scholarly journals Becquerelite mineral phase: crystal structure and thermodynamic and mechanical stability by using periodic DFT

RSC Advances ◽  
2018 ◽  
Vol 8 (43) ◽  
pp. 24599-24616 ◽  
Author(s):  
Francisco Colmenero ◽  
Ana María Fernández ◽  
Vicente Timón ◽  
Joaquin Cobos
Keyword(s):  
Crystal Structure ◽  
Mechanical Properties ◽  
Solid State ◽  
Mechanical Stability ◽  
Mineral Phase ◽  
Phase Crystal ◽  
Complete Study ◽  
First Time ◽  
Periodic Dft

The full crystal structure of becquerelite mineral phase was successfully determined using theoretical solid-state methods for the first time. Additionally, a complete study of its thermodynamic and mechanical properties and stability is reported.

scholarly journals SYNTHESIS OF ZINC SULFIDE RADIOLUMINESCENT PHOSPHORS WITH USE OF ELECTRONIC BEAM MODIFICATION AND INVESTIGATION OF THEIR PROPERTIES

2021 ◽  
Vol 58 ◽  
pp. 46-50
Author(s):  
Mikhail A. Shvindin ◽  
◽  
Vadim V. Bakhmetyev ◽  
Keyword(s):  
Crystal Structure ◽  
Experimental Data ◽  
Electron Beam ◽  
Solid State ◽  
Zinc Sulfide ◽  
Spectral Characteristics ◽  
Light Sources ◽  
Synthesis Conditions ◽  
Radioluminescent Light Sources ◽  
First Time

Synthesized recombination-type zinc sulfide phosphors used in solid-state radioluminescent light sources (SSRLS) are the object of the research. In the course of the study, experimental data were obtained for the first time on the effect of the amount of the incorporated activator on the brightness-spectral characteristics of radioluminescence upon excitation by β-radiation of tritium. Data were obtained on the changes in the radioluminescence parameters under various synthesis conditions, phase composition and electron-beam modification of the crystal structure of the initial phosphors. The results of the work make it possible to find the best light compositions for the use in solid-state radioluminescent light sources

scholarly journals The layered uranyl silicate mineral uranophane-β: crystal structure, mechanical properties, Raman spectrum and comparison with the α-polymorph

2019 ◽  
Vol 48 (44) ◽  
pp. 16722-16736 ◽  
Author(s):  
Francisco Colmenero ◽  
Jakub Plášil ◽  
Jiří Sejkora
Keyword(s):  
Crystal Structure ◽  
Mechanical Properties ◽  
Raman Spectrum ◽  
Solid State ◽  
Elastic Properties ◽  
First Principles ◽  
Silicate Mineral

The crystal structure, elastic properties and Raman spectrum of the calcium uranyl silicate pentahydrate mineral uranophane-β, are studied using first-principles solid-state methods and compared with the corresponding information for the α polymorph.

The Crystal Structure of cis-Chlorobis(triethylphosphine)-1,10-phenanthrolineplatinum(II) fluoroborate, (PtCl(PEt3)2(phen))BF4, a Complex Containing Monodentate 1,10-Phenanthroline

1974 ◽  
Vol 52 (8) ◽  
pp. 1367-1376 ◽  
Author(s):  
Gordon W. Bushnell ◽  
Keith R. Dixon ◽  
Masood A. Khan
Keyword(s):  
Crystal Structure ◽  
Nuclear Magnetic Resonance ◽  
Solid State ◽  
Magnetic Resonance ◽  
Interatomic Distances ◽  
Square Planar ◽  
Cell Dimensions ◽  
Tetragonal Pyramidal ◽  
R Value ◽  
First Time

The crystal structure of cis-chlorobis(triethylphosphine)-1,10-phenanthrolineplatinum(II) fluoroborate has been determined and refined to an R-value of 0.051. The space group is P21/c and the cell dimensions are a = 0.9215(2), b = 1.1991(3), c = 2.6832(6) nm, β = 99.38(3)°, with 4 molecules per unit cell. The interatomic distances to Pt are: Pt—N(1), 213.7(19); Pt—N(2), 284.3(20); Pt—P(1), 223.9(7); Pt—P(2), 224.1(6); Pt—Cl, 236.1(6) pm.The coordination number and geometry is discussed in terms of 5-coordinate tetragonal pyramidal and 4-coordinate square planar models, the latter being regarded as the more acceptable.Monodentate o-phenanthroline is thus observed for the first time in the solid state. The structure of the complex in solution is discussed with the aid of conductance and nuclear magnetic resonance results which suggest the possibility of a novel fluxional system.

Darstellung und Kristallstrukturanalyse von K3BiO3 und Rb3BiO3 / Synthesis and Crystal Structure Determination of K3BiO3 and Rb3BiO3

1997 ◽  
Vol 52 (9) ◽  
pp. 1031-1036 ◽  
Author(s):  
Nicola Zoche ◽  
Martin Jansen
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Single Crystal ◽  
Structure Determination ◽  
Solid State Reactions ◽  
Synthesis And Crystal Structure ◽  
X Ray ◽  
Binary Compounds ◽  
First Time

K3BiO3 and Rb3BiO3 have been synthesized for the first time by solid state reactions of the respective binary compounds. K3BiO3 was obtained from Bi2O3 and K2O at 550 °C, Rb3BiO3 from Bi2O3 and Rb2O at 650 °C. The compounds were structurally examined by single-crystal X -ray investigations (K3BiO3: I 4̅ 3 m, a = 1070.15(2) pm, Z = 8; Rb3BiO3: P 21 3, a = 875.48(2) pm, Z = 4). The structures reveal “isolated” BiO33- groups. While K3BiO3 is isostructural to Na3BiO3, Rb3BiO3 has the same crystal structure as Cs3BiO3.

Diastereotopic group recognition in the solid state — A unique intramolecular β-cyclodextrin inclusion complex

2001 ◽  
Vol 79 (11) ◽  
pp. 1806-1811
Author(s):  
Manfred T Reetz ◽  
Joachim Rudolph ◽  
Richard Goddard
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Inclusion Complex ◽  
Supramolecular Chemistry ◽  
Structure Analysis ◽  
Crystal Structure Analysis ◽  
Close Vicinity ◽  
Cyclodextrin Inclusion ◽  
Cyclodextrin Inclusion Complex ◽  
First Time

The phenomenon of diastereotopic group recognition has been structurally documented for the first time. A diphenylphosphine-modified β-cyclodextrin having two diastereotopic phenyl groups in close vicinity to the inner cavity of this host was prepared. The crystal structure analysis reveals selective intramolecular complexation of one of the two diastereotopic phenyl groups.Key words: supramolecular chemistry, stereotopic group recognition, cyclodextrins, intramolecular complexation.

Structure determination of the theophylline–nicotinamide cocrystal: a combined powder XRD, 1D solid-state NMR, and theoretical calculation study

CrystEngComm ◽  
2014 ◽  
Vol 16 (15) ◽  
pp. 3141-3147 ◽  
Author(s):  
Ping Li ◽  
Yueying Chu ◽  
Lin Wang ◽  
Robert M. Wenslow ◽  
Kaichao Yu ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Theoretical Calculation ◽  
Structure Determination ◽  
Solid State Nmr ◽  
Powder Xrd ◽  
First Time

The crystal structure of the theophylline–nicotinamide cocrystal is determined for the first time by using a combined multi-technique approach.

The surprisingly elusive crystal structure of sodium metabisulfite

2004 ◽  
Vol 60 (2) ◽  
pp. 155-162 ◽  
Author(s):  
Kay L. Carter ◽  
Tasneem A. Siddiquee ◽  
Kristen L. Murphy ◽  
Dennis W. Bennett
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Low Temperature ◽  
Unit Cell ◽  
Sodium Metabisulfite ◽  
Asymmetric Unit ◽  
Space Group ◽  
Crystal Fragment ◽  
First Time ◽  
Correct Structure

The crystal structure of Na2S2O5, a simple and common ionic compound, is reported here for the first time. The crystals form non-merohedral twins, with the twin domains related by a twofold axis which bisects the angle between the a and c axes of each unit cell. The structure was determined from a single-crystal fragment of a twinned crystal that had undergone cleavage along the twin boundary. In addition to the problems associated with twinning, space-group determination proved difficult as well, with the structure initially determined in the P21 space group appearing to be disordered with two rotational conformers of the metabisulfite ion occupying equivalent sites in the lattice. An analysis at low temperature provided new weak reflections which were inconsistent with the original unit cell, but indexed to the correct unit cell, allowing for space group and crystal structure determination. The apparent structure, which appeared disordered in P21, seems to have resulted from an apparently fortuitous superposition of two conformationally inequivalent S2O_5^{2-} anions in the asymmetric unit of the correct structure in the P21/n space group. The metabisulfite ions in this structure do not adopt the Cs geometry observed in previously determined crystal structures containing S2O_5^{2-}. The structures of both ions in the asymmetric unit are effectively conformational mirror images of one another with two of the O atoms on each S atom in the ion approaching an eclipsed geometry. This observation provides further evidence that the structures of sulfur-oxy anions in the solid state are dictated mainly by interionic coulombic forces rather than by intraionic bonding interactions

Superamidines 2. Synthesis of the bulky ligand N,N'-bis-(2,6-diisopropylphenyl)-trifluoroacetamidine and its molybdenum carbonyl complex

2000 ◽  
Vol 78 (5) ◽  
pp. 583-589 ◽  
Author(s):  
René T Boeré ◽  
Vicki Klassen ◽  
Gotthelf Wolmershäuser
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Nmr Spectroscopy ◽  
Thermal Reaction ◽  
Carbonyl Complex ◽  
X Ray ◽  
Metal Metal ◽  
Molybdenum Carbonyl ◽  
Bulky Ligand ◽  
First Time

N,N'-bis-(2,6-diisopropylphenyl)trifluoroacetamidine has been prepared for the first time from 2,6-diisopropylaniline and the trifluoroacylation reagent TFAP via the imidoylchloride. The crystal structure of the amidine was determined, indicating that it crystallizes in the Z-anti tautomer, in contrast to the nonfluorinated analogue, which is E-anti in the solid state. In solution, as indicated by NMR spectroscopy, it exists in two isomeric forms. The amidine reacts with Mo(CO)6 to produce a coordination complex with Mo(CO)3 in which the ligand is also in the Z-anti geometry, the metal is η6-coordinated to the imino-2,6-diisopropylphenyl ring, and the amino N-H unit is directed towards the metal, as determined by a single-crystal X-ray structure. Unlike the analogous nonfluorinated acetamidine, there is no indication of an intermediate in which the neutral amidine is coordinated in a monodentate fashion to an Mo(CO)5 unit, which we now attribute to the predominant geometry of the ligand, both in the solid state and in solution, being Z-anti. The high steric bulk of this superamidine ligand apparently prevents the formation of a metal-metal bonded Mo2(amidinate)4 as observed previously in a redox reaction between N,N'-diphenylbenzamidine and Mo(CO)6 under similar thermal reaction conditions.Key words: trifluoromethyl, superamidine, amidine, molybdenum, carbonyl, coordination.

Mechanical behavior of MgO-whisker reinforced (Bi, Pb)2Sr2Ca2Cu3Oy high-temperature superconducting composite

1996 ◽  
Vol 11 (7) ◽  
pp. 1645-1652 ◽  
Author(s):  
Y. S. Yuan ◽  
M. S. Wong ◽  
S. S. Wang
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Solid State ◽  
Mechanical Behavior ◽  
Elastic Properties ◽  
High Temperature Superconductors ◽  
Processing Method ◽  
Superconducting Properties ◽  
First Time ◽  
State Processing

The inherently weak mechanical properties of bulk monolithic high-temperature superconductors (HTS) have been a concern. Properly selected reinforcements in fiber and whisker forms have been introduced to the HTS ceramics to improve their mechanical properties. In this paper, mechanical behavior of a MgO-whisker reinforced Pb-doped Bi-2223 (BPSCCO) HTS composite fabricated by a solid-state processing method is studied. The (MgO)w/BPSCCO HTS composite has been shown to exhibit excellent superconducting properties. Elastic properties, strengths, and notched fracture toughnesses of both the monolithic BPSCCO and the (MgO)w/BPSCCO HTS composite are investigated. Detailed mechanical properties are reported for the first time for the (MgO)w/BPSCCO HTS composite. Mechanisms of strengthening and toughening in the MgO-whisker-reinforced HTS composite are also discussed.

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