scholarly journals Automated prediction of lattice parameters from X-ray powder diffraction patterns

2021 ◽  
Vol 54 (6) ◽  
Author(s):  
Sathya R. Chitturi ◽  
Daniel Ratner ◽  
Richard C. Walroth ◽  
Vivek Thampy ◽  
Evan J. Reed ◽  
...  
Keyword(s):  
Accurate Determination ◽  
Model Performance ◽  
Lattice Parameter ◽  
Unit Cell ◽  
Lattice Parameters ◽  
Parameter Estimates ◽  
Inorganic Crystal Structure Database ◽  
X Ray ◽  
Crystal System ◽  
Peak Broadening

A key step in the analysis of powder X-ray diffraction (PXRD) data is the accurate determination of unit-cell lattice parameters. This step often requires significant human intervention and is a bottleneck that hinders efforts towards automated analysis. This work develops a series of one-dimensional convolutional neural networks (1D-CNNs) trained to provide lattice parameter estimates for each crystal system. A mean absolute percentage error of approximately 10% is achieved for each crystal system, which corresponds to a 100- to 1000-fold reduction in lattice parameter search space volume. The models learn from nearly one million crystal structures contained within the Inorganic Crystal Structure Database and the Cambridge Structural Database and, due to the nature of these two complimentary databases, the models generalize well across chemistries. A key component of this work is a systematic analysis of the effect of different realistic experimental non-idealities on model performance. It is found that the addition of impurity phases, baseline noise and peak broadening present the greatest challenges to learning, while zero-offset error and random intensity modulations have little effect. However, appropriate data modification schemes can be used to bolster model performance and yield reasonable predictions, even for data which simulate realistic experimental non-idealities. In order to obtain accurate results, a new approach is introduced which uses the initial machine learning estimates with existing iterative whole-pattern refinement schemes to tackle automated unit-cell solution.

scholarly journals Change in lattice parameter of tantalum due to dissolved hydrogen

2012 ◽  
Vol 6 (2) ◽  
pp. 73-76 ◽  
Author(s):  
Manju Taxak ◽  
Sanjay Kumar ◽  
Nagaiyar Krishnamurthy ◽  
Ashok Suri ◽  
Gyanendra Tiwari
Keyword(s):  
Hydrogen Concentration ◽  
Constant Pressure ◽  
Solubility Limit ◽  
Lattice Parameter ◽  
Lattice Parameters ◽  
X Ray Diffraction ◽  
Solid Solubility Limit ◽  
X Ray ◽  
Peak Broadening ◽  
Dissolved Hydrogen

The volume expansion of tantalum due to the dissolved hydrogen has been determined using Bragg equation. The hydrogen was dissolved in the pure tantalum metal at constant temperature (360?C) and constant pressure (132 mbar) by varying the duration of hydrogen charging. The amount of dissolved hydrogen was within the solid solubility limit. The samples with different hydrogen concentration were analyzed by X-ray diffraction technique. Slight peak shifts as well as peak broadening were observed. The relative changes of lattice parameters plotted against the hydrogen concentration revealed that the lattice parameters varied linearly with the hydrogen concentration.

Structural Properties of InAs/AlSb Superlattices

1995 ◽  
Vol 379 ◽  
Author(s):  
B. Jenichen ◽  
H. Neuroth ◽  
B. Brar ◽  
H. Kroemer
Keyword(s):  
Buffer Layer ◽  
Peak Shift ◽  
Lattice Parameter ◽  
Structural Quality ◽  
Inhomogeneous Deformation ◽  
X Ray ◽  
Peak Broadening ◽  
Short Period ◽  
Intensity Ratios ◽  
Highly Correlated

ABSTRACTShort-period (InAs)6/(AlSb)6 superlattices (SL) with AlAs-like and InSb-like interfaces (IF) grown on a relaxed AlSb buffer layer are studied by X-ray reflectivity and diffractometry measurements. Reflectivity measurements reveal average IF roughnesses between 0.6 and 1.0 nm. Measurements of the diffuse scattering show that the roughness is highly correlated from layer to layer. Triple crystal area scans illustrate that the inhomogeneous deformation of the buffer layer leads to a certain symmetric peak broadening. In the case of AlAs-like IFs an additional broadening of the SL peaks reveals lattice parameter gradients over the superlattice. This asymmetric peak broadening may be attributed to a further relaxation of the superlattice, which is inhomogeneous with depth. The diffusion of As into the AlSb layers leads to a peak shift and modifies the intensity ratios of the different satellite reflections. The best structural quality is achieved for superlattices with InSb-like IFs.

Layer stacking disorder in Mg-Fe chlorites based on powder X-ray diffraction data

2020 ◽  
Vol 105 (3) ◽  
pp. 353-362
Author(s):  
Katarzyna Luberda-Durnaś ◽  
Marek Szczerba ◽  
Małgorzata Lempart ◽  
Zuzanna Ciesielska ◽  
Arkadiusz Derkowski
Keyword(s):  
Accurate Determination ◽  
Unit Cell ◽  
Powder Xrd ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
Xrd Pattern ◽  
X Ray ◽  
Cell Parameters ◽  
Layer Stacking

Abstract The primary aim of this study was the accurate determination of unit-cell parameters and description of disorder in chlorites with semi-random stacking using common X-ray diffraction (XRD) data for bulk powder samples. In the case of ordered chlorite structures, comprehensive crystallographic information can be obtained based on powder XRD data. Problems arise for samples with semi-random stacking, where due to strong broadening of hkl peaks with k ≠ 3n, the determination of unit-cell parameters is demanding. In this study a complete set of information about the stacking sequences in chlorite structures was determined based on XRD pattern simulation, which included determining a fraction of layers shifted by ±1/3b, interstratification with different polytypes and 2:1 layer rotations. A carefully selected series of pure Mg-Fe tri-trioctahedral chlorites with iron content in the range from 0.1 to 3.9 atoms per half formula unit cell was used in the study. In addition, powder XRD patterns were carefully investigated for the broadening of the odd-number basal reflections to determine interstratification of 14 and 7 Å layers. These type of interstratifications were finally not found in any of the samples. This result was also confirmed by the XRD pattern simulations, assuming interstratification with R0 ordering. Based on h0l XRD reflections, all the studied chlorites were found to be the IIbb polytype with a monoclinic-shaped unit cell (β ≈ 97°). For three samples, the hkl reflections with k ≠ 3n were partially resolvable; therefore, a conventional indexing procedure was applied. Two of the chlorites were found to have a monoclinic cell (with α, γ = 90°). Nevertheless, among all the samples, the more general triclinic (pseudomonoclinic) crystal system with symmetry C1 was assumed, to calculate unit-cell parameters using Le Bail fitting. A detailed study of semi-random stacking sequences shows that simple consideration of the proportion of IIb-2 and IIb-4/6 polytypes, assuming equal content of IIb-4 and IIb-6, is not sufficient to fully model the stacking structure in chlorites. Several, more general, possible models were therefore considered. In the first approach, a parameter describing a shift into one of the ±1/3b directions (thus, the proportion of IIb-4 and IIb-6 polytypes) was refined. In the second approach, for samples with slightly distinguishable hkl reflections with k ≠ 3n, some kind of segregation of individual polytypes (IIb-2/4/6) was considered. In the third approach, a model with rotations of 2:1 layers about 0°, 120°, 240° was shown to have the lowest number of parameters to be optimized and therefore give the most reliable fits. In all of the studied samples, interstratification of different polytypes was revealed with the fraction of polytypes being different than IIbb ranging from 5 to 19%, as confirmed by fitting of h0l XRD reflections.

X-ray-diffraction data of Pb2(C2O4)(NO3)2·2H2O

1996 ◽  
Vol 11 (1) ◽  
pp. 7-8 ◽  
Author(s):  
Hee-Lack Choi ◽  
Nobuo Ishizawa ◽  
Naoya Enomoto ◽  
Zenbe-e Nakagawa
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Unit Cell ◽  
Powder Diffraction Data ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Crystal System

X-ray powder-diffraction data for Pb2(C2O4)(NO3)2·2H2O were obtained. The crystal system was determined to be monoclinic. The unit-cell parameters were refined to a=10.613(2) Å, b=7.947(2) Å, c=6.189(1) Å, and β=104.48(2)°.

Precision Lattice Parameter Determination at Liquid Helium Temperatures by Double-Scanning Diffractometry

1966 ◽  
Vol 10 ◽  
pp. 354-365 ◽  
Author(s):  
Hubert W. King ◽  
Carolyn M. Preece
Keyword(s):  
Liquid Helium ◽  
Lattice Parameter ◽  
Lattice Parameters ◽  
Parameter Determination ◽  
Double Scanning ◽  
Cryogenic Temperatures ◽  
Included Angle ◽  
X Ray ◽  
Standard Specimens ◽  
Alignment Errors

AbstractThe back-reflect ion double-scanning diffractometer method, by which lattice parameters can be measured with a reproducibility of one part in 150,000 has been applied at liquid helium temperatures. A cryostat attachment is described which enables diffraction profiles to be scanned on both sides of the primary X-ray beam up to 163°, 2θ. Alignment errors may, thus, be eliminated by measuring the included angle 4θ between respective Bragg reflections. The method is illustrated by measuring the lattice parameters of the I.U.Cr. standard specimens of silicon and tungsten at various cryogenic temperatures.

Boron Carbide B25C and B8C18 Synthesized Using Boric Acid-Glucose and Boric Acid-Active Carbon at Low Temperature without Coreductor Materials

2014 ◽  
Vol 896 ◽  
pp. 609-612 ◽  
Author(s):  
Mufirah Cahya Fajrah Toana ◽  
Bambang Soegijono
Keyword(s):  
Boron Carbide ◽  
Boric Acid ◽  
Diffraction Pattern ◽  
Active Carbon ◽  
Lattice Parameters ◽  
X Ray Diffraction ◽  
Absorption Bands ◽  
Space Group ◽  
X Ray ◽  
Crystal System

This study examines the formation of Boron carbide with a wide homogeneity range B8C18 and B25C, from boric acid-glucose and boric acid-active carbon as precursor materials. The samples was analysed by means of X-ray diffraction and Fourier Transform Infrared spectrometer. X-ray diffraction pattern was analysed by GSAS software. X ray diffraction pattern of B8C18 shows peaks at 27o, 39o, 45o, 65o and 79o, orthorhombic crystal system and lattice parameters a = 13.640 Ǻ, b = 7.8500 Ǻ and c = 12.910 Ǻ and space group P212121, whereas for B25C sample show peaks at 2θ angle 28o and 40o, tetragonal crystal system, and the lattice parameters a = b = 8.753 Ǻ and c = 5.093 Ǻ and space group P-4 2 m. FTIR results show that for B8C18 have absorption bands with B-C bond at 1196.5 cm-1, 0-H 3216.7 cm-1 and B-O at 1477.1 cm-1, whereas the formation B25C have absorption bands with B-C bond at 1195.1 cm-1, O-H 3216.7 cm-1 and B-O 1460.8 cm-1.

Characterization of microstructures in Inconel 625 using X-ray diffraction peak broadening and lattice parameter measurements

2004 ◽  
Vol 51 (1) ◽  
pp. 59-63 ◽  
Author(s):  
Sanjay K. Rai ◽  
Anish Kumar ◽  
Vani Shankar ◽  
T. Jayakumar ◽  
K. Bhanu Sankara Rao ◽  
...  
Keyword(s):  
Lattice Parameter ◽  
Diffraction Peak ◽  
Inconel 625 ◽  
X Ray Diffraction ◽  
X Ray ◽  
Peak Broadening

Kristall- und Molekülstruktur von 5.10-Dihydro-5.10-diniethylphenaziniiimtniodid und 5.10-Dihydro-5.10-diethylphenaziniumtriiodid / Molecular and Crystal Structure of 5,10-Dihydro-5.10-dimethylphenaziniumtriiodide and 5.10-Dihydro-5.10-diethylphenazinium triiodide

1978 ◽  
Vol 33 (8) ◽  
pp. 838-842 ◽  
Author(s):  
H. J. Keller ◽  
W. Moroni ◽  
D. Nöthe ◽  
M. Scherz ◽  
J. Weiss
Keyword(s):  
Crystal Structure ◽  
Radical Cations ◽  
Unit Cell ◽  
Lattice Parameters ◽  
Molecular And Crystal Structure ◽  
Reaction Conditions ◽  
Space Group ◽  
X Ray ◽  
R Value

Oxidation of 5,10-dihydro-5,10-dimethylphenazine and 5,10-dihydro-5,10-diethyl-phenazine under different reaction conditions leads to several iodine containing solids. The preparation and X-ray structure of two of them, 5,10-dihydro-5,10-dimethyl-phcnaziniumtriiodide (3) and 5,10-dihydro-5,10-diethylphenaziniumtriiodido (4) are reported here.Compound 3 crystallizes in space group P21/n with lattice parameters a = 8.552(6) Å, b= 16.953(2) Å, c- 12.157(9) Å and β= 103.46(2)° with four formula units in the unit cell. The structure was refined to an R-value of 0.046 using 2387 independent reflections. The lattice constains distinct, slightly distorted triiodide ions and bent 5,10-dihydro-5,10-dimethylphenazinium radical cations. Compound 4 crystallizes in the same space group P21/n with lattice parameters a = 8.531(6) Å, b = 8.332(21) Å, c = 13.320(15) Å and β= 94.44(19)° with two formula units in the unit cell. The structure was refined to an R-value of 0.076 using 1195 independent reflections. The lattice contains strictly linear symmetrical triiodide ions and planar centrosymmetrical 5,10-dihydro-5,10-diethyl- phenazinium radical cations.

scholarly journals Synthesis And Structural Characterization Of 1-Butyl-2,3-Dimethylimidazolium Bromide And Iodide

2007 ◽  
Vol 62 (6) ◽  
pp. 868-870 ◽  
Author(s):  
Johanna Kutuniva ◽  
Raija Oilunkaniemi ◽  
Risto S. Laitinen ◽  
Janne Asikkala ◽  
Johanna Kärkkäinen ◽  
...  
Keyword(s):  
Unit Cell ◽  
Monoclinic Crystal System ◽  
Monoclinic Crystal ◽  
Space Group ◽  
X Ray ◽  
Crystal System ◽  
H Nmr ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

1-Butyl-2,3-dimethylimidazolium bromide {(bdmim)Br} (1) and iodide {(bdmim)I} (2) were prepared conveniently by the reaction of 1,2-dimethylimidazole and the corresponding 1-halobutane. The compounds were characterized by 1H and 13C{1H} NMR spectroscopy as well as by X-ray single crystal crystallography. 1 crystallizes in the monoclinic crystal system, space group P21/n, with Z = 4, and unit cell dimensions a = 8.588(2), b = 11.789(1), c = 10.737(2) Å, β = 91.62(3)°. Compound 2 crystallizes in the monoclinic crystal system, space group P21/c, with Z = 8, and unit cell dimensions a = 10.821(2), b = 14.221(3), c = 15.079(2) Å , β = 90.01(3)°. The lattices of the salts are built up of 1-butyl-2,3- dimethylimidazolium cations and halide anions. The cations of 1 form a double layer with the imidazolium rings stacked together due to π interactions. The Br− anions lie approximately in the plane of the imidazolium ring, and the closest interionic Br···H contacts span a range of 2.733(1) - 2.903(1) Å. Compound 2 shows no π stacking interactions. The closest interionic I···H contacts are 2.914(1) - 3.196(1) Å

scholarly journals Structural Analysis of Platinum Nanoparticles on Carbon Nanotube Surface as Electrocatalyst System

2017 ◽  
Vol 9 (2) ◽  
pp. 60 ◽  
Author(s):  
Sudirman Sudirman ◽  
Indriyati Indriyati ◽  
Wisnu Ari Adi ◽  
Rike Yudianti ◽  
Emil Budianto
Keyword(s):  
Cell Volume ◽  
Unit Cell Volume ◽  
Average Particle Size ◽  
Unit Cell ◽  
Lattice Parameters ◽  
Atomic Density ◽  
Average Particle ◽  
X Ray Diffraction ◽  
Great Opportunity ◽  
X Ray

Synthesis of Pt/CNT composite by using sol gel method has been performed which the composition of CNT on the composite are vary, (x = 20, 40, 60 and 80 wt%). Performance of composite was characterized by Transmission Electron Microscope (TEM) and X-Ray Diffraction (XRD), respectively. In the refinement results of X-ray diffraction pattern, the composite consists of two phases, namely, carbon and platinum phases. Carbon phase has a structure hexagonal (P 63 m c) with lattice parameters a = b = 2.451(2) Å and c = 6.89(1) Å, α = β = 90° and γ = 120°, the unit cell volume of V = 35.8(1) A3, and the atomic density of ρ = 2.224 g.cm-3. While platinum phase has the structure of cubic (F m -3 m) with lattice parameters a = b = c = 3.921(2) Å, α = β = γ = 90°, the unit cell volume of V = 60.3(1) A3, and the atomic density of ρ = 21.487 g.cm-3.According to the image of TEM, the average particle size for Pt nano particle is estimated to range from 4.1-4.3 nm. While the cavity diameter average of CNT is estimated to range from 5.9-7.5 nm. Based on the calculation, the crystallite size of the Pt particle was around 4.31 nm. The optimum value of dispersed Pt into CNT occurred at 60 wt% CNT with the best composition of Pt in the unit cell of cystal structure. We concluded that this study successfully dispersed Pt nanoparticles onto CNT formed Pt/CNT composite. This was a great opportunity that the composite can be applied as electrocatalyst system on fuel cell application.

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