scholarly journals X-Ray Line Broadening and Pure Diffraction Contours

1954 ◽  
Vol 7 (1) ◽  
pp. 77 ◽  
Author(s):  
RI Garrod ◽  
JF Brett ◽  
JA MacDonald
Keyword(s):  
Particle Size ◽  
Fourier Series ◽  
Polycrystalline Materials ◽  
Line Profiles ◽  
Line Broadening ◽  
X Ray ◽  
Experimental Line

In analysing the data from experiments designed to distinguish between particle size and distortion broadening from polycrystalline materials, it is customary either to employ correction formulae to obtain the true broadening �, or to derive the pure diffraction contour in terms of a Fourier series whose coefficients may be evaluated from the experimental line profiles.

Analytical formulation of the variance method of line-broadening analysis for Voigtian X-ray diffraction peaks

2006 ◽  
Vol 39 (4) ◽  
pp. 598-600 ◽  
Author(s):  
Florentino Sánchez-Bajo ◽  
Angel L. Ortiz ◽  
Francisco L. Cumbrera
Keyword(s):  
Square Lattice ◽  
Polycrystalline Materials ◽  
Alternative Formulation ◽  
Line Profiles ◽  
Line Broadening ◽  
X Ray Diffraction ◽  
X Ray ◽  
Variance Method ◽  
Instrumental Line ◽  
Diffraction Peaks

An alternative formulation of the variance method for the line-broadening analysis of polycrystalline materials is presented. It maintains the theoretical basis of the earlier formulations of the variance method, but differs in the manner of calculating the variance coefficients of the line profiles. In the proposed formulation, these are evaluated analytically in terms of the shape parameters of Voigt functions fitted to the X-ray diffraction data. Explicit expressions are thus derived for calculating the (surface-weighted) crystal sizes and (root-mean-square) lattice microstrains from the integral breadths of the Gauss and Lorentz components of the Voigt functions that model the experimental and instrumental line profiles.

Flat Crystal X-Ray Optics

1957 ◽  
Vol 1 ◽  
pp. 193-206 ◽  
Author(s):  
William J. Campbell ◽  
Melvin Leon ◽  
John Thatcher
Keyword(s):  
Wave Length ◽  
Pulse Height ◽  
Line Profiles ◽  
Line Broadening ◽  
Crystal Surfaces ◽  
X Ray ◽  
Line Intensities ◽  
Long Wave ◽  
On Line ◽  
College Park

AbstractAn investigation was undertaken by the Bureau of Mines at College Park, Md., to determine the effect of various combinations of collimators, analyzing crystals and detectors on line intensities, line-to-backgrouhd ratios, and spectral resolution. The research showed that line broadening due to mosaic crystal surfaces was greatly reduced and line splitting from faults was eliminatedby the use of two fine collimators (0.005 inch, spacing, 4 inch length). Line intensities were reduced, but lineto- background ratios arid line profiles were substantially improved with double collimators. Pulse height discrimination resulted in marked improvement in the line-to-background ratio in the long-wave length region, 2 to 10 A, but was much less effective for shorter wave lengths.

scholarly journals The interpretation of protoplanetary disc wind diagnostic lines from X-ray photoevaporation and analytical MHD models

2020 ◽  
Vol 496 (1) ◽  
pp. 223-244 ◽  
Author(s):  
Michael L Weber ◽  
Barbara Ercolano ◽  
Giovanni Picogna ◽  
Lee Hartmann ◽  
Peter J Rodenkirch
Keyword(s):  
Trace Gas ◽  
Line Profiles ◽  
Line Broadening ◽  
Low Velocity ◽  
X Ray ◽  
Double Peaks ◽  
Multiple Components ◽  
Spectral Profiles ◽  
Extended Mhd ◽  
Gaussian Decomposition

ABSTRACT High-resolution spectra of typical wind diagnostics ([O i] 6300 Å and other forbidden emission lines) can often be decomposed into multiple components: high-velocity components with blueshifts up to several 100 km s−1 are usually attributed to fast jets, while narrow (NLVC) and broad (BLVC) low-velocity components are believed to trace slower disc winds. Under the assumption that the line broadening is dominated by Keplerian rotation, several studies have found that the BLVCs should trace gas launched between 0.05 and 0.5 au and correlations between the properties of BLVCs and NLVCs have been interpreted as evidence for the emission tracing an extended magnetohydrodynamics (MHD) wind and not a photoevaporative wind. We calculated synthetic line profiles obtained from detailed photoionization calculations of an X-ray photoevaporation model and a simple MHD wind model and analysed the emission regions of different diagnostic lines and the resulting spectral profiles. The photoevaporation model reproduces most of the observed NLVCs but not the BLVCs or HVCs. The MHD model is able to reproduce all components but produces Keplerian double peaks at average inclinations that are rarely observed. The combination of MHD and photoevaporative winds could solve this problem. Our results suggest that the Gaussian decomposition does not allow for a clear distinction of flux from different wind regions and that the line broadening is often dominated by the velocity gradient in the outflow rather than by Keplerian rotation. We show that observed correlations between BLVC and NLVC do not necessarily imply a common origin in an extended MHD wind.

Strain and Particle Size of Palladium Metal Powders by Time-of-Flight Neutron Diffraction

1989 ◽  
Vol 33 ◽  
pp. 403-407
Author(s):  
A. C. Lawson ◽  
J. W. Conant ◽  
C. L. Talcott ◽  
M. A. David ◽  
J. Vaninetti ◽  
...  
Keyword(s):  
Particle Size ◽  
Neutron Diffraction ◽  
Powder Diffraction ◽  
Time Of Flight ◽  
Metal Powders ◽  
Line Broadening ◽  
X Ray ◽  
Palladium Powder ◽  
Time Of Flight Method ◽  
Palladium Metal

AbstractWe have determined the strain and particle size for several samples of palladium powder by time-of-flight nrutron powder diffraction on two different diffractometers and by x-ray powder diffraction. The results are compared and found to be in fair agreement. The time-of-flight method gives good enough precision to reveal deficiencies in the simple models used for strain and particle size line broadening.

X-Ray Profile Analysis of 12% Chromium Stainless Steel

1993 ◽  
Vol 37 ◽  
pp. 351-358
Author(s):  
Zenjxo Yajima ◽  
Ken-ichi Ishikawa ◽  
Toshihiko Sasaki ◽  
Yukio Hirose
Keyword(s):  
Particle Size ◽  
Structural Changes ◽  
Lattice Strain ◽  
Profile Analysis ◽  
Good Method ◽  
Small Particle Size ◽  
Line Broadening ◽  
X Ray ◽  
Diffraction Peaks ◽  
Chromium Stainless Steel

X-ray line broadening is caused by variations in lattice strain and small particle size. When hydrogen is introduced into the steel by the electrolytica! method, structural changes are observed. X-ray line broadening is a suitable measurement in such cases. The Warren and Averbach Fourier analysis is a good method for line broadening studies. In this method, strain and particle size effects can be separated because broadening due to particle size is independent of order of the diffraction peaks, while broadening due to strain is not.

Evaluation of Straight and Curved Braun Position-Sensitive Proportional Counters on a Huber-Guinier X-Ray Diffraction System

1983 ◽  
Vol 27 ◽  
pp. 261-266 ◽  
Author(s):  
R.A. Newman ◽  
P. Moore Kirchhoff ◽  
T.G. Fawcett
Keyword(s):  
Scintillation Counter ◽  
Line Profiles ◽  
Line Broadening ◽  
X Ray Diffraction ◽  
Camera System ◽  
X Ray ◽  
Proportional Counters ◽  
On Line ◽  
Position Sensitive ◽  
Gas Chamber

AbstractThe interfacing of both straight and curved Braun Position- Sensitive Proportional Counters (PSPC's) to a high resolution Huber-Guinier camera system has been accomplished, resulting in a 10 to 100-fold decrease in data collection times when compared to conventional Guinier (film or scintillation counter) detector techniques.Various factors causing line broadening were evaluated for both PSPC Guinier systems. The depth of the PSPC gas chamber was found to Have the greatest influence on line profiles. An R0% increase in peak half-widths was observed for PSPC-Guinier data compared to our highest resolution Guinier film data, but still yielded significantly better resolution than conventional powder diffractometer data obtained in our laboratory.

ENHANCED MAGNETIZATION IN COBALT SUBSTITUTED Ni–Zn NANOFERRITES

2011 ◽  
Vol 10 (04n05) ◽  
pp. 571-576 ◽  
Author(s):  
M. CHAITANYA VARMA ◽  
A. MAHESH KUMAR ◽  
K. H. RAO
Keyword(s):  
Particle Size ◽  
Room Temperature ◽  
Sol Gel ◽  
Chelating Agent ◽  
Lattice Parameter ◽  
Line Broadening ◽  
X Ray Diffraction ◽  
Chemical Methods ◽  
X Ray ◽  
Nickel Zinc

Cobalt substituted nickel zinc ferrite nanoparticles ( Ni 0.65–x Co x Zn 0.35 Fe 2.0 O 4) X varying from 0.0 to 0.65 in steps of 0.15 have been produced using sol–gel method, with PVA as chelating agent. The phase formation of the sintered ferrite was confirmed by X-ray diffraction studies. The lattice parameter a(A°) has been calculated using Nelson–Riley method. The crystallite size has been estimated by the Williamson–Hall method using the full width at half-maximum (FWHM) of the line broadening of all the peaks. Mössbauer spectroscopy (MS) of the samples showed the clear presence of two sextets and distribution of iron over the two sites has been given. Increase in saturation magnetization with cobalt concentration with a slight decrease for x = 0.15 has been observed with the vibrating sample magnetometry study. The observed value of magnetization for Ni0.65Zn0.35Fe2O4 with a particle size of 43.5 nm has been 71 emu/gm at room temperature, which is higher than that reported for samples prepared using chemical methods of the same composition. The results have been explained on the basis of the particle size and cation distribution among various sites.

X-Ray Line Profile Analysis for Single Crystals

2014 ◽  
pp. 242-270
Keyword(s):  
Single Crystals ◽  
Intensity Distribution ◽  
Profile Analysis ◽  
Reciprocal Lattice ◽  
Lattice Points ◽  
Polycrystalline Materials ◽  
Line Profile Analysis ◽  
Line Profiles ◽  
X Ray ◽  
Lattice Misorientation

The features of the dislocation structure in plastically deformed single crystals can be determined from diffraction line broadening. Both the measuring and the evaluation procedures of X-ray line profiles are somewhat different from the methods used for polycrystalline materials. In this chapter, these procedures are overviewed, and their effectiveness is illustrated by representative examples. It is shown that the intensity distribution in the vicinity of the reciprocal lattice points can be mapped by rocking the single crystal about appropriate axes. From the detected intensity distribution, the density, the slip systems, and the arrangement of dislocations, as well as the lattice misorientation can be determined. The average misorientation obtained from rocking curve measurement can be related to the density of geometrically necessary dislocations. It is also shown that the inhomogeneous distribution of dislocations in plastically deformed single crystals usually results in asymmetric line profiles. The evaluation of these peaks enables the determination of the long-range internal stresses besides the dislocation densities in the dislocation cell walls and interiors.

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