Theory of X-ray reflection broadening for textures with double-axis averaging: from semicrystalline polymers exhibiting twisted lamellar growth to discotic liquid crystals

It is shown that textures with double-axis averaging similar to thea-texture, or Keller–Machin Type I texture, are not specific to semicrystalline polymers exhibiting twisted lamellar growth. In this work, such texture is observed in extruded fibers of a typical discotic molecule,trans-diC60-Zn porphyrin. Experimentally, these textures can be detected from the characteristic `comma'-like azimuthal profiles of the non-equatorial diffraction peaks in two-dimensional X-ray patterns. Analytical expressions for the azimuthal intensity distribution are developed, which are in good agreement with the experiment. In the proposed generalized coordinates, the diffraction peak shape becomes universal. This provides a simple means of checking the closeness of the sample morphology to thea-texture from just one two-dimensional pattern, without constructing the whole X-ray pole figure.

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Experimental Study of Precise Peak Determination in X-Ray Powder Diffraction

Advances in X-ray Analysis ◽

10.1154/s0376030800016955 ◽

1983 ◽

Vol 27 ◽

pp. 53-60 ◽

Cited By ~ 1

Author(s):

T. C. Huang ◽

W. Parrish ◽

G. Lim

Keyword(s):

X Ray Diffraction ◽

X Ray ◽

Search Results ◽

Profile Fitting ◽

Derivative Method ◽

Diffraction Peaks ◽

Peak Search ◽

Different Characteristics ◽

Good Agreement ◽

Statistical Noise

AbstractThe combined derivative method (accompanying paper) was tested with a large number of experimental patterns to illustrate its use in various difficult problems commonly arising in peak search analysis of X-ray diffraction data. Patterns obtained with various step sizes, resolution, counting statistical noise, and profile widths were used. The precision in 2θ determination and overlap resolution are in good agreement with those previously obtained from calculated profiles, raise identification of noise as diffraction peaks was eliminated by using a convolution range proportional to the full width at half maximum. Peak search results (both 2θ and intensity) were also compared to those obtained by profile fitting to illustrate the different characteristics of these two methods.

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Effects of Materials on Formation of Double-Layered Liners Shaped Charges

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.79-82.1277 ◽

2009 ◽

Vol 79-82 ◽

pp. 1277-1280

Author(s):

Yu Zheng ◽

Xiao Ming Wang ◽

Wen Bin Li ◽

Wen Jin Yao

Keyword(s):

Numerical Simulation ◽

Finite Element ◽

Numerical Simulations ◽

Double Layer ◽

Two Dimensional ◽

Materials Properties ◽

X Ray ◽

Dimensional Finite Element ◽

Simulation Results ◽

Good Agreement

In order to study the effects of liner materials on the formation of Shaped Charges with Double Layer Liners (SCDLL) into tandem Explosively Formed Projectile (EFP), the formation mechanism of DLSCL was studied. Utilizing two-dimensional finite element dynamic code AUTODYN, the numerical simulations on the mechanical phenomenon of SCDLL forming into tandem EFP were carried out. X-ray pictures were obtained after Experiments on SCDLL. Comparisons between experimental results and numerical simulation results have good agreement. It can be concluded from the results that the materials properties and configurations of both liners are crucial to the formation of tandem EFP.

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ANHARMONIC EFFECTIVE POTENTIAL, LOCAL FORCE CONSTANT AND EXAFS OF HCP CRYSTALS: THEORY AND COMPARISON TO EXPERIMENT

International Journal of Modern Physics B ◽

10.1142/s0217979208049285 ◽

2008 ◽

Vol 22 (29) ◽

pp. 5155-5166 ◽

Cited By ~ 11

Author(s):

NGUYEN VAN HUNG ◽

TONG SY TIEN ◽

LE HAI HUNG ◽

RONALD R. FRAHM

Keyword(s):

Thermal Expansion ◽

Fine Structure ◽

Thermal Expansion Coefficient ◽

Force Constant ◽

Expansion Coefficient ◽

Effective Potential ◽

X Ray ◽

X Ray Absorption ◽

Analytical Expressions ◽

Good Agreement

Anharmonic effective potential, Extended X-ray Absorption Fine Structure (EXAFS) and its parameters of hcp crystals have been theoretically and experimentally studied. Analytical expressions for the anharmonic effective potential, effective local force constant, three first cumulants, a novel anharmonic factor, thermal expansion coefficient and anhamonic contributions to EXAFS amplitude and phase have been derived. This anharmonic theory is applied to analyze the EXAFS of Zn and Cd at 77 K and 300 K, measured at HASYLAB (DESY, Germany). Numerical results are found to be in good agreement with experiment, where unnegligible anharmonic effects have been shown in the considered theoretical and experimental quantities.

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Divergent-beam X-ray photography of crystals

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1947.0002 ◽

1947 ◽

Vol 240 (817) ◽

pp. 219-250 ◽

Cited By ~ 118

Keyword(s):

Wave Length ◽

Impurity Content ◽

Type I ◽

X Rays ◽

Divergent Beam ◽

X Ray ◽

Air Temperatures ◽

High Degree ◽

Good Agreement

Divergent-beam X-ray photography of single crystals by transmission can be used to study the ‘extinction’, that is, the diminution of the transmitted radiation that takes place at the Bragg reflexion angles. The intensity and geometry of the absorption lines observed give useful information about the texture of the crystal. Divergent beam photographs have shown that many crystals of organic compounds are unexpectedly perfect, and that sudden cooling to liquid-air temperatures will increase the mosaic character of their structure by an important factor and make them more suitable for structural analysis by the usual methods. Type I diamonds, and natural ice even near to its melting-point, are also found to possess a high degree of perfection, which cannot be removed by liquid-air treatment. The divergent beam method may be used for the determination of orientation, but it is important that the wave-length of X-rays employed should be correctly related to the size and nature of the crystal. In certain favourable cases it is possible to make precision measurements of lattice constant or of wave-length from divergent beam photographs, without the use of any kind of precision apparatus. By such means it has been shown that the C—C distance in individual diamonds varies from 1541.53(± 0-02) to 1541.27X, (1.54465-1-54440A), a difference presumably due to varying impurity content. Using diamond and a brass anticathode, the Zn Ka 1 wave-length, relative to Cu K Ka 1 as 1537.40X, is found to be 1432.21 ( ± 0-04) X. Temperature control would improve the accuracy of this measurement, which is, however, in good agreement with the latest value obtained by orthodox precision methods.

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Periodicities in the X-Ray Diffraction of Low Order ALAS/GAAS Superlattices

MRS Proceedings ◽

10.1557/proc-230-219 ◽

1991 ◽

Vol 230 ◽

Author(s):

Joseph Pellegrino ◽

S. Qadri ◽

W. Tseng ◽

W. R. Miller ◽

J. Comas

Keyword(s):

Growth Conditions ◽

X Ray Diffraction ◽

Satellite Peak ◽

X Ray ◽

Migration Enhanced Epitaxy ◽

Diffraction Peaks ◽

Superlattice Structures ◽

And Migration ◽

Possible Cause ◽

Good Agreement

AbstractIn this work we examine the physical properties for the superlattice system (GaAs)n1 (AlAs)n2/GaAs(100) for low values of n1 and n2, i.e., n1 = n2 = 3, 6, 12. Normal, interrupted growth, and migration enhanced epitaxy (MEE) growth techniques were used to grow the superlattice structures in a molecular beam epitaxy system. X-ray diffraction spectra were obtained, and the major and satellite peak positions were analyzed to obtain the superlattice periodicity. An analysis of the major diffraction peaks and their associated satellites produced superlattice periodicity in good agreement with theory. Diffraction peaks were also observed in regions adjacent to the primary diffraction peaks which did not occur in the expected satellite positions. An analysis of these peaks relative to the primary peak indicate periodicities corresponding to layer thickness greater than the intended period. One possible cause for these periodicities is growth conditions that exist during the growth of the superlattice which result in the deposition of fractional monolayers. In this study we present results which suggest that an arsenic-deficient growth condition may be a contributing factor in the deposition of fractional monolayers.

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Microwave-Assisted Preparation of Zinc-Doped β-Tricalcium Phosphate for Orthopedic Applications

Indonesian Journal of Chemistry ◽

10.22146/ijc.55931 ◽

2020 ◽

Author(s):

Ali Taha Saleh ◽

Dheyaa Alameri

Keyword(s):

Tricalcium Phosphate ◽

Degree Of Crystallinity ◽

X Ray Diffraction ◽

X Ray ◽

Microwave Assisted ◽

Ftir Spectrometer ◽

Diffraction Peaks ◽

Orthopedic Applications ◽

The Degree Of Crystallinity ◽

Good Agreement

A novel two-step methodology delivering zinc into the structure of β-tricalcium phosphate (β-TCP) has been investigated. Incorporating wet precipitation of calcium-deficient apatite [Ca9-xZnx(HPO4)(PO4)5(OH)] (x = 0.00–1.00 mol) using a microwave-assisted process followed by two-hour calcination at 1000 °C has been conducted to generate a ratio of 1.48 of Zn doped β-TCP. The products were characterized by X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectrometer, and field emission scanning electron microscope (FESEM). Our results confirmed that the product was crystalline Zn2+-doped β-tricalcium phosphate. The incorporation of Zn+2 into the β-TCP lattice resulted in a shifting of diffraction peaks to higher 2θ values, which were attributed to the substitution of larger-sized Ca+2 ions with smaller-sized Zn2+ ions. A reduction in the intensity of the XRD peaks was also observed due to the reduction in the degree of crystallinity of the samples. Lattice parameters along the a and c-axis showed a gradual decrease in length with an increase in the amount of Zn2+ doping. This decrease was attributed to the replacement of Ca+2 ion by the smaller-sized Zn2+ ions. The microstructure of the powders consisted of microscale aggregates fused together. EDX analysis of all samples showed that the Zn2+ doping had successfully taken place and the amount of Zn2+ present in the samples was in good agreement with the theoretical values.

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SÍNTESIS DE YAIO3 (YAP) POLICRISTALINO POR EL MÉTODO DE COMBUSTIÓN EN SOLUCIÓN

Revista TECNIA ◽

10.21754/tecnia.v27i1.126 ◽

2018 ◽

Vol 27 (1) ◽

pp. 61

Author(s):

A. Lazo ◽

C. Paucarchuco ◽

H. Loro

Keyword(s):

Combustion Process ◽

Orthorhombic Phase ◽

Combustion Method ◽

X Ray Diffraction ◽

Solution Combustion ◽

X Ray ◽

Structure And Morphology ◽

Palabras Clave ◽

Diffraction Peaks ◽

Ray Patterns

Se presenta el método de combustión en solución y su aplicación para la síntesis de YAlO3 (YAP), fueron usados como combustibles para la reacción de combustión y síntesis la urea y glicina, del YAP. Usando las técnicas de difracción de rayos X (XRD) por el método del polvo y microscopia electrónica de barrido (MEB) fueron analizadas la parte estructural y morfológica de las muestras obtenidas. Los difractogramas de Rayos X muestran una excelente correspondencia con lo reportado en la literatura para este material. Se suministran también los resultados de las muestras de material YAlxCrx‐1O3, dopado con Cr3+ con x = 0.001, 0.01, que exhiben picos de difracción dominantes debidos a la fase ortorrómbica de YAlO3 Palabras clave.- YAP, YAlO3, Combustion method. ABSTRACT The solution‐combustion process is presented, as well as its application to the synthesis of YAlO3 (YAP). Urea and glycine were used as fuel for the combustion reaction and synthesis of the YAP. The structure and morphology of the obtained sample were analyzed using the X‐ray diffraction (XRD) powder method and scanning electron microscopy (SEM). The X‐ray patterns showed an excellent agreement with data reported in the literature for this material. Results are also given for samples of YAlxCrx‐1O3 doped with Cr3+, with x = 0.001, 0.01, which showed dominant diffraction peaks due to the orthorhombic phase of YAlO3. Keywords.- YAP, YAlO3, combustion method.

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X-ray diffraction curves for a system of parallel cylinders with liquid-like order: A model for the diffraction of crazed polymers

Journal of Applied Crystallography ◽

10.1107/s0021889881009680 ◽

1981 ◽

Vol 14 (6) ◽

pp. 417-420 ◽

Cited By ~ 1

Author(s):

E. Paredes ◽

P. Colonomos

Keyword(s):

Monte Carlo ◽

Distribution Function ◽

Radial Distribution Function ◽

Internal Structure ◽

Two Dimensional ◽

X Ray Diffraction ◽

Monte Carlo Data ◽

X Ray ◽

Fibril Diameter ◽

Good Agreement

As a model for the internal structure of polymer crazes, a system of parallel cylinders with liquid-like order is proposed. X-ray diffraction curves were calculated for such a system with Monte Carlo data for the radial distribution function of the two-dimensional hard-disk fluid at different packing densities. A comparison is made between the present calculations and experimental results of crazed polycarbonate showing a very good agreement. A way of evaluating the average craze fibril diameter with the calculations is also discussed.

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Crystal Structures of Epitaxially Grown Fe16N2 Single Crystal Films with Giant Magnetic Moments

MRS Proceedings ◽

10.1557/proc-263-341 ◽

1992 ◽

Vol 263 ◽

Cited By ~ 1

Author(s):

Matahiro Komuro ◽

Hiroyuki Hoshiya ◽

Hiroaki Takahashi ◽

Katsuya Mitsuoka ◽

Yutaka Sugita

Keyword(s):

Crystal Orientation ◽

Magnetic Moments ◽

Diffraction Method ◽

Lattice Parameters ◽

X Ray Diffraction ◽

X Ray ◽

Single Crystal Films ◽

Crystal Films ◽

Diffraction Peaks ◽

Good Agreement

ABSTRACTLattice parameters and crystal orientation for Fe1 6.N2 were determined by an X-ray diffraction method using a three axes goniometer. The lattice parameters of the a-axis and c-axis(a0, c0.) are 5.71 !A and 6.33 !A, respectively. The co corresponds to that of In0, 2,Gao.,s As substrates. Crystal orientation between Fe1 5.N2. films and Ino.,2Gao.,8 As is Fe1 0N2(001)//In0 2.Ga0.2 As(1001) and Fe1 0.N2.(100)//In02Ga0.6As(100). Intensity ratios for these diffraction peaks are in good agreement with calculated values proposed by Jack.

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