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1.
That from us as X‐ray Rotation‐Tilt Technique (XRT Method) designated procedure principle represents a world innovation and overcomes essential disadvantages of comparable diffraction techniques known up to now. Starting from the origin and the informational content of the XRT interferences a realization of a special equipment and selected examples of some first applications are presented. 相似文献
2.
The in‐plane mosaic structure of Au/Fe and GaN‐based epitaxial layers has been determined directly by laboratory‐based grazing incidence in‐plane x‐ray diffraction in which Bragg reflections normal to the plane of the wafer are probed. High intensity and acceptable signal‐to‐noise can be obtained with no modifications to commercially available equipment. Excellent agreement is obtained between measurements of the same Au/Fe multilayer samples at the European Synchrotron Radiation Facility in Grenoble and with the laboratory system employing a focused x‐ray beam from a microfocus generator. The technique is particularly important for the GaN‐based systems as it uniquely provides a measure of the so‐called twist mosaic independent of the out‐of plane (tilt) mosaic. 相似文献
3.
Usually about one micrometer is considered the lower limit of spatial resolution (in direct space) of x‐ray diffraction. This is due as well to diffraction as to image detection. The latter problem can be addressed by image magnification. There are several efforts to achieve image magnification. One is magnification by asymmetric Bragg reflection. This is well known for many years. In the present paper the implications regarding experimental set‐up, resolution and efficiency will be considered from the experimental point of view. High magnification at good spatial resolution requires synchrotron radiation. Experiments were performed at beamlines ID19 and ID11 of the European Synchrotron Radiation Facility (ESRF). It is shown that actually a spatial resolution considerable better than one micrometer can be achieved. There are, however, some drawbacks which are related to source characteristics, synchrotron beam optics, Fresnel and Bragg diffraction. 相似文献
4.
W.‐R. Liu W. F. Hsieh C.‐H. Hsu Keng S. Liang F. S.‐S. Chien 《Journal of Applied Crystallography》2007,40(5):924-930
The structures of high‐quality ZnO epitaxial films grown by pulsed‐laser deposition on sapphire (0001) without an oxygen gas flow were investigated by X‐ray diffraction and transmission electron microscopy. The great disparity of X‐ray diffraction line widths between the normal and in‐plane reflections reveals the specific threading dislocation geometry of ZnO. Most threading dislocations are pure edge dislocations. From a combination of scattering and microscopic results, it is found that threading dislocations are not uniformly distributed in the ZnO films, but the films consist of columnar epitaxial cores surrounded by annular regions of edge threading dislocations in large density. The local surface morphology and capacitance signal obtained from atomic force and scanning capacitance microscopes indicate that the aggregation of threading dislocations leads to high interface traps at the annular regions. 相似文献
5.
《Crystal Research and Technology》2018,53(2)
The crystal grain size can be quantitatively calculated by Scherrer equation according to the diffraction peak broadening in the XRD curves. Actually, the results calculated by the Scherrer equation are the thickness that perpendicular to the crystal planes. However, in the actual XRD measurements, the broadening of the diffraction peaks is not only because of the Micro‐level changes of crystal such as grain size and lattice distortion, but also due to the instrumental broadening. Thus, the Scherrer equation is less reliable if the full width at half maximum caused by the physical broadening is smaller than that caused by the instrumental broadening. In this paper, it is concluded that the applicable range of the Scherrer equation will increases with the increasing diffraction angle. As an example of Scherrer equation's application, the calculation result for the maximum applicable scope of Si(100) films is 137 nm. 相似文献
6.
SrRuO3 is a highly interesting material due to its anomalous‐metal properties related with ferromagnetism and its relevance as conductive perovskite layer or substrate in heterostructure devices. We have used optical floating zone technique in an infrared image furnace to grow large single crystals of SrRuO3 with volumes attaining several hundred mm3. Crystals obtained for optimized growth parameters exhibit a high ferromagnetic Curie temperature of 165 K and a low‐temperature magnetization of 1.6 μB at a magnetic field of 6 T. The high quality of the crystals is further documented by large residual resistance ratios of 75 and by crystal structure and chemical analyzes. With these crystals the magnetic anisotropy could be determined. 相似文献
7.
V. Rajnikant V.K. Gupta S. Shafi E.H. Khan J. Firoz R. Gupta 《Crystal Research and Technology》2001,36(2):215-221
The crystal and molecular structure of 3 β ‐Acetoxy‐5 α ‐cholestan‐6‐one has been determined by X‐ray crystallographic techniques. The compound crystallizes in the space group P21 with cell parameters : a = 13.060(3), b=6.299(2), c=17.152(6)Å; β =96.47(3)o, V = 1402.02Å3, Z = 2, R = 0.072 for 1921 observed reflections. The six‐membered rings (A, B and C) exist in the chair conformations while the five‐membered ring‐d assumes half‐chair. All rings of the steroid skeleton are trans connected. 相似文献
8.
E. Zielinska‐Rohozinska M. Kowalska K. Paku&#x;a 《Crystal Research and Technology》2003,38(11):951-955
AlxGa1‐xN/GaN (Si doped or undoped) with the Al content in the composition range of 0.046 ≤ x ≤ 0.164 grown on the c sapphire face by atmospheric pressure MOCVD method were studied by high resolution x‐ray diffraction including symmetrical and asymmetrical ω/2θ scans and reciprocal space maps. A high sensitivity to small inhomogeneities of the layer thickness and lattice mismatch between AlGaN and GaN is reported, recognised as changes in the interference pattern of the diffraction peak observed across the sample. They are very well correlated with optical properties derived from independent photoreflectivity measurements. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
9.
Ashish Bhatnagar Sunita K. Pandey Rohit R. Shahi M. Sterlin Leo Hudson M. A. Shaz O. N. Srivastava 《Crystal Research and Technology》2013,48(8):520-531
The aim of the present investigation is to synthesize mixed sodium potassium alanate (K2NaAlH6) and to explore its hydrogen sorption characteristics. K2NaAlH6 is synthesized through ball milling of KH and NaAlH4 in the molar ratio 2:1 under hydrogen pressure of 10 bar. The temperature programmed desorption experiment shows that the synthesized K2NaAlH6 has peak desorption temperature of ∼352°C and reveals appreciable rehydrogenation kinetics under 6 bar hydrogen pressure at 300°C. The investigations are also focused on the catalytic effect of carbon nanostructures (CNS) namely, the graphene sheet (GS) and single wall carbon nanotube (SWCNT) and titanium halides (TiCl3 and TiF3) on K2NaAlH6. In the case of graphene and SWCNT catalyzed K2NaAlH6, the peak desorption temperature gets reduced to ∼347°C and ∼341°C respectively. The catalytic effects of CNS and titanium halide on K2NaAlH6 are also compared in the investigation. Between the two types of catalysts, halides are found to be better than CNS and out of the two halides, TiF3 is found to be the best catalyst for hydrogen sorption in K2NaAlH6. The peak desorption temperature decreases significantly from 352°C to ∼324°C for TiF3 catalyzed K2NaAlH6. Thus, the desorption activation energy reduces drastically from 124.43 kJ/mol (synthesized K2NaAlH6) to 88.05 kJ/mol for TiF3 catalyzed K2NaAlH6. 相似文献
10.
P. Nisha Santha Kumari M. Beatrice Margaret S. Kalainathan 《Crystal Research and Technology》2009,44(2):177-183
Pure and potassium doped cadmium mercury thiocyanate single crystals have been obtained from silica gel by the process of diffusion. The X‐ray diffraction studies reveal the crystal lattice of both pure and doped crystals to be tetragonal. The crystalline perfection of the grown crystals were investigated by high resolution X‐ray diffraction analysis and the quality of the crystals are found to be extremely good. Transmission and Fourier transform infrared spectra were recorded for the grown crystals. The TG/DTA analyses show that the crystals are highly thermally stable. The mechanical strength of the crystals were studied by Vickers microhardness test and a study of their second harmonic generation efficiency in comparison with urea has been made by performing Kurtz powder test. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
11.
Single crystals of CdGa2(1‐x)Cr2xSe4 compounds for 0 ≤ x ≤ 1 have been grown by using the chemical vapor transport technique in a closed system. The transporting agent was CdCl2 in a proportion of 0.75 mg/cc of capsule. The starting material was previously synthetized. The structural characterization on the crystals were done by powder x‐ray diffraction studies. The results show three different phases for various Cr concentration ranges: spinel structure for x ≥ 0.7, rombohedral for 0.6 ≥ x ≥ 0.5 and tetragonal for 0.4 ≥ x ≥ 0. That is, the chromium dilution in the CdCr2Se4 compound by Ga atoms produces very significant changes in the structural atomic arrangement. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
12.
S. P. Chandini Sam V. S. Prasad K. Sudarsana Kumar 《Crystal Research and Technology》2010,45(11):1199-1203
This paper embodies the result of the investigations carried out on the synthesis of zirconia‐ rare earth mixed oxide pigments: ZrCe1‐xYxO4‐δ and ZrCe1‐xPrxO4‐δ by the solution combustion method and their characterization by X‐ray powder diffraction, transmission electron microscopy, energy dispersive spectrometric analysis, thermal analysis, reflectance spectral data and surface area measurements. The synthesized nano pigments possess low a and high b and exhibit yellow color when doped with Y and changes from yellow to orange‐red color when doped with Pr, with increase in x values. These pigments show maximum reflectance of 90% when the wavelength is above 550 nm. Due to the homogeneity of the phase formed and resistance to water, acids and alkali, the rare earth mixed oxides developed are found to be promising candidates as nontoxic pigments. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
13.
Emil Zolotoyabko 《Journal of Applied Crystallography》2013,46(6):1877-1879
Interrelations between the degree of uniaxial preferred orientation and the intensities and widths of selected X‐ray diffraction peaks are analyzed within the March–Dollase approach. Simple analytical expressions are developed which relate the degree of preferred orientation to the rocking curve width of the strongest diffraction peak or the intensity ratio of two diffraction peaks, one of them being originated in the preferably orientated atomic planes. 相似文献
14.
CuInSe2, CuGaSe2, Cu(In,Ga)Se2 and CuInS2 thin‐film solar absorbers in completed solar cells were studied in cross section by means of electron‐backscatter diffraction. From the data acquired, grain‐size distributions were extracted, and also the most frequent grain boundaries were determined. The grain‐size distributions of all chalcopyrite‐type thin films studied can be described well by lognormal distribution functions. The most frequent grain‐boundary types in these thin films are 60°−〈221〉tet and 71°−〈110〉tet (near) Σ3 twin boundaries. These results can be related directly to the importance of {112}tet planes during the topotactical growth of chalcopyrite‐type thin films. Based on energetic considerations, it is assumed that the most frequent twin boundaries exhibit a 180°−〈221〉tet constellation. 相似文献
15.
16.
Angelika Dorothea Rosa Nadge Hilairet Sujoy Ghosh Gaston Garbarino Jeroen Jacobs Jean‐Philippe Perrillat Gavin Vaughan Sbastien Merkel 《Journal of Applied Crystallography》2015,48(5):1346-1354
Microstructures govern the mechanical properties of materials and change dramatically during phase transformations. A detailed understanding of microstructures at different stages of a transformation is important for the design of new materials and for constraining geophysical processes. However, experimental studies of transformation microstructures at the grain scale have been mostly based on ex situ observations of quenched products, which are difficult to correlate with bulk sample properties and transformation kinetics. Here, it is shown how multi‐grain crystallography on polycrystalline samples, combined with a resistively heated diamond anvil cell, can be applied to investigate the microstructural properties of a material undergoing a phase transition in situ at high pressure and high temperature. This approach allows the extraction of the crystallographic parameters and orientations of several hundreds of grains inside a transforming sample. Important bulk information on grain size distributions and orientation relations between the parent and the newly formed phase at the different stages of the transformation can be monitored. These data can be used to elucidate transformation mechanisms (e.g. coherent versus incoherent growth), growth rates and orientation‐dependent growth of individual grains. The methodology is demonstrated on the α–γ phase transitions in hydrous Mg2SiO4·H2O up to 22 GPa and 940 K. This transformation most likely occurs in the most abundant mineral of the Earth's upper mantle (Mg0.8Fe0.2SiO4) in deep cold subducted slabs and plays an important role in their subduction behaviour. 相似文献
17.
Phosphor material BaAl2O4:Eu2+, Cr3+ with varying concentrations of Cr co‐doping were prepared by solid‐state synthesis method. Crystalline fibres were obtained by controlled annealing temperature. Synthesized compositions were characterized for their phase and crystallinity by powder x‐ray diffraction. The crystalline morphology was investigated using SEM analysis. High resolution transmission electron microscopy (HRTEM) in image and diffraction modes was used to investigate the microstructure. The effect of Cr doping on quality and morphology of grown crystals was investigated. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
18.
The diffraction rings that arise in X‐ray scattering experiments frequently exhibit non‐uniformity or `spottiness' as a result of the finite number of grains within the probed volume. This article explores a variety of ways to assess this graininess and shows that scaling relationships can be used to quantitatively relate ring non‐uniformity to the number of grains within the scattering volume. The applicability of the method is demonstrated for grain counts from 10 to 107, enabling measurement of the crystalline fraction or of the average grain size from 6 nm to 120 µm. This method enables quantification of grain size even in cases where the intrinsic peak width is much smaller than the instrumental broadening. The method is validated with experimental measurements on a variety of systems. 相似文献
19.
T. Markussen Xiaowei Fu L. Margulies E. M. Lauridsen S. F. Nielsen S. Schmidt H. F. Poulsen 《Journal of Applied Crystallography》2004,37(1):96-102
A reconstruction method is presented for generation of three‐dimensional maps of the grain boundaries within powders or polycrystals. The grains are assumed to have a mosaic spread below 1°. They are mapped by diffraction with a wide beam of hard X‐rays, using a setup similar to that of parallel‐beam absorption contrast tomography. First the diffraction spots are sorted with respect to grain of origin. Next, for each grain the reconstruction is performed by an algebraic algorithm known as three‐dimensional ART. From simulations it is found that reconstructions with a spatial accuracy better than the pixel size of the detector can be obtained from as few as five diffraction spots. The results are superior to three‐dimensional reconstructions based on the same data using a variant of the filtered back‐projection algorithm. In comparison with layer‐by‐layer type reconstructions based on the two‐dimensional ART algorithm, as introduced by Poulsen & Fu [J. Appl. Cryst. (2003), 36 , 1062–1068], the quality of the maps is found to be similar, provided that five to ten spots are available for analysis, while data acquisition with the three‐dimensional method is much faster. The three‐dimensional ART methodology is validated on experimental data. With state‐of‐the‐art detectors, the spatial accuracy is estimated to be 5 µm. 相似文献
20.
Mixed crystals of ammonium dihydrogen phosphate and potassium dihydrogen phosphate K1‐x(NH4)x H2PO4 were grown from aqueous solutions with x = 0.06, 0.09, 0.15, 0.32, 0.42, 0.51, 0.63, 0.70, 0.76, 0.78, 0.84, 0.88, 0.89 and 0.91. The crystal composition that differs from solution was estimated by X‐ray method. Morphology of the crystals changes from tetragonal prism to needles when the incorporation of either of the two components into the other; which also affects the growth rate along the prominent growth directions significantly. Growth along the [001] decreases initially with composition and reached the maximum when x = 0.5; whereas growth along the [100] always showed a decreasing trend with composition and attained a minimum value when x = 0.5. Crystal length along the [001] and [100] and aspect ratio are also compositional dependent. Unit cell parameters determined by X‐ray powder and single crystal analyses revealed that the ‘a ’ parameter shows only a small and linear variation but the ‘c ’ parameter changes significantly with ADP incorporation because of the difference in the effective ionic radius of K+ and NH4+ ions and also the possibility of NH4+ ion to form two different kinds of hydrogen bonds in the system. The existence of a pseudo‐cubic cell at the mixing composition x = 0.78 was also revealed. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献