The crystal chemistry of rhodizite: a re-examination

1986 ◽  
Vol 50 (355) ◽  
pp. 163-172 ◽  
Author(s):  
A. Pring ◽  
V. K. Din ◽  
D. A. Jefferson ◽  
J. M. Thomas
Keyword(s):  
Single Crystal ◽  
Crystal Chemistry ◽  
Structure Refinement ◽  
High Resolution Electron Microscopy ◽  
Basic Structure ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Alkali Cations ◽  
X Ray ◽  
Using Data

AbstractThe crystal chemistry of rhodizite was re-examined using data from high-resolution electron microscopy (HREM), magic angle spinning nuclear magnetic resonance (MASNMR), a single crystal X-ray structure refinement, and a new chemical analysis. The analysis calculates to the formula: (K0.46Cs0.36Rb0.06 Na0.02)Σ0.90Al3.99Be4(B11·35Be0.55Li0.02)O28· The distribution of alkali cations was shown to be truly random by HREM images and computer image simulations. The distribution of boron and beryllium was monitored by MASNMR, the spectra for both elements gave only single resonances indicating that all beryllium and boron atoms are located in chemically equivalent sites. The structure of rhodizite was refined by single crystal X-ray diffraction techniques. The mineral is cubic a = 7.318(1) Å, space group P3. A full matrix least-squares refinement using 152 unique observed reflections [F > 3σ(F)] converged to R = 0.0344. The refinement confirmed the basic structure as determined by Taxer and Buerger (1967), 4 beryllium atoms of the unit cell were found to occupy a 4e special position, the remaining 0.5 being randomly distributed with the 11.35 boron atoms over the 12h sites.

scholarly journals High-temperature in situ crystallographic observation of reversible gas sorption in impermeable organic cages

2015 ◽  
Vol 112 (46) ◽  
pp. 14156-14161 ◽  
Author(s):  
Seung Bin Baek ◽  
Dohyun Moon ◽  
Robert Graf ◽  
Woo Jong Cho ◽  
Sung Woo Park ◽  
...  
Keyword(s):  
Single Crystal ◽  
High Temperatures ◽  
Direct Detection ◽  
Variable Temperature ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dynamic Motion

Crystallographic observation of adsorbed gas molecules is a highly difficult task due to their rapid motion. Here, we report the in situ single-crystal and synchrotron powder X-ray observations of reversible CO2 sorption processes in an apparently nonporous organic crystal under varying pressures at high temperatures. The host material is formed by hydrogen bond network between 1,3,5-tris-(4-carboxyphenyl)benzene (H3BTB) and N,N-dimethylformamide (DMF) and by π–π stacking between the H3BTB moieties. The material can be viewed as a well-ordered array of cages, which are tight packed with each other so that the cages are inaccessible from outside. Thus, the host is practically nonporous. Despite the absence of permanent pathways connecting the empty cages, they are permeable to CO2 at high temperatures due to thermally activated molecular gating, and the weakly confined CO2 molecules in the cages allow direct detection by in situ single-crystal X-ray diffraction at 323 K. Variable-temperature in situ synchrotron powder X-ray diffraction studies also show that the CO2 sorption is reversible and driven by temperature increase. Solid-state magic angle spinning NMR defines the interactions of CO2 with the organic framework and dynamic motion of CO2 in cages. The reversible sorption is attributed to the dynamic motion of the DMF molecules combined with the axial motions/angular fluctuations of CO2 (a series of transient opening/closing of compartments enabling CO2 molecule passage), as revealed from NMR and simulations. This temperature-driven transient molecular gating can store gaseous molecules in ordered arrays toward unique collective properties and release them for ready use.

scholarly journals Electrochemical Oxidative Fluorination of an Oxide Perovskite

2020 ◽  
Author(s):  
Nicholas H. Bashian ◽  
Mateusz Zuba ◽  
Ahamed Irshad, ◽  
Shona Becwar ◽  
Julija Vinckeviciute ◽  
...  
Keyword(s):  
Density Functional ◽  
Room Temperature ◽  
Electrochemical Impedance ◽  
Density Functional Theory Calculations ◽  
Liquid Electrolyte ◽  
Magic Angle Spinning ◽  
Perovskite Oxide ◽  
Magic Angle ◽  
Alkali Cations ◽  
X Ray

<div>We report the successful electrochemical intercalation of F-ions into a densely packed perovskite oxide from a liquid electrolyte at room temperature. Using galvanostatic oxidation and electrochemical impedance spectroscopy coupled with operando X-ray diffraction, we show that roughly 0.5 equivalents of F-ions can be inserted onto the vacant A-site of the perovskite ReO3. Density functional theory calculations indicate that the intercalated phase is thermodynamically unfavorable compared to other less densely packed polymorphs of ReO3F. Pairing X-ray spectroscopy, neutron total scattering measurements, and magic-angle spinning 19F NMR confirms a rapid decomposition of the product on removal from the cell but nevertheless, these results clearly demonstrate that small anions like fluoride can be intercalated into solids as readily as alkali cations at room temperature, which opens new opportunities to electrochemically fluorinate many new materials.</div>

scholarly journals SYSU-6, A New 2-D Aluminophosphate Zeolite Layer Precursor

Molecules ◽  
2019 ◽  
Vol 24 (16) ◽  
pp. 2972 ◽  
Author(s):  
Jiang-Zhen Qiu ◽  
Long-Fei Wang ◽  
Jiuxing Jiang
Keyword(s):  
Electron Microscopy ◽  
Single Crystal ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
X Ray Diffraction ◽  
Structure Directing Agent ◽  
X Ray ◽  
Uv Raman ◽  
Angle Spinning ◽  
Inorganic Framework

Two-dimensional aluminophosphate is an important precursor of phosphate-based zeolites; a new Sun Yat-sen University No. 6 (SYSU-6) with |Hada|2[Al2(HPO4)(PO4)2] has been synthesized in the hydrothermal synthesis with organic structure-directing agent (OSDA) of N,N,3,5-tetramethyladamantan-1-amine. In this paper, SYSU-6 is characterized by single-crystal/powder X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray analysis, transmission electron microscopy, infrared and UV Raman spectroscopy, solid-state 27Al, 31P and 13C magic angle spinning (MAS) NMR spectra, and elemental analysis. The single-crystal X-ray diffraction structure indicates that SYSU-6 crystallized in the space group P21/n, with a = 8.4119(3), b = 36.9876(12), c = 12.5674(3), α = 90°, β = 108.6770(10)°, γ = 90°, V = 3704.3(2) Å3, Z = 4, R = 5.12%, for 8515 observed data (I > 2σ(I)). The structure has a new 4,12-ring layer framework topology linked by alternating AlO4 and PO4 tetrahedra. The organic molecules reside between the layers and are hydrogen-bonded to the inorganic framework. The new type of layer provides a greater opportunity to construct zeolite with novel topology.

scholarly journals Single-crystal X-ray diffraction and NMR crystallography of a 1:1 cocrystal of dithianon and pyrimethanil

2017 ◽  
Vol 73 (3) ◽  
pp. 149-156 ◽  
Author(s):  
Ann-Christin Pöppler ◽  
Emily K. Corlett ◽  
Harriet Pearce ◽  
Mark P. Seymour ◽  
Matthew Reid ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Chemical Shifts ◽  
Magic Angle Spinning ◽  
Mas Nmr ◽  
Double Quantum ◽  
Magic Angle ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nmr Crystallography

A single-crystal X-ray diffraction structure of a 1:1 cocrystal of two fungicides, namely dithianon (DI) and pyrimethanil (PM), is reported [systematic name: 5,10-dioxo-5H,10H-naphtho[2,3-b][1,4]dithiine-2,3-dicarbonitrile–4,6-dimethyl-N-phenylpyrimidin-2-amine (1/1), C14H4N2O2S2·C12H13N2]. Following an NMR crystallography approach, experimental solid-state magic angle spinning (MAS) NMR spectra are presented together with GIPAW (gauge-including projector augmented wave) calculations of NMR chemical shieldings. Specifically, experimental 1H and 13C chemical shifts are determined from two-dimensional 1H–13C MAS NMR correlation spectra recorded with short and longer contact times so as to probe one-bond C—H connectivities and longer-range C...H proximities, whereas H...H proximities are identified in a 1H double-quantum (DQ) MAS NMR spectrum. The performing of separate GIPAW calculations for the full periodic crystal structure and for isolated molecules allows the determination of the change in chemical shift upon going from an isolated molecule to the full crystal structure. For the 1H NMR chemical shifts, changes of 3.6 and 2.0 ppm correspond to intermolecular N—H...O and C—H...O hydrogen bonding, while changes of −2.7 and −1.5 ppm are due to ring current effects associated with C—H...π interactions. Even though there is a close intermolecular S...O distance of 3.10 Å, it is of note that the molecule-to-crystal chemical shifts for the involved sulfur or oxygen nuclei are small.

On new ternary equiatomic scandium transition metal aluminum compounds ScTAl with T = Cr, Ru, Ag, Re, Pt, and Au

2016 ◽  
Vol 71 (5) ◽  
pp. 553-566 ◽  
Author(s):  
Mathis Radzieowski ◽  
Christopher Benndorf ◽  
Sandra Haverkamp ◽  
Hellmut Eckert ◽  
Oliver Janka
Keyword(s):  
Transition Metal ◽  
Single Crystal ◽  
Structural Features ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
X Ray ◽  
Metal Aluminum ◽  
Aluminum Compounds ◽  
Angle Spinning ◽  
Metal Aluminides

AbstractThe new equiatomic scandium transition metal aluminides ScTAl for T = Cr, Ru, Ag, Re, Pt, and Au were obtained by arc-melting of the elements followed by subsequent annealing for crystal growth. The samples were studied by powder and single crystal X-ray diffraction. The structures of three compounds were refined from single crystal X-ray diffractometer data: ScCrAl, MgZn2 type, P63/mmc, a = 525.77(3), c = 858.68(5) pm, R1 = 0.0188, wR2 = 0.0485, 204 F2 values, 13 variables, ScPtAl, TiNiSi type, Pnma, a = 642.83(4), b = 428.96(2), c = 754.54(5) pm, R1 = 0.0326, wR2 = 0.0458, 448 F2 values, 20 variables and ScAuAl, HfRhSn type, P6̅2c, a = 722.88(4), c = 724.15(4) pm, R1 = 0.0316, wR2 = 0.0653, 512 F2 values, 18 variables. Phase pure samples of all compounds were furthermore investigated by magnetic susceptibility measurements, and Pauli-paramagnetism but no superconductivity was observed down to 2.1 K for all of them. The local structural features and disordering phenomena have been characterized by 27Al and 45Sc magic angle spinning (MAS) and static NMR spectroscopic investigations.

scholarly journals Structural Trends and Solid-Solutions Based on the Crystal Chemistry of Two Hausmannite (Mn3O4) Samples from the Kalahari Manganese Field

Minerals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 343 ◽  
Author(s):  
Sytle M. Antao ◽  
Laura A. Cruickshank ◽  
Kaveer S. Hazrah
Keyword(s):  
Single Crystal ◽  
Crystal Chemistry ◽  
Structure Refinement ◽  
Site Occupancy ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Jahn Teller

The crystal chemistry of two hausmannite samples from the Kalahari manganese field (KMF), South Africa, was studied using electron-probe microanalysis (EPMA), single-crystal X-ray diffraction (SCXRD) for sample-a, and high-resolution powder X-ray diffraction (HRPXRD) for sample-b, and a synthetic Mn3O4 (97% purity) sample-c as a reference point. Hausmannite samples from the KMF were reported to be either magnetic or non-magnetic with a general formula AB2O4. The EPMA composition for sample-a is [Mn2+0.88Mg2+0.11Fe2+0.01]Σ1.00Mn3+2.00O4 compared to Mn2+Mn3+2O4 obtained by refinement. The single-crystal structure refinement in the tetragonal space group I41/amd gave R1 = 0.0215 for 669 independently observed reflections. The unit-cell parameters are a = b = 5.7556(6), c = 9.443(1) Å, and V = 312.80(7) Å3. The Jahn–Teller elongated Mn3+O6 octahedron of the M site consists of M–O × 4 = 1.9272(5), M–O × 2 = 2.2843(7), and an average <M–O>[6] = 2.0462(2) Å, whereas the Mn2+O4 tetrahedron of the T site has T–O × 4 = 2.0367(8) Å. The site occupancy factors (sof) are M(sof) = 1.0 Mn (fixed, thereafter) and T(sof) = 1.0008(2) Mn. The EPMA composition for sample-b is [Mn0.99Mg0.01](Mn1.52Fe0.48)O4. The Rietveld refinement gave R (F2) = 0.0368. The unit-cell parameters are a = b = 5.78144(1), c = 9.38346(3) Å, and V = 313.642(1) Å3. The octahedron has M–O × 4 = 1.9364(3), M–O × 2 = 2.2595(6), and average <M–O>[6] = 2.0441(2) Å, whereas T–O × 4 = 2.0438(5) Å. The refinement gave T(sof) = 0.820(9) Mn2+ + 0.180(9) Fe2+ and M(sof) = 0.940(5) Mn3+ + 0.060(5) Fe3+. Samples-a and -b are normal spinels with different amounts of substitutions at the M and T sites. The Jahn–Teller elongation, Δ(M–O), is smaller in sample-b because atom substitutions relieve strain compared to pure Mn3O4.

The crystal structure of rabejacite, the Ca2+-dominant member of the zippeite group

2014 ◽  
Vol 78 (5) ◽  
pp. 1249-1264 ◽  
Author(s):  
J. Plášil ◽  
M. Dušek ◽  
J. Čejka ◽  
J. Sejkora
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Crystal Chemistry ◽  
Structure Refinement ◽  
Structural Formula ◽  
Crystal Data ◽  
Triclinic Space Group ◽  
X Ray ◽  
Rich Variety ◽  
Dominant Member

AbstractThe crystal structure of rabejacite from Jáchymov, ideally Ca2[(UO2)4O4(SO4)2](H2O)8, was solved by charge flipping from single-crystal data and refined to R1 = 11.94% for 1422 unique observed reflections [I > 3σ(I)]. According to single-crystal X-ray data, rabejacite is triclinic, space group P1̄ , with a = 8.7434(11), b = 8.309(3), c = 8.8693(10) Å , a = 77.86(2), b = 104.635(11), g = 82.935(18)°, V = 598.8(3) A˚ 3 and Z = 1, with Dcalc = 4.325 g cm–3. The structure refinement proved that rabejacite is related to the zippeite group of minerals, as it is based upon the structural sheets of the zippeite topology of composition [(UO2)4O4(SO4)2]4–. Located in the interlayer between the sheets, which are stacked perpendicular to [010], are Ca2+ cations and H2O groups. Ca2+ ions are [7]-coordinated, by three uranyl O atoms from adjacent sheets and four H2O groups. An additional H2O group, which is not bonded directly to any cation, is located in the interlayer. Along with rabejacite, its Cu-rich variety was found in the specimens examined and characterized structurally. Its crystal structure (R1 = 10.15% for 1049 reflections with I > 3s(I)) is practically the same as that of rabejacite, but there is an additional Cu2+ site located in between pairs of Ca polyhedra. The structural formula is (Ca1.56Cu0.40)Σ1.90[(UO2)4O4(SO4)2](H2O)8, Z = 1. Its existence suggests a greater diversity in zippeite crystal chemistry than was thought previously and also the possibility of a new Cu2+-dominant zippeite mineral besides pseudojohannite.

scholarly journals Electrochemical Oxidative Fluorination of an Oxide Perovskite

2020 ◽  
Author(s):  
Nicholas H. Bashian ◽  
Mateusz Zuba ◽  
Ahamed Irshad, ◽  
Shona Becwar ◽  
Julija Vinckeviciute ◽  
...  
Keyword(s):  
Density Functional ◽  
Room Temperature ◽  
Electrochemical Impedance ◽  
Density Functional Theory Calculations ◽  
Liquid Electrolyte ◽  
Magic Angle Spinning ◽  
Perovskite Oxide ◽  
Magic Angle ◽  
Alkali Cations ◽  
X Ray

<div>We report the successful electrochemical intercalation of F-ions into a densely packed perovskite oxide from a liquid electrolyte at room temperature. Using galvanostatic oxidation and electrochemical impedance spectroscopy coupled with operando X-ray diffraction, we show that roughly 0.5 equivalents of F-ions can be inserted onto the vacant A-site of the perovskite ReO3. Density functional theory calculations indicate that the intercalated phase is thermodynamically unfavorable compared to other less densely packed polymorphs of ReO3F. Pairing X-ray spectroscopy, neutron total scattering measurements, and magic-angle spinning 19F NMR confirms a rapid decomposition of the product on removal from the cell but nevertheless, these results clearly demonstrate that small anions like fluoride can be intercalated into solids as readily as alkali cations at room temperature, which opens new opportunities to electrochemically fluorinate many new materials.</div>

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