QUANTITATIVE MANOMETRIC DETERMINATION OF CALCITE AND DOLOMITE IN SOILS AND LIMESTONES

1959 ◽  
Vol 39 (2) ◽  
pp. 197-204 ◽  
Author(s):  
S. I. M. Skinner ◽  
R. L. Halstead ◽  
J. E. Brydon
Keyword(s):  
Complete Solution ◽  
X Ray Diffraction ◽  
Linear Portion ◽  
X Ray ◽  
The Difference ◽  
Time Extrapolation ◽  
Zero Time ◽  
Manometric Determination ◽  
Good Agreement

The determination is based on the difference in rates of solution of calcite and dolomite. The CO2 evolved from reaction of a mixture of calcite and dolomite in excess HCl is measured at frequent intervals until the reaction is completed. The logarithm of the amount of CO2 equivalent to unreacted carbonate is plotted against time. Following the rapid and complete solution of calcite, the curve for dolomite assumes a much smaller slope and is linear for a period of time. Extrapolation of this linear portion of the curve to zero time gives the amount of CO2 equivalent to the dolomite initially present. The CO2 from calcite is obtained by difference from the total CO2. The amounts of calcite and dolomite found in a number of prepared mixtures by this intercept method were in good agreement with the amounts known to be present. Several samples of limestone and calcareous soil were analysed by the proposed method and the results were compared with X-ray diffraction and chemical data.

Local atomic structure in tetragonal pure ZrO2nanopowders

2010 ◽  
Vol 43 (2) ◽  
pp. 227-236 ◽  
Author(s):  
Leandro M. Acuña ◽  
Diego G. Lamas ◽  
Rodolfo O. Fuentes ◽  
Ismael O. Fábregas ◽  
Márcia C. A. Fantini ◽  
...  
Keyword(s):  
Tetragonal Phase ◽  
Local Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Atomic Structures ◽  
Crystallite Sizes ◽  
Exafs Study ◽  
The Difference ◽  
X Ray Absorption ◽  
Good Agreement

The local atomic structures around the Zr atom of pure (undoped) ZrO2nanopowders with different average crystallite sizes, ranging from 7 to 40 nm, have been investigated. The nanopowders were synthesized by different wet-chemical routes, but all exhibit the high-temperature tetragonal phase stabilized at room temperature, as established by synchrotron radiation X-ray diffraction. The extended X-ray absorption fine structure (EXAFS) technique was applied to analyze the local structure around the Zr atoms. Several authors have studied this system using the EXAFS technique without obtaining a good agreement between crystallographic and EXAFS data. In this work, it is shown that the local structure of ZrO2nanopowders can be described by a model consisting of two oxygen subshells (4 + 4 atoms) with different Zr—O distances, in agreement with those independently determined by X-ray diffraction. However, the EXAFS study shows that the second oxygen subshell exhibits a Debye–Waller (DW) parameter much higher than that of the first oxygen subshell, a result that cannot be explained by the crystallographic model accepted for the tetragonal phase of zirconia-based materials. However, as proposed by other authors, the difference in the DW parameters between the two oxygen subshells around the Zr atoms can be explained by the existence of oxygen displacements perpendicular to thezdirection; these mainly affect the second oxygen subshell because of the directional character of the EXAFS DW parameter, in contradiction to the crystallographic value. It is also established that this model is similar to another model having three oxygen subshells, with a 4 + 2 + 2 distribution of atoms, with only one DW parameter for all oxygen subshells. Both models are in good agreement with the crystal structure determined by X-ray diffraction experiments.

Phase analysis of sintered yttria–zirconia ceramics by x-ray diffraction

1986 ◽  
Vol 1 (2) ◽  
pp. 295-299 ◽  
Author(s):  
A. Paterson ◽  
R. Stevens
Keyword(s):  
Tetragonal Phase ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Zirconia Ceramics ◽  
X Ray ◽  
Different Temperatures ◽  
Shear Transformation ◽  
Original Amount ◽  
Good Agreement

Determination of the amount of cubic and tetragonal phase in yttria–zirconia using high-angle XRD (x-ray diffraction) has been complicated by problems of resolution and interpretation. The evidence, from electron diffraction studies, for a c→t shear transformation also needs to be taken into account. Two compositions, a 3 and a 5.7 mol % Y2O3−ZrO2, were sintered and thermally treated at different temperatures between 1450°and 1700°C. X-ray diffraction traces revealed the anticipated tetragonal (400) and (004) reflections. The region of the diffraction pattern that was thought to arise from the cubic phase could be best interpreted as a second tetragonal phase t'. The original amount of cubic phase computed from the t' reflections showed good agreement with the phase diagram of Scott. The lattice parameters of the t' phase were determined, and the volume of the tetragonal (t') unit cell was calculated.

scholarly journals X-Ray Diffraction and Density Distribution Measurements on the Al2O3 Crystals Grown by Czochralski Method with Different Pull Rate

2015 ◽  
Vol 1 (1) ◽  
pp. 1 ◽  
Author(s):  
Hamdan Hadi Kusuma
Keyword(s):  
Density Measurement ◽  
Czochralski Method ◽  
X Ray Diffraction ◽  
Powder Diffraction File ◽  
Hexagonal System ◽  
X Ray ◽  
Lattice Constants ◽  
The Difference ◽  
Measurement Base ◽  
Good Agreement

The Al<sub>2</sub>O<sub>3</sub> crystal has been done by Czochralki Method with different pull rate. The effect of pull rate on the Al<sub>2</sub>O<sub>3</sub> single crystal was characterized using X-ray diffraction and density measurement. Base on the XRD result of Al<sub>2</sub>O<sub>3</sub> crystal, which belongs to the hexagonal system, except for the difference in the relative intensity, present diffraction data which are found to be in good agreement with those of the powder diffraction file (PDF) 43-1484 provided by the JCPDS. It was observed the structure with symmetry group <em>D</em><sup>6</sup><sub>3d</sub>–<em>R</em>3<em>C </em>and has lattice constants being <em>a </em>= 4.759 Å, <em>c</em> = 12.99 Å. The density of the crystals increased with the pull rate. This phenomenon is caused by the speed of the pull rate crystal that causes changes in the heat flow in the furnace and then changed homogeneities of species distribution of atoms along the crystal. © 2015 JNSMR UIN Walisongo. All rights reserved.

Bismuth on GaSb(110): Structural Determination of the 1×1 and 1×2 Phases by Surface X-Ray Diffraction

1998 ◽  
Vol 05 (05) ◽  
pp. 1043-1052 ◽  
Author(s):  
L. Lottermoser ◽  
T. Van Gemmeren ◽  
O. Bunk ◽  
R. L. Johnson ◽  
E. Landemark ◽  
...  
Keyword(s):  
Structural Model ◽  
Layer Structure ◽  
Zigzag Chain ◽  
X Ray Diffraction ◽  
Surface Geometry ◽  
X Ray ◽  
Reconstructed Surface ◽  
Thermal Stability Of ◽  
Good Agreement

The surface geometry of the 1×1 and 1×2 phases of bismuth on GaSb(110) has been determined using surface X-ray diffraction with synchrotron radiation. The bismuth atoms form zigzag chains along the [Formula: see text] direction of the substrate. For the 1×1 phase four different registries of the bismuth chains with respect to the GaSb(110) substrate are possible. It was found that only the epitaxial continued layer structure was in good agreement with the experimental data. In the 1×2 reconstruction every second zigzag chain in the uppermost substrate layer is missing. The reconstructed surface is terminated with a full monolayer of Bi atoms which also form zigzag chains. The Bi atoms in the chains bond alternately to the first and second layer substrate atoms and the Bi chains are inclined at 34° to the surface. This new structural model explains the higher thermal stability of the 1×2 phase compared to that of the 1×1 phase.

scholarly journals Theoretical and experimental determination of mass attenuation coefficients of lead-based ceramics and their comparison with simulation

2016 ◽  
Vol 31 (2) ◽  
pp. 142-149 ◽  
Author(s):  
Alireza Vejdani-Noghreiyan ◽  
Elham Aliakbari ◽  
Atiyeh Ebrahimi-Khankook ◽  
Mahdi Ghasemifard
Keyword(s):  
Gamma Ray ◽  
Mass Attenuation Coefficient ◽  
X Ray Diffraction ◽  
Attenuation Coefficients ◽  
X Ray ◽  
Simulation Results ◽  
Theoretical Results ◽  
Good Agreement ◽  
Mass Attenuation

Mass attenuation coefficient of lead-based ceramics have been measured by experimental methods and compared with theoretical and Monte Carlo simulation results. Lead-based ceramics were prepared using mixed oxide method and the X-ray diffraction analysis was done to evaluate the crystal structure of the produced handmade ceramics. The experimental results show good agreement with theoretical and simulation results. However at two gamma ray energies, small differences between experimental and theoretical results have been observed. By adding other additives to ceramics and observing the changes in the shielding properties such as flexibility, one can synthesize and optimize ceramics as a neutron shield.

scholarly journals Microstrain Measurement in Plastically Deformed Austenitic Steel

1999 ◽  
Vol 33 (1-4) ◽  
pp. 219-230 ◽  
Author(s):  
K. Hirschi ◽  
M. Ceretti ◽  
P. Lukás ◽  
N. Ji ◽  
C. Braham ◽  
...  
Keyword(s):  
Austenitic Steel ◽  
Metallic Materials ◽  
Line Broadening ◽  
X Ray Diffraction ◽  
X Ray ◽  
Compressive Stresses ◽  
Cold Rolled ◽  
The Mean ◽  
Good Agreement

Some results of high-resolution neutron diffraction experiments resulting in determination of the microstrain in metallic materials are reported. The method of the diffraction line broadening analysis was verified in two materials, investigated earlier by X-ray diffraction: an austenitic steel prestrained up to 30% and a cold rolled aluminium magnesium alloy. For these materials, the mean-square microstrain and the dislocation density were determined, a good agreement was reached with the results of X-ray experiments. As an application of such analysis we investigated the influence of the shot-peening treatment on an austenitic steel. This treatment is commonly used to introduce compressive stresses in the surface of material, giving improved resistance to fatigue fracture. The microstrain distribution and the size of coherently diffracting blocks for a shot-peened sample of austenitic steel as a function of depth from the surface are determined by the above analysis and the results are presented.

Automatic determination of diffuse-peak positions and the centre of a diffraction pattern

1999 ◽  
Vol 32 (2) ◽  
pp. 332-335 ◽  
Author(s):  
S. J. Wilkinson ◽  
D. W. L. Hukins
Keyword(s):  
Annulus Fibrosus ◽  
Gaussian Function ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
X Ray ◽  
Oriented Molecules ◽  
Beam Stop ◽  
Diffraction Patterns ◽  
Good Agreement

Correlation with a two-dimensional Gaussian function was used to locate the positions of diffuse peaks in X-ray diffraction patterns. The centre of a pattern was defined as the centroid of the image of the undeflected beam, found by convolution with a two-dimensional Gaussian function. These methods were implemented using the IDL programing language. They were tested on diffraction patterns from systems containing oriented molecules of the protein collagen: collagen tape, elastoidin spicules and annulus fibrosus of intervertebral disc. Specimens were dusted with quartz to calibrate the diffraction patterns. These patterns were recorded on film, using a semi-transparent beam stop to obtain an image of the undeflected beam, and digitized at a resolution of 105 µm. Intermolecular spacings, calculated from the distance between a peak and the centre of a pattern, were in good agreement with those determined previously.

X-Ray Diffraction Study of Methanol-Water Mixtures

1994 ◽  
Vol 49 (10) ◽  
pp. 967-972 ◽  
Author(s):  
I. Bakó ◽  
G. Pálinkás ◽  
K. Heinzinger
Keyword(s):  
Structure Functions ◽  
Excess Functions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thermodynamic Excess Functions ◽  
The Difference ◽  
Diffraction Patterns ◽  
Molecular Dynamics Results ◽  
Experimental Structure ◽  
Good Agreement

Abstract X-ray diffraction patterns o f m ethanol-water mixtures with mole fractions of methanol molecules o f 0.1, 0.25 and 0.9 have been measured. The experimental structure functions of mixtures are compared with those of pure solvents and with recent Molecular Dynamics results. Difference structure functions similar to thermodynamic excess functions are introduced for the analysis of methanol-water interactions. The comparison of the total and the difference structure functions from experiments and simulations shows an overall good agreement.

The effect of sample position on the determination of triaxial stress by X-ray diffraction

1988 ◽  
Vol 21 (1) ◽  
pp. 38-41 ◽  
Author(s):  
R. H. Fenn ◽  
A. M. Jones
Keyword(s):  
Shear Stress ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
X Ray ◽  
Stress Components ◽  
Sample Position ◽  
Measured Strain ◽  
The Difference ◽  
Negative Sense

The determination of the full three-dimensional stress tensor in a specimen by X-ray diffraction requires that the strain be measured with the sample tilted in both a positive and a negative sense for different rotations of the sample in its own plane. The error introduced in the measured strain as a function of the position of the specimen relative to the X-ray diffractometer axis is investigated and it is shown that the negative tilt values are more sensitive to sample position than the positive tilt values. The determination of the shear stress components uses the difference between the measured strain at equivalent positive and negative tilts and hence it is shown that displacement of the sample could lead to incorrect deductions concerning the presence and magnitude of the shear stress components.

Control of geometrical sources of error in residual stress analysis by energy-dispersive X-ray diffraction

2003 ◽  
Vol 38 (4) ◽  
pp. 283-288
Author(s):  
J A Alfonso ◽  
E D Greaves ◽  
B Lavelle ◽  
L Sajo-Bohus
Keyword(s):  
Residual Stress ◽  
Theoretical Data ◽  
Energy Dispersive ◽  
Theoretical Expression ◽  
X Ray Diffraction ◽  
X Ray ◽  
Peak Energy ◽  
Evaluation And Monitoring ◽  
Good Agreement

A theoretical expression that describes the influence of instrumental errors in the determination of residual stress by energy-dispersive X-ray diffraction (EDXRD) is derived. The calculation predicts the shift in the diffraction peak energy with variation in the angle Ψ as a function of the misalignment parameters. A simple model that allows evaluation and monitoring of instrumental adjustment for residual stress measurements by EDXRD is shown. Good agreement between experimental and theoretical data is obtained using the model developed.

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