X-ray diffraction and heterogeneous materials: An adaptive crystallography approach (original) (raw)
Related papers
Journal of Applied Crystallography, 2015
Archaeological artefacts are often heterogeneous materials where several phases coexist in a wide grain size distribution. Most of the time, retrieving structure information at the micrometre scale is of great importance for these materials. Particularly, the organization of different phases at the micrometre scale is closely related to optical or mechanical properties, manufacturing processes, functionalities in ancient times and long-term conservation. Between classic X-ray powder diffraction with a millimetre beam and transmission electron microscopy, a gap exists and structure and phase information at the micrometre scale are missing. Using a micrometre-size synchrotron X-ray beam, a hybrid approach combining both monochromatic powder micro-diffraction and Laue single-crystal micro-diffraction was deployed to obtain information from nanometre- and micrometre-size phases, respectively. Therefore providing a way to bridge the aforementioned gap, this unique methodology was applied...
X-Ray Diffraction and Characterization of Crystalline Materials
International Conference on Information Engineering, Management and Security 2014, 2014
X-ray crystallography is a tool used for determining the atomic and molecular structure of a crystals .Although Bragg's law nλ = 2d sinΘ was used to explain the interference pattern of X-rays scattered by crystals, diffraction has been developed to study the structure of all states of matter with any beam, e.g., ions, electrons, neutrons, and protons, with a wavelength similar to the distance between the atomic or molecular structures of interest.The method also revealed the structure and function of many biological molecules, including vitamins, drugs, proteins and nucleic acids such as DNA. X-ray crystallography is still the chief method for characterizing the atomic structure of new materials and in discerning materials that appear similar by other experiments.
Method of X-Ray Diffraction Data Processing for Multiphase Materials with Low Phase Contents
Ukrainian Journal of Physics, 2019
Amorphous, glass, and glass-ceramic materials practically always include a significant number (more than eight) of crystalline phases, with the contents of the latter ranging from a few wt.% to several hundredths or tenths of wt.%. The study of such materials using the method of X-ray phase analysis faces difficulties, when determining the phase structure. In this work, we will develop a method for the analysis of the diffraction patterns of such materials, when diffraction patterns include X-ray lines, whose intensities are at the noise level. The identification of lines is based on the search for correlations between the experimental and test lines and the verification of the coincidence making use of statistical methods (computer statistics). The method is tested on the specimens of a-quartz, which are often used as standard ones, and applied to analyze lava-like fuel-containing materials from the destroyed Chornobyl NPP Unit 4. It is shown that the developed technique allows X-r...
Method for Identifying Crystalline Phases in X-ray Diffraction Data from Multiphase Samples
arXiv (Cornell University), 2021
Nat. Acad. of Sci. of Ukraine and 36a, Kirova str., Chornobyl 07270, Ukraine * A new method for identifying crystalline phases in X-ray diffraction data has been proposed, which is especially useful for the study of multiphase materials (more than eightten phases) with a relatively low content (less than 1-3 wt%). The method is based on a statistical analysis of data and provides an unambiguous non-quantitative criterion for the presence of one or another phase in the material. It has been shown that the method works reliably in cases where a significant number of reflexes (more than several dozen) on the diffraction pattern are comparable with intensity-to-noise ratio.
X-ray diffraction (XRD) mapping consists in the acquisition of XRD patterns at each pixel (or voxel) of an area (or volume). The spatial resolution ranges from the micrometer (mXRD) to the millimeter (MA-XRD)s cale, making the technique relevant for tiny samples up to large objects. Although XRD is primarily used for the identification of different materials in (complex) mixtures, additional information regarding the crystallite size, their orientation, and their indepth distribution can also be obtained. Through mapping, these different types of information can be located on the studied sample/object. Cultural heritage objects are usually highly heterogeneous, and contain both original and later (degradation, conservation) materials. Their structural characterization is required both to determine ancient manufacturing processes and to evaluate their conservation state. Togetherw ith other mapping techniques, XRD mapping is increasingly used for these purposes. Here, the authors review applicationsa sw ell as the various configurations for XRD mapping (synchrotron/laboratory X-ray source, poly-/monochromatic beam,micro/macro beam, 2D/3D, transmission/reflectionm ode). Ongoing hardware and software developments will further establish the technique as ak ey tool in heritage science.
X - RAY DIFFRACTION: Instrumentation and Applications
Critical reviews in analytical chemistry / CRC, 2015
X-ray diffraction (XRD) is a powerful nondestructive technique for characterizing crystalline materials. It provides information on structures, phases, preferred crystal orientations (texture), and other structural parameters, such as average grain size, crystallinity, strain, and crystal defects. X-ray diffraction peaks are produced by constructive interference of a monochromatic beam of X-rays scattered at specific angles from each set of lattice planes in a sample. The peak intensities are determined by the distribution of atoms within the lattice. Consequently, the X-ray diffraction pattern is the fingerprint of periodic atomic arrangements in a given material. This review summarizes the scientific trends associated with the rapid development of the technique of X-ray diffraction over the past five years pertaining to the field of pharmaceutical industry, forensic science, geological applications, microelectronics and glass industry, as well as in corrosion analysis.
Advances in Materials Physics and Chemistry, 2013
Fitting of full X-ray diffraction patterns is an effective method for quantifying abundances during X-ray diffraction (XRD) analyses. The method is based on the principal that the observed diffraction pattern is the sum of the individual phases that compose the sample. By adding an internal standard (usually corundum) to both the observed patterns and to those for individual pure phases (standards), all patterns can all be normalized to an equivalent intensity based on the internal standard intensity. Using least-squares refinement, the individual phase proportions are varied until an optimal match is reached. As the fitting of full patterns uses the entire pattern, including background, disordered and amorphous phases are explicitly considered as individual phases, with their individual intensity profiles or "amorphous humps" included in the refinement. The method can be applied not only to samples that contain well-ordered materials, but it is particularly well suited for samples containing amorphous and/or disordered materials. In cases with extremely disordered materials where no crystal structure is available for Rietveld refinement or there is no unique intensity area that can be measured for a traditional RIR analysis, full-pattern fitting may be the best or only way to readily obtain quantitative results. This approach is also applicable in cases where there are several coexisting highly disordered phases. As all phases are considered as discrete individual components, abundances are not constrained to sum to 100%.
X-ray Diffraction: A Practical Approach
Microscopy and Microanalysis, 1998
X-ray Diffraction: A Practical Approach, C. Suryanarayana and M. Grant Norton, 1998. Plenum Press, New York and London. xiii + 273 pages. (hardback, 49.50,U.S.andCanada;49.50, U.S. and Canada; 49.50,U.S.andCanada;59.40, elsewhere).It is the aim of this text to teach undergraduates majoring in materials science the use of powder X-ray diffraction for materials characterization. Since it does not treat X-ray diffraction and crystallography in a general way, it would have been better if it were given a more specific title, such as X-Ray Powder Diffraction for Metallurgical Characterization. A Primer and Workbook. As a laboratory course with work pages to be filled out by the student, it might have been spiral-bound to facilitate such use.
Phase changes in : A synchrotron X-ray powder diffraction study
Solid State Communications, 2010
A temperature dependent synchrotron X-ray powder diffraction study has been carried out on Na 1/2 Pr 1/2 TiO 3 up to 850°C. The compound shows orthorhombic (Pbnm) → orthorhombic (Ibmm) → tetragonal (I4/mcm) transitions at ∼150°C, and ∼750°C, respectively. An unusual volume expansion below 500°C has been noticed in the Ibmm phase, suggesting the onset of another, yet unknown, physical phenomenon unrelated to the crystallographic changes below this temperature.