can be characterized as different superstructures of the periodic room-temperature structure. The superstructure of the 5a-modulated phase is analysed in terms of displacements of the Cs atoms, and rotations and distortions of HgCl4 tetrahedral groups. In the 3c-modulated phase the distortions of the tetrahedra are relaxed, but they are replaced by translations of the tetrahedral groups in addition to rotations.

scholarly journals Clusterdithiophosphinate mit kubanartigem Mo2M2S4-Kern (M = Co, W) / Clusterdithiophosphinates with Cubane-Type Mo2M2S4-Core (M = Co, W)

1993 ◽  
Vol 48 (5) ◽  
pp. 548-554 ◽  
Author(s):  
Hansjörg Diller ◽  
Helmut Keck ◽  
Andreas Kruse ◽  
Wilhelm Kuchen
Keyword(s):  
Spectroscopic Data ◽  
Mixed Crystal ◽  
Lattice Parameters ◽  
Chelating Ligands ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
Bridging Ligand ◽  
Tetranuclear Complexes

The syntheses of tetranuclear complexes Mo,W2S4L6 3 and Mo2Co2S4L2(CO)2(CH3CN)2 4 (L = R2PS2⁻; a: R = Et, b: R = Pr) containing the cubane-type Mo2M2S4 core are reported. While in 4 both Mo atoms are chelated by L, the dithiophosphinato group acts as a chelating and bridging ligand in 3. It is shown that there exist four isomers of 3 which differ not only in the function of L but also in the kind of metals which are chelated and bridged. Magnetic and NMR spectroscopic data are given. The structure of a mixed crystal of the two β-isomers of 3a containing three bridging and three chelating ligands L is reported: orthorhombic space group Pbca, Z = 8, and lattice parameters a = 2186.6(7), b = 2264.0(7), and c = 2386.7(6) pm.

Syntheses and Crystal Structures of the Two New Polychalcogenides [Mn(C6H14N2)3]Se6 and [Mn(C6H14N2)3]2[C6H16N2](TeSe2)2Se

2004 ◽  
Vol 59 (6) ◽  
pp. 629-634 ◽  
Author(s):  
Frank Wendland ◽  
Christian Näther ◽  
Wolfgang Bensch
Keyword(s):  
Hydrogen Bonding ◽  
Single Step ◽  
Lattice Parameters ◽  
Solvothermal Reaction ◽  
Monoclinic Space Group ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
Layer Arrangement ◽  
Weak Hydrogen Bonding ◽  
Dark Blue

The solvothermal reaction of MnCl2·4 H2O, K2Se3 and Se in trans-cyclohexane-1,2-diamine (chxn) at 433 K yields dark blue crystals of [Mn(chxn)3]Se6 (1), and the reaction of MnCl2 ・4 H2O, K2Se3 and Te under similar conditions gives dark blue crystals of [Mn(chxn)3]2[H2chxn](TeSe2)2Se (2). While compound (1) crystallises in the orthorhombic space group Pbcn with the lattice parameters a = 13.7017(9), b = 19.9073(8) and c = 10.8058(5)Å , compound (2) crystallises in the monoclinic space group P21 with the lattice parameters a = 9.4396(6), b = 24.2450(2), c = 12.8170(8) Å and β =91.6(1)◦. In both structures discrete complex cations and polychalcogenide anions are found. In (1) the Se62− anions form a pseudo-layer arrangement with nearly rectangular pores. The complex cations are encapsulated by the arrangement of the Se62− anions. Some short distances between the amino groups of the ligands and the anions indicate weak hydrogen bonding. In compound (2) two independent [Mn(chxn)3]2+ and one unique H2chxn dications, two unique TeSe22− as well as one Se2− dianion coexist. The two complex cations exhibit different conformations. One of the two TeSe22− anions has the di-protonated chxn molecule in the neighbourhood and short Se···H separations indicate weak hydrogen bonding. The isolated Se2− ion is located above the ring of the di-protonated trans-cyclohexane-1,2-diamine molecule and again a short Se···H separation may be due to a weak hydrogen bond. Compound (1) decomposes in a single step when heated in an Ar atmosphere. In contrast, the thermal decomposition of compound (2) is complex and at least five different steps can be identified.

Strukturen und Schwingungsspektren des Tetramethylammonium -a -dodekawolframatosilikats und des Tetrabutylammonium-β-dodekawolframatosilikats / Structures and Vibrational Spectra of Tetramethylammonium a-Dodecatungstosilicate and Tetrabutylammonium β-Dodecatungstosilicate

1981 ◽  
Vol 36 (2) ◽  
pp. 161-171 ◽  
Author(s):  
Joachim Fuchs ◽  
Axel Thiele ◽  
Rosemarie Palm
Keyword(s):  
Crystal Structure ◽  
Vibrational Spectra ◽  
Lattice Parameters ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
Crystal Water ◽  
Space Group ◽  
X Ray ◽  
First Time

Abstract Dodecatungstosilicates free of crystal water were prepared for the first time by using tetraalkylammonium as cation. The crystal structure of the tetramethylammonium a-dodeeatungstosilicate [N(CH3)4]4SiW12O40 (1) and tetrabutylammonium) β-dodecatungstosilicate, [N(C4H9)4]4SiWi2040 (2) were solved by X-ray diffraction. (1) crystallizes tetragonal in the space group 14̅ with lattice parameters a = 14.642 Å; c= 12.706 Å; (2) orthorhombic, space group P212121 with a = 29.277 Å, b = 22.181 Å and c = 15.381 Å. The differences between the two isomeric heteropolyanions are discussed, especially the distances and angles between the tungsten atoms. Comparison of characteristic differences in the vibrational spectra permits the identification of the isomeric anions.

Compression of the perovskite-related mineral bernalite Fe(OH)3 to 9 GPa and a reappraisal of its structure

2005 ◽  
Vol 69 (3) ◽  
pp. 309-315 ◽  
Author(s):  
M. D. Welch ◽  
W. A. Crichton ◽  
N. L. Ross
Keyword(s):  
Elastic Moduli ◽  
Second Order ◽  
Lattice Parameters ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
X Ray ◽  
The Difference ◽  
Murnaghan Equation ◽  
Tetragonal Cell ◽  
Rare Opportunity

AbstractThe octahedral-framework mineral bernalite, Fe(OH)3, provides a rare opportunity to examine directly the effects of a vacant A site upon the physical properties of perovskite-like structures. Here, we report the effect upon compressibility. Bernalite has been reported previously as having space group Immm (Birch et al., 1993), but numerous reflections violating I-centering were observed in the present study. A case is presented for bernalite having orthorhombic space group Pmmn. Lattice parameters were refined using the Le Bail method for a metrically tetragonal cell and their variation with pressure at room temperature was determined from 17 measurements at pressures from 10–4 to 9.3 GPa using synchrotron X-ray powder diffraction. No discontinuities in the compression curves of lattice parameters were observed. Fitting to a second-order Birch-Murnaghan equation-of-state (KT0' = 4) gives V0 = 438.51±0.06 Å3 and KT0 = 78.2±0.4 GPa. Second-order fits of (a/a0)3 and (c/c0)3 give elastic moduli KT0a = 82.0(6) GPa and KT0c = 71.6(4) GPa: the shorter cation–cation distance is the more compressible. These values are very close to those of stottite, FeGe(OH)6, which has tilt system a+a+c–. The difference in the elastic moduli KT0a and KT0c of bernalite and their close similarity to the stottite values support the revised Pmmn structure (tilt system a+b+c–) for bernalite proposed here. The compressional anisotropy observed in bernalite may reflect its highly anisotropic and directional H-bonding topology.

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