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.

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

Thermodynamic Analysis of the Extension of Solid Solubility of the Cu-Cr System Processed by Mechanical Alloying

2011 ◽  
Vol 311-313 ◽  
pp. 392-395 ◽  
Author(s):  
Kun Yu Shi ◽  
Tao Shen ◽  
Li Hong Xue ◽  
Chun Hao Chen ◽  
You Wei Yan
Keyword(s):  
Mechanical Alloying ◽  
Thermodynamic Analysis ◽  
Solid Solubility ◽  
Structural Changes ◽  
Milling Time ◽  
Solubility Limit ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cr System

The nanocrystalline Cu-5wt.%Cr alloy powders were prepared by mechanical alloying. The structural changes were characterized by X-ray diffraction (XRD) technique. A thermodynamic analysis was carried out to predict the change in the solubility limit of this system. It was found that the energy resulting from the MA process is sufficient to increase the solid solubility of immiscible Cr-Cu system. The solid solubility may be extended up to 5 wt.% Cr in Cu after 20 h milling. The formation of the supersaturated solid solution leads to the decrease of Cu lattice parameter. However, it decomposes with the further increase of the milling time, which leads to the increase of Cu lattice parameter.

Characterization of the Aurivillius Type PbBi4Ti4O15 Piezoelectric Ceramic Doped with Eu3+

2006 ◽  
Vol 45 ◽  
pp. 2483-2488
Author(s):  
L. Pablos ◽  
Maria Elena Villafuerte-Castrejón ◽  
A. Ibarra-Palos ◽  
J. Ocotlán-Flores ◽  
R. Sato ◽  
...  
Keyword(s):  
Piezoelectric Ceramic ◽  
Solubility Limit ◽  
Lattice Parameter ◽  
Layered Oxides ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Density Measurements ◽  
X Ray ◽  
Wide Range

PbBi4Ti4O15 belongs to the bismuth oxide layers family discovered by Aurivillius more than 50 years ago. In the last few years, there has been considerable interest in layered oxides exhibiting ferroelectric, piezoelectric and other related properties due to their wide range of application in technical devices. In the present work the PbBi4Ti4O15 solid solution formed with Eu3+ was synthesized by coprecipitation method and solubility limit was found. All compounds were characterized by scanning electron microscopy, density measurements and X-ray diffraction. The variation of lattice parameter with the Eu3+ concentration was obtained. Raman spectroscopy was carried out in order to determine the Eu3+ site in the lattice. Thermal analysis (thermogravimetry and differencial scanning calorimetry) results are also presented.

Lattice parameters and spontaneous strain in AX 2 polytypes: CdI2, PbI2 SnS2 and SnSe2

1989 ◽  
Vol 22 (6) ◽  
pp. 622-623 ◽  
Author(s):  
B. Pałosz ◽  
E. Salje
Keyword(s):  
Diffraction Pattern ◽  
Powder Diffraction ◽  
Basal Plane ◽  
Lattice Parameter ◽  
Structural Transformations ◽  
Lattice Parameters ◽  
The Other ◽  
X Ray Diffraction ◽  
Spontaneous Strain ◽  
X Ray

Structural transformations between polytypes of a given material are expected to lead to lattice relaxations. Powder X-ray diffraction of basic AX 2 polytypes of CdI2, PbI2, SnS2 and SnSe2 showed these relaxations for the repetition unit along the stacking axis, conventionally the c axis. No variation of the lattice parameters were detected in the basal plane (001), except for CdI2 where small variations occur also for the a lattice parameter. The tensor of the spontaneous strain has its maximum component e 3 ≲ 12 × 10−4 for SnS2. The powder diffraction pattern and lattice parameters of the phases of CdI2 (2H, 12R, 4H), PbI2 (2H, 12R), SnS2 (2H, 18R, 4H) and SnSe2 (2H, 18R) are given. JCPDS Diffraction File Nos. are: 40-1468 for CdI2-12H; 40–1469 for CdI2-2H; 40-1466 for SnS2-18R, 40–1467 for SnS2-2H; 40–1465 for SnSe2-18R. The other polytypes studied in this paper have data in earlier sets of the PDF.

X-ray powder diffraction and magnetic study of nominal Zn1-xNdxCr2Se4 – compounds (x = 0.05, 01)

2013 ◽  
Vol 28 (S2) ◽  
pp. S75-S85
Author(s):  
Izabela Jendrzejewska ◽  
Paweł Zajdel ◽  
Ewa Maciążek ◽  
Maria Sozańska ◽  
Tomasz Goryczka
Keyword(s):  
Chemical Composition ◽  
Solid State ◽  
Powder Diffraction ◽  
Magnetic Moments ◽  
Solubility Limit ◽  
Lattice Parameter ◽  
Antiferromagnetic Coupling ◽  
X Ray Diffraction ◽  
X Ray ◽  
Pure Matrix

Polycrystalline compounds in the Zn1-xNdxCr2Se4 system were prepared by solid state reaction using selenides (ZnSe, Cr2Se3) and pure elements (Nd, Se) as starting materials. The structural properties were determined by X-ray diffraction and the chemical composition confirmed by SEM-EDX. The observed symmetry is cubic, space group Fd3m, while the lattice parameter varies from 10.4955(7)Å to 10.4976(7)Å, and is larger than for the pure matrix. The solubility limit for the current synthesis route lies below x = 0.1. The magnetic moments, effective and saturation, increase with increasing amount of Nd ions. The Neel temperature TN and ΘCW drop, respectively, to 17.4K and 81K for x = 0.1, independently indicating that neodymium is incorporated into the spinel lattice and promotes antiferromagnetic coupling between the Cr3+ ions.

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.

Lineshape Analysis of X-ray Diffraction Profiles: Polyethylene and Model Copolymers

1990 ◽  
Vol 34 ◽  
pp. 519-529
Author(s):  
Buckley Crist ◽  
Paul R. Howard
Keyword(s):  
Crystal Size ◽  
Lattice Parameter ◽  
Parameter Fluctuation ◽  
Line Profiles ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lineshape Analysis ◽  
Small Peak ◽  
Peak Broadening ◽  
Diffraction Peaks

Studies of the shapes of X-ray diffraction peaks from synthetic polymers are still rather uncommon. One probable cause of this situation is the small peak-to-background ratio in most polymer diffraction experiments; it is difficult to achieve precise line profiles for quantitative analysis. Increased utilization of automated data collection/analysis systems and more intense X-ray sources should alleviate this restriction. We suspect, furthermore, that confusion about nomenclature has impeded the acceptance of lineshape analysis for polymers. The peak broadening mechanisms which are generally considered are finite coherence length or crystal size, lattice parameter fluctuation, and displacement disorder of the second kind. Both latter mechanisms have, unfortunately, been referred to as “strains” or “microstrains”. Metallurgists have traditionally expressed displacement disorder as a (length dependent) “microstrain”, and this convention has been adopted in some studies of polymer diffraction. Other work on polymers, however, has termed lattice parameter fluctuation as “microstrain“. The inconsistent use of this term can imply a nonexistent relation between two distinct phenomena.

A Comparison of X-Ray and Neutron Diffraction Measurement of Lattice Parameters for the Determination of Residual Stress and Chemical Composition in Zirconium Alloy Tubes

1991 ◽  
Vol 35 (A) ◽  
pp. 475-480
Author(s):  
M. Griffiths ◽  
J.E. Winegar ◽  
J.F. Mecke ◽  
T.M. Holden ◽  
R.A. Holt
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
Zirconium Alloys ◽  
Lattice Parameter ◽  
Lattice Parameters ◽  
Surface Relaxation ◽  
Chemical Compositions ◽  
X Ray Diffraction ◽  
X Ray

AbstractIntergranular residual stresses can exist in zirconium alloys, especially when there is a large distribution of grain orientations. The stresses result from the anisotropic plasticity and thermal expansion of the hexagonal close-packed crystal structure of α-zirconium. Apart from complicating the characterisation of materials using lattice parameter measurements, the intergranular stresses can significantly affect material behaviour, especially in nuclear reactor environments, and there is therefore a great deal of interest in their measurement.The effects of specimen preparation and surface relaxation on X-ray diffraction measurements of lattice parameters of zirconium alloys have been investigated by comparing bulk neutron diffraction with X-ray diffraction on identical materials. The results show that: (i) intergranular or interphase residual stresses exist in dual-phase Zr-2.5Nb pressure tubes; (ii) the stresses normal to the surface of an X-ray diffraction specimen are not relieved completely when there are intergranular residual stresses in the material. One can conclude that intergranular stresses have to be considered when determining chemical compositions from lattice parameter measurements and also when measuring macroscopic residual stress using X-ray diffraction.

Substrate Strain Measurements in Mbe Grown Silicon on Sapphire

1988 ◽  
Vol 116 ◽  
Author(s):  
Joseph Pellegrino ◽  
Syed Qadri ◽  
Eliezer Richmond ◽  
Mark Twigg ◽  
Carl Vold
Keyword(s):  
Critical Thickness ◽  
Growth Parameters ◽  
Bragg Reflection ◽  
Silicon Film ◽  
Lattice Parameter ◽  
Bulk Silicon ◽  
X Ray Diffraction ◽  
X Ray ◽  
Peak Broadening ◽  
Reflection Peak

AbstractAn x-ray diffraction study is made of the effect of silicon film thickness on the peak broadening associated with the (024) sapphire Bragg reflection peak for MBE—grown SOS material. The predeposition treatment and growth parameters for the samples in the series were identical. The thicknesses ranged from 5500 to 40,000 angstroms and the growth rate was roughly I angstrom/second.SOS films with silicon thicknesses below 5500A did not produce sapphire peak broadening when compared with the corresponding sapphire standard. With reference to standard sapphire reflection peaks, the 5500A film shows slight broadening while a I micron film broadened 14 seconds of arc when compared at FWHM with the sapphire standard. A possible explanation for this is that at overlayers less than 5500A, the film is not sufficiently massive to exert a uniform strain on the sapphire. At 5500A the film attains a critical thickness sufficient to strain the substrate and produce detectable broadening. For thickerfilms the strain would increase proportionally. Results from lattice parameter measurements on the silicon epilayer indicate that the perpendicular lattice parameter relaxes atgreater thicknesses but is still in tension when compared with bulk silicon. One would expect that the strain gradient suggested by these results would be greatest at the silicon/sapphire interface and that the defect concentration at the interface might beaffected by this strained condition.

Incorporation of Pb into the Crystal Structure of Ba6−3xNd8+2xTi18O54 Solid Solution

2000 ◽  
Vol 15 (8) ◽  
pp. 1735-1741 ◽  
Author(s):  
Mojca Podlipnik ◽  
Danilo Suvorov ◽  
Matjaz Valant ◽  
Drago Kolar
Keyword(s):  
Crystal Structure ◽  
Solid Solubility ◽  
Microwave Dielectric Properties ◽  
Solubility Limit ◽  
Nominal Composition ◽  
Secondary Phases ◽  
Q Value ◽  
X Ray Diffraction ◽  
Solid Solubility Limit ◽  
X Ray

Investigations of a substitutional mechanism of Pb incorporation into the crystal structure of Ba6−3xNd8+2xTi18O54 performed by x-ray diffraction analysis, scanning electron microscopy, and energy dispersive and wavelength dispersive x-ray spectroscopy revealed that Pb2+ substitutes for Ba2+ according to the formula (Ba1−zPbz)6−3xNd8+2xTi18O54. The solid solubility limit for 0.5 = x = 0.6 compositions was determined to be at 0.35 ≤ z < 0.4 (nominal composition) which, according to measurements of PbO loss occurring during the heat treatment, gives 0.30 ≤ z < 0.35 (analyses of matrix phase). Increasing the Pb2+ concentration in (Ba1−zPbz)4.5Nd9Ti18O54, results in tf decreasing from an initial positive value (80 ppm/K) to a negative value at the solid solubility limit (−25 ppm/K at z = 0.35). In the same concentration range the Q-value decreases from an initial 2000 to 1250 (z. = 0.35), measured at 4 GHz, while permittivity remains almost constant (k = 87 ± 1.5). After exceeding the solid solubility limit of Pb2+ in (Ba1−zPbz)4.5Nd9Ti18O54 the appearance of secondary phases (Nd4Ti9O24 and Pb-rich phase at grain boundaries) changes the trends of the microwave dielectric properties; permittivity decreases, Q-value remains almost constant, and Tf increases.

Sign in / Sign up

Export Citation Format

Share Document