scholarly journals Structure and microstructure characterization of the La2SrB10O19 glass-ceramics

2019 ◽  
Vol 51 (4) ◽  
pp. 389-399
Author(s):  
Jovica Stojanovic ◽  
Sonja Smiljanic ◽  
Snezana Grujic ◽  
Predrag Vulic ◽  
Srdjan Matijasevic ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Borate Glass ◽  
Rietveld Method ◽  
Glass Ceramics ◽  
Monoclinic Crystal ◽  
Monoclinic Crystal Structure ◽  
Strontium Borate ◽  
Lanthanum Strontium ◽  
Structure And Microstructure

The crystal structure of new lanthanum strontium borate glass-ceramics was refined by the Rietveld method. The results showed that La2SrB10O19 has the monoclinic crystal structure, space group C2 (No. 5) with a = 11.1170(6), b = 6.5667(3), c = 9.2363(3) ?, ? = 91.481?, V = 674.04(7) ?3, two formula units per unit-cell, and density 3.830 g cm?3. The main building units of the crystal structure are BO4 tetrahedra and BO3 triangles. Clusters composed of [B5O12] form an infinite double layer running perpendicular to the c-axis. Lanthanum atoms, situated in [B5O12]n layers, are coordinated with 10 oxygen atom in a form of LaO10 polyhedra, while Sr atoms, located between [B5O12]n layers, are coordinated with 8 oxygen atoms in a form of SrO8 polyhedra. Microstructural measurements contain both crystallite domain sizes and microstrain calculations obtained by the Warren-Averbach and the simplified integral-breadth methods.

Preparation, Crystal Structure, and Properties of the Lanthanoid Carbides Ln4C7 with Ln = Ho, Er, Tm, and Lu

1996 ◽  
Vol 51 (5) ◽  
pp. 646-654 ◽  
Author(s):  
Ralf Czekalla ◽  
Wolfgang Jeitschko ◽  
Rolf-Dieter Hoffmann ◽  
Helmut Rabeneck
Keyword(s):  
Crystal Structure ◽  
Rietveld Method ◽  
Magnetic Ordering ◽  
Monoclinic Crystal ◽  
X Ray ◽  
Neutron Powder Diffraction Data ◽  
Monoclinic Crystal Structure ◽  
Arc Melting ◽  
Structure Factors ◽  
Hydrolysis Of

The isotypic carbides Ln4C7 (Ln = Ho, Er, Tm, Lu) were prepared by arc-melting of the elemental components, followed by annealing at 1300 °C. The positions of the metal and of some carbon atoms of the monoclinic crystal structure of LU4C7 were determined from X-ray powder data, and the last carbon positions were found and refined from neutron powder diffraction data: P21/c, a = 360.4(1), b = 1351.4(3), c = 629.0(2) pm, β = 104.97(2)°, Z = 2, R = 0.026 for 429 structure factors and 15 positional parameters. The structure contains isolated carbon atoms with octahedral lutetium coordination and linear C3-units, with C-C bond lengths of 132(1) and 135(1) pm. This carbide may therefore be considered as derived from methane and propadiene. The hydrolysis of LU4C7 with distilled water yields mainly methane and propine, while the hydrolyses of the corresponding holmium and erbium carbides resulted in relatively large amounts of saturated and unsaturated C2-hydrocarbons in addition to the expected products methane and propine. The structure comprises two-dimensionally infinite NaCl-type building elements, which are separated by the C3-units. It may be described as a stacking variant of a previously reported structure of HO4C7, now designated as the a-modification. The Lu4C7-type β -modification was obtained at higher temperatures. Its structure was refined by the Rietveld method from X-ray powder data to a residual R = 0.037 for 320 F values and 15 positional parameters. Lu4C7 is Pauli paramagnetic; β -HO4C7 and Er4C7 show Curie-Weiss behavior with magnetic ordering temperatures of less than 20 K.

Novel aluminophosphate Na6[Al3P5O20] with the original microporous crystal structure established in the study of a pseudomerohedric microtwin

2021 ◽  
Vol 77 (2) ◽  
pp. 232-240
Author(s):  
Olga V. Yakubovich ◽  
Galina V. Kiriukhina ◽  
Anatoliy S. Volkov ◽  
Olga V. Dimitrova ◽  
Elena Yu. Borovikova
Keyword(s):  
Crystal Structure ◽  
Unit Cell Parameters ◽  
Monoclinic Crystal ◽  
Cell Parameters ◽  
Monoclinic Crystal Structure ◽  
Generalized Framework ◽  
Microporous Zeolite ◽  
Phosphate Groups ◽  
Framework Density

The synthesis and characterization of a new aluminophosphate, Na6[Al3P5O20], obtained as single crystals in the same experiment together with Cl-sodalite, Na8[Al6Si6O24]Cl2, is reported. Na6[Al3P5O20], with a strongly pseudo-orthorhombic lattice, is described by the monoclinic crystal structure established in the study of a pseudomerohedric microtwin. The design of Na6[Al3P5O20] can be interpreted as an alternative to sodalite, with a monoclinic (pseudo-orthorhombic) 2×4×1 super-structure and unit-cell parameters multiples of those of sodalite: a ≃ 2a s, b ≃ 4b s and c ≃ c s. The triperiodic framework is built by AlO6, AlO4 and PO4 polyhedra having vertex-bridging contacts. While all the oxygen vertices of the Al-centred octahedra and tetrahedra are shared with phosphate groups, some of the PO4 tetrahedra remain `pendant', e.g. containing vertices not shared with other polyhedra of the aluminophosphate construction. Na atoms occupy framework channels and cavities surrounded by eight-, six- and four-membered windows with maximal effective pore widths of 4.86 × 3.24 and 4.31 × 3.18 Å. The generalized framework density is equal to 19.8, which means that the compound may be classified as a microporous zeolite. The Na6[Al3P5O20] crystal structure is discussed as being formed from octahedral rods arranged in two perpendicular directions, similar to the rods elongated in one direction in the NASICON-type compounds, which have been intensively investigated as promising materials for batteries. Analogous properties can be expected for phases with a modified composition of the Na6Al3P5O20 topology, where the Al atoms at the centres of octahedra are replaced by Fe, V or Cr.

scholarly journals Crystal structure and characterization of magnesium carbonate chloride heptahydrate

2020 ◽  
Vol 76 (8) ◽  
pp. 741-745
Author(s):  
Christine Rincke ◽  
Horst Schmidt ◽  
Gernot Buth ◽  
Wolfgang Voigt
Keyword(s):  
Crystal Structure ◽  
Magnesium Carbonate ◽  
Chloride Ions ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
Monoclinic Crystal ◽  
Monoclinic Crystal Structure ◽  
Structure Solution ◽  
Concentrated Solution

MgCO3·MgCl2·7H2O is the only known neutral magnesium carbonate containing chloride ions at ambient conditions. According to the literature, only small and twinned crystals of this double salt could be synthesised in a concentrated solution of MgCl2. For the crystal structure solution, single-crystal diffraction was carried out at a synchrotron radiation source. The monoclinic crystal structure (space group Cc) exhibits double chains of MgO octahedra linked by corners, connected by carbonate units and water molecules. The chloride ions are positioned between these double chains parallel to the (100) plane. Dry MgCO3·MgCl2·7H2O decomposes in the air to chlorartinite, Mg2(OH)Cl(CO3)·nH2O (n = 2 or 3). This work includes an extensive characterization of the title compound by powder X-ray diffraction, thermal analysis, SEM and vibrational spectroscopy.

X-ray powder diffraction study of LiCrP2O7

2007 ◽  
Vol 63 (3) ◽  
pp. i70-i72 ◽  
Author(s):  
Ludmila S. Ivashkevich ◽  
Kirill A. Selevich ◽  
Anatoly I. Lesnikovich ◽  
Anatoly F. Selevich
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Rietveld Method ◽  
Three Dimensional ◽  
Powder Diffraction Data ◽  
Monoclinic Crystal ◽  
X Ray ◽  
Monoclinic Crystal Structure ◽  
Dimensional Network ◽  
Tetrahedral Environment

The monoclinic crystal structure of lithium chromium(III) diphosphate, LiCrP2O7, isotypic with other members of the series LiM IIIP2O7 (M III = Mn, Fe, V, Mo, Sc and In), was refined from laboratory X-ray powder diffraction data using the Rietveld method. The Cr3+ cation is bonded to six O atoms from five diphosphate anions to form a distorted octahedron. Links between the bent diphosphate anions and the Cr3+ cations result in a three-dimensional network, with tunnels filled by the Li+ cations in a considerably distorted tetrahedral environment of O atoms.

trans-Bis(O-ethylxanthato)bis(triphenylphosphine)ruthenium(III) hexafluorophosphate monohydrate

2006 ◽  
Vol 62 (5) ◽  
pp. m1077-m1078
Author(s):  
Yuko Ohuchi ◽  
Kyoko Noda ◽  
Takayoshi Suzuki ◽  
Kazuo Kashiwabara ◽  
Hideo D. Takagi
Keyword(s):  
Crystal Structure ◽  
Title Compound ◽  
Complex Cation ◽  
Orthorhombic Crystal ◽  
Monoclinic Crystal ◽  
Monoclinic Crystal Structure

In the monoclinic crystal structure of the title compound, trans-[Ru(C3H5OS2)2(C18H15P)2]PF6·H2O, the structure of the RuIII complex cation is very similar to that in the orthorhombic crystal of the nonhydrated complex [Noda, Ohuchi, Hashimoto, Fujiki, Itoh, Iwatsuki, Noda, Suzuki, Kashiwabara & Takagi (2006), Inorg. Chem. 45, 1349–1355]. In the present crystal structure, the P—Ru—P bond axes of the complex cations are aligned parallel to the [101] direction.

Electron density, disorder and polymorphism: high-resolution diffraction studies of the highly polymorphic neuralgic drug carbamazepine

2016 ◽  
Vol 72 (1) ◽  
pp. 39-50 ◽  
Author(s):  
Ioana Sovago ◽  
Matthias J. Gutmann ◽  
Hans Martin Senn ◽  
Lynne H. Thomas ◽  
Chick C. Wilson ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Resolution ◽  
Diffraction Data ◽  
Structural Formula ◽  
Orthorhombic Crystal ◽  
Monoclinic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Space Group ◽  
X Ray ◽  
Monoclinic Crystal Structure

Analysis of neutron and high-resolution X-ray diffraction data on form (III) of carbamazepine at 100 K using the atoms in molecules (AIM) topological approach afforded excellent agreement between the experimental results and theoretical densities from the optimized gas-phase structure and from multipole modelling of static theoretical structure factors. The charge density analysis provides experimental confirmation of the partially localized π-bonding suggested by the conventional structural formula, but the evidence for any significant C—N π bonding is not strong. Hirshfeld atom refinement (HAR) gives H atom positional and anisotropic displacement parameters that agree very well with the neutron parameters. X-ray and neutron diffraction data on the dihydrate of carbemazepine strongly indicate a disordered orthorhombic crystal structure in the space groupCmca, rather than a monoclinic crystal structure in space groupP21/c. This disorder in the dihydrate structure has implications for both experimental and theoretical studies of polymorphism.

Crystal chemistry of inorganic compounds based on chains of oxocentered tetrahedra III. Crystal structure of georgbokiite, Cu5O2(SeO3)2Cl21

1999 ◽  
Vol 214 (3) ◽  
Author(s):  
S. V. Krivovichev ◽  
R. R. Shuvalov ◽  
T. F. Semenova ◽  
S. K. Filatov
Keyword(s):  
Crystal Structure ◽  
Chemical Composition ◽  
Crystal Chemistry ◽  
Inorganic Compounds ◽  
New Mineral ◽  
Monoclinic Crystal ◽  
Monoclinic Crystal Structure

AbstractThe monoclinic crystal structure of georgbokiite, a new mineral with the chemical composition Cu

scholarly journals The monoclinic crystal structure form of bacterioferritin fromE. coli

1996 ◽  
Vol 52 (a1) ◽  
pp. C177-C177
Author(s):  
M. Hospital ◽  
A. Dautant ◽  
J. Yariv ◽  
G. Précigoux ◽  
A. J. Kalb (Gilboa) ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Structure Form ◽  
Monoclinic Crystal ◽  
Monoclinic Crystal Structure
Sign in / Sign up

Export Citation Format

Share Document