scholarly journals Cimetidine, C10H16N6S, form C: crystal structure and modelling of polytypes using the superspace approach

2013 ◽  
Vol 46 (1) ◽  
pp. 99-107 ◽  
Author(s):  
Alla Arakcheeva ◽  
Philip Pattison ◽  
Annette Bauer-Brandl ◽  
Henrik Birkedal ◽  
Gervais Chapuis
Keyword(s):  
Crystal Structure ◽  
Single Molecule ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
X Ray ◽  
Large Lattice ◽  
H2 Antagonist ◽  
Powder Samples ◽  
Diffraction Patterns ◽  
Primary Variable

The H2 antagonist cimetidine forms many polymorphs, several of which have resisted structural analysis thus far. Using single-crystal X-ray measurements obtained from synchrotron radiation, the crystal structure of cimetidine form C has been solved. This layered structure crystallizes in space groupC2/cwith an unusually large lattice parameter,a= 82.904 Å. The thickness of each layerLis equal toa′ =a/6 = 13.82 Å, anda= 6a′ originates from a sixfoldLLLL′L′L′ sequence withLandL′ differing by 0.5b. This packing is reminiscent of polytypic stacking in metals. A (3 + 1)-dimensional superspace model is derived and used to explain and predict many polytypic modifications. This model is characterized by (i) the (3 + 1)-dimensional symmetry groupX2/c(α0γ)00, whereX= 0\textstyle{1 \over 2}0\textstyle{1 \over 2}; (ii) the lattice parametera′ and modulation vectorq= 1/n(a′*); (iii) the atomic positions of a single molecule of cimetidine form C; (iv) the primary variable, 1/n. The model reproduces the previously solved structure, the 6M polytype, and generates the related polytypesnM with lattice parameteranM =na′ forn= 1, 2, 3, 4 and 5. A comparison of powder X-ray diffraction patterns available for cimetidine form C with those simulated for thenM polytypes suggests that the powder samples published previously probably contain a mixture of various polytypes.

Structure and Magnetocaloric Effect of B-Doped Mn-Fe-P-Si Compounds

2021 ◽  
Vol 323 ◽  
pp. 152-158
Author(s):  
Shou Yuan Xing ◽  
Song Lin ◽  
Zhi Qiang Song ◽  
Zhi Qiang Ou
Keyword(s):  
Crystal Structure ◽  
Curie Temperature ◽  
Lattice Parameter ◽  
Magnetic Entropy ◽  
Field Change ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Patterns ◽  
P Type ◽  
Type Crystal

We reported the structural, magnetic and magenetocaloric properties of Mn1.25Fe0.75P0. 50Si0.50Bx(x = 0.01, 0.02 and 0.04) X-ray diffraction patterns show that all compounds crystallize in the hexagonal Fe2P-type crystal structure. Lattice parameter a increases while c decreases with increasing B contents. The Curie temperature of the compounds have been determined, the values are 219, 268 and 323.2 K for x = 0.01, 0.02, 0.04, respectively. The maximum magnetic entropy changes in a field change of 0~1.5 T are 6.1, 5.3 and 3.5J/kg·K for x = 0.01, 0.02 and 0.04, respectively.

scholarly journals Diffraction Pattern Simulation of Crystal Structure towards the Ionic Radius Changes Via Vesta Program

2019 ◽  
Vol 1 (2) ◽  
pp. 132-139
Author(s):  
Ari Sulistyo Rini
Keyword(s):  
Crystal Structure ◽  
Diffraction Pattern ◽  
Ionic Radius ◽  
Lattice Parameter ◽  
Peak Position ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structure Information ◽  
Diffraction Patterns ◽  
The Relationship

The Simulations of X-ray diffraction patterns of MgO, BaO and ZnS ceramics were successfully performed by VESTA program, based on the crystal structures visualization. The aim of this research was to obtain the relationship between ionic radius to the diffraction pattern. The X-ray diffraction pattern was generated from visualization of the crystal structure. The crystal structure information was obtained from JCPDS data which contained lattice parameter, atomic coordinate and the space group. The X-ray diffraction pattern parameters which are taken into account in this research are diffraction angle of 2 Theta and Intensity. The results indicated that the peak position and intensity of the diffraction pattern are influenced by ionic radius of the cations. Structural transformation was also detected from this simulation.

scholarly journals Deep learning for visualization and novelty detection in large X-ray diffraction datasets

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Lars Banko ◽  
Phillip M. Maffettone ◽  
Dennis Naujoks ◽  
Daniel Olds ◽  
Alfred Ludwig
Keyword(s):  
Thin Film ◽  
Crystal Structure ◽  
Artificial Intelligence ◽  
Deep Learning ◽  
Novelty Detection ◽  
Structural Similarity ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Patterns ◽  
Post Hoc

AbstractWe apply variational autoencoders (VAE) to X-ray diffraction (XRD) data analysis on both simulated and experimental thin-film data. We show that crystal structure representations learned by a VAE reveal latent information, such as the structural similarity of textured diffraction patterns. While other artificial intelligence (AI) agents are effective at classifying XRD data into known phases, a similarly conditioned VAE is uniquely effective at knowing what it doesn’t know: it can rapidly identify data outside the distribution it was trained on, such as novel phases and mixtures. These capabilities demonstrate that a VAE is a valuable AI agent for aiding materials discovery and understanding XRD measurements both ‘on-the-fly’ and during post hoc analysis.

CRYSTAL STRUCTURE OF ZIRCONIUM TRICHLORIDE

1964 ◽  
Vol 42 (10) ◽  
pp. 1886-1889 ◽  
Author(s):  
B. Swaroop ◽  
S. N. Flengas
Keyword(s):  
Crystal Structure ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Main Cell ◽  
Diffraction Patterns

The crystal structure of zirconium trichloride was determined from X-ray diffraction patterns. Zirconium trichloride belongs to the [Formula: see text]space group. The dimensions of the main cell at room temperature are: a = 5.961 ± 0.005 Å and c = 9.669 ± 0.005 Å.The density of zirconium trichloride was measured and gave the value of 2.281 ± 0.075 g/cm3 while, from the X-ray calculations, the value was found to be 2.205 g/cm3.

scholarly journals VISUALISASI STRUKTUR KRISTAL KERAMIK PEROVSKITE MENGGUNAKAN VESTA

2018 ◽  
Vol 15 (1) ◽  
pp. 46
Author(s):  
Sundami Restiana ◽  
Ari Sulistyo Rini
Keyword(s):  
Crystal Structure ◽  
Diffraction Pattern ◽  
Critical Concentration ◽  
Ceramic Materials ◽  
Lattice Parameter ◽  
Peak Position ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structure Information ◽  
Software Program

Visualization of crystal structures and simulation of X-ray diffraction patterns of perovskite ceramic was successfully performed by VESTA software programs. The purpose of this research is to obtain the relation of lattice parameter, and composition to the diffraction pattern. The software program produces crystal structure information and a representative X-ray diffraction pattern for the ceramic materials. The program needs several input parameters such as the coordinates of each constituent atom, lattice parameters, and space symmetry. The obtained output of the software program are in the form of diffraction pattern graph and crystal structure data which gives the description of the profile and type (phase) of ceramic material. The results showed that the peak position and intensity of the diffraction pattern are influenced by the arrangement of  the atoms within the unit cell. The addition of impurity atoms such as Sr on the Ba side in BaTiO3 causes the BaTiO3 structure changes from Orthorombic (a≠b≠c) to Tetragonal (a=b≠c) structure. Based on the simulation, it can be predicted that the critical concentration of the change of structure occur at Sr concentration about 0.4.

Structural and phase equilibria studies in the system Pt-Fe-Cu and the occurrence of tulameenite (Pt2FeCu)

1985 ◽  
Vol 49 (353) ◽  
pp. 547-554 ◽  
Author(s):  
M. Shahmiri ◽  
S. Murphy ◽  
D. J. Vaughan
Keyword(s):  
Crystal Structure ◽  
Solid Solution ◽  
Critical Temperature ◽  
Grain Boundary ◽  
Phase Region ◽  
X Ray Diffraction ◽  
Two Phase ◽  
Slow Cooling ◽  
X Ray ◽  
Diffraction Patterns

AbstractThe crystal structure and compositional limits of the ternary compound Pt2FeCu (tulameenite), formed either by quenching from above the critical temperature of 1178°C or by slow cooling, have been investigated using X-ray diffraction, transmission electron microscopy, differential thermal analysis and electron probe microanalysis.The crystal structure of Pt2FeCu, established using electron density maps constructed from the measured and calculated intensities of X-ray diffraction patterns of powdered specimens, has the (000) and (½½0) lattice sites occupied by Pt atoms and the (½0½) and (0½½) sites occupied by either Cu or Fe atoms in a random manner. The resulting face-centred tetragonal structure undergoes a disordering transformation at the critical temperature to a postulated non-quenchable face-centred cubic structure. Stresses on quenching, arising from the ordering reaction, are relieved by twinning along {101} planes or by recrystallization along with deformation twinning; always involving grain boundary fracturing.Phase relations in the system Pt-Fe-Cu have been investigated through the construction of isothermal sections at 1000 and 600°C. At 1000°C there is an extensive single phase region of solid solution around Pt2FeCu and extending to the binary composition PtFe. At 600°C the composition Pt2FeCu lies just outside this now reduced area of solid solution in a two-phase field. Comparison of the experimental results with data for tulameenite suggests that some observed compositions may be metastably preserved. The occurrence of fine veinlets of silicate or other gangue minerals in tulameenite is suggested to result from grain boundary fracturing on cooling below the critical temperature of 1178°C and to be evidence of a magmatic origin.

Structural and optical properties of Ba(Co1−xZnx)SiO4 (x = 0.2, 0.4, 0.6, 0.8)

2019 ◽  
Vol 34 (3) ◽  
pp. 242-250 ◽  
Author(s):  
J. Anike ◽  
R. Derbeshi ◽  
W. Wong-Ng ◽  
W. Liu ◽  
D. Windover ◽  
...  
Keyword(s):  
Lattice Parameter ◽  
X Ray Diffraction ◽  
Powder Diffraction File ◽  
Visible Absorption ◽  
X Ray ◽  
Lattice Volume ◽  
Uv Visible ◽  
Diffraction Patterns ◽  
Pattern Determination ◽  
Bright Blue

Structural characterization and X-ray reference powder pattern determination have been conducted for the Co- and Zn-containing tridymite derivatives Ba(Co1−xZnx)SiO4 (x = 0.2, 0.4, 0.6, 0.8). The bright blue series of Ba(Co1−xZnx)SiO4 crystallized in the hexagonal P63 space group (No. 173), with Z = 6. While the lattice parameter “a” decreases from 9.126 (2) Å to 9.10374(6) Å from x = 0.2 to 0.8, the lattice parameter “c” increases from 8.69477(12) Å to 8.72200(10) Å, respectively. Apparently, despite the similarity of ionic sizes of Zn2+ and Co2+, these opposing trends are due to the framework tetrahedral tilting of (ZnCo)O4. The lattice volume, V, remains comparable between 626.27 Å3 and 626.017 (7) Å3 from x = 0 to x = 0.8. UV-visible absorption spectrum measurements indicate the band gap of these two materials to be ≈3.3 and ≈3.5 eV, respectively, therefore potential UV photocatalytic materials. Reference powder X-ray diffraction patterns of these compounds have been submitted to be included in the Powder Diffraction File (PDF).

The X-Ray Powder Diffraction Patterns and Crystal Structure for Al2M3Y(M=Cu, Ni)

2014 ◽  
Vol 950 ◽  
pp. 48-52
Author(s):  
De Gui Li ◽  
Ming Qin ◽  
Liu Qing Liang ◽  
Zhao Lu ◽  
Shu Hui Liu ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Hexagonal Structure ◽  
Argon Atmosphere ◽  
X Ray Diffraction ◽  
High Quality ◽  
X Ray ◽  
Arc Melting ◽  
Diffraction Patterns

The Al2M3Y(M=Cu, Ni) compound was synthesized by arc melting under argon atmosphere. The high-quality powder X-ray diffraction data of Al2M3Y have been presented. The refinement of the X-ray diffraction patterns for the Al2M3Y compound show that the Al2M3Y has hexagonal structure, space groupP6/mmm(No.191), with a = b = 5.1618(2) Å, c = 4.1434(1) Å,V= 95.6 Å3,Z= 1,ڑx= 5.7922 g/cm3,F30= 155.5(0.0057, 34), RIR = 2.31 for Al2Cu3Y, and with a = b = 5.0399(1) Å, c = 4.0726(1) Å,V= 89.59 Å3,Z= 1,ڑx= 5.9118 g/cm3,F30= 135.7(0.0072, 30), RIR = 2.54 for Al2Ni3Y.

Structural and electrical properties of Cu-doped Ni–Zn nanocrystalline ferrites for MLCI applications

2017 ◽  
Vol 31 (33) ◽  
pp. 1750318 ◽  
Author(s):  
D. Venkatesh ◽  
K. V. Ramesh
Keyword(s):  
Electrical Properties ◽  
Cation Distribution ◽  
Tetrahedral Site ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
Sem Images ◽  
X Ray ◽  
Structural And Electrical Properties ◽  
Phase Spinel ◽  
Diffraction Patterns

Polycrystalline Cu substituted Ni–Zn ferrites with chemical composition Ni[Formula: see text]Zn[Formula: see text]-Cu[Formula: see text]Fe2O4 (x = 0.00 to 0.25 in steps of 0.05) have been prepared by citrate gel autocombustion method. The samples for electrical properties have been sintered at 900[Formula: see text]C for 4 h. The X-ray diffraction patterns of all samples indicate the formation of single phase spinel cubic structure. The value of lattice parameter is decreases with increasing Cu concentration. The estimated cation distribution can be derived from X-ray diffraction intensity calculations and IR spectra. The tetrahedral and octahedral bond lengths, bond angles, cation–cation and cation–anion distances were calculated by using experimental lattice parameter and oxygen positional parameters. It is observed that Cu ions are distributed in octahedral site and subsequently Ni and Fe ions in tetrahedral site. The grain size of all samples has been calculated by Scanning Electron Microscopy (SEM) images. The variations in DC electrical resistivity and dielectric constant have been explained on the basis of proposed cation distribution.

Studied on Structural Characterization of Lanthanum Doped Barium Titanium Ceramics

2015 ◽  
Vol 819 ◽  
pp. 198-203
Author(s):  
Nur Farahin Abdul Hamid ◽  
Rozana Aina Maulat Osman ◽  
Mohd Sobri Idris ◽  
Tze Qing Tan
Keyword(s):  
Crystal Structure ◽  
Lattice Parameter ◽  
Phase Changes ◽  
X Ray Diffraction ◽  
X Ray ◽  
Tetragonal Crystal ◽  
Tetragonal Crystal Structure ◽  
La Doped ◽  
Conventional Solid State Synthesis

La-doped barium titanate (BaTiO3) was prepared using conventional solid state synthesis route. All peaks for sample x=0 are approaching the phase pure of BaTiO3 structure with tetragonal crystal structure (P4mm). Sintering of pressed powder are performed at 1300oC, 1400oC and 1450oC for overnight for pure BaTiO3 and 1350oC for 3 days for BaTiO3 doped lanthanum with intermittent grinding. Phase transition was studied by different x composition. The changes in the crystal structure of the composition x=0.1 and 0.2 were detected by using X-ray diffraction (XRD). The phase changes between tetragonal-cubic and cubic-tetragonal depending on the temperature. Rietveld Refinement analysis is carried out to determine the lattice parameter and unit cell for BaTiO3.

Sign in / Sign up

Export Citation Format

Share Document