The Bragg equation, nλ = 2dsinθ is one of the keystones in understanding X-ray diffraction. X-ray diffraction techniques have, therefore, been widely used as an indispensable means in materials research, development and production. The properties and functions of materials largely depend on the crystal structures. X-ray diffraction techniques are superior in elucidating the three-dimensional atomic structure of crystalline solids. X-ray diffraction techniques are used for the identification of crystalline phases of various materials and the quantitative phase analysis subsequent to the identification. Rigaku has developed a range of X-ray diffractometers, in co-operation with academic and industrial users, which provide the most technically advanced, versatile and cost-effective diffraction solutions available today. From research to production and engineering, XRD is an indispensable method for materials characterization and quality control. X-ray diffraction (XRD) is one of the most important non-destructive tools to analyze all kinds of matter-ranging from fluids, to powders and crystals. XRD tends to probe much deeper than these techniques, providing more bulk information unless grazing incidence (GI-XRD) is used to enhance the surface sensitivity of the technique.Determine the three dimensional structure of matter XRD can provide phase, orientation, and other crystalline information to complement the compositional results from RBS, Auger, or XPS. XRD can be quite powerful when combined with other techniques used for thin film analysis, such as Rutherford Backscattering Spectroscopy, Auger and X-ray Photoelectron Spectroscopy. It should be noted that by itself XRD cannot provide unequivocal compositional information because it is possible that a sample may have an amorphous component that cannot be identified by XRD. While these other techniques provide compositional information, XRD provides crystalline information helping to provide a more complete characterization of the material. XRD is a good complement to bulk analysis techniques such as Glow Discharge Mass Spectrometry, Inductively Coupled Plasma-Optical Emission Spectroscopy (or Mass Spectrometry), and X-ray Fluorescence. Diffraction patterns can be checked against large libraries of patterns from known materials in order to identify/quantify the phases present in a sample. Consequently, the X-ray diffraction pattern is the fingerprint of periodic atomic arrangements in a given material. Any change or difference in lattice spacing results in a corresponding shift in the diffraction lines. Where n is an integer denoting the order of the reflection, λ is the X-ray wavelength, d is the lattice spacing of the crystal planes of interest, and θ is the diffraction angle. X-ray diffraction occurs at specific angles (2θ) with respect to the lattice spacings defined by Bragg’s Law: X-rays are diffracted by the repeating lattice spacings of crystalline materials, whereas they are simply scattered by amorphous materials. In XRD analysis a sample is exposed to a collimated X-ray beam of specific known wavelength. If the material is crystalline, it possesses a three dimensional ordering or “structure” with repeat units of atomic arrangement (unit cells). Compositional results would (ideally) show a 2:1 ratio of O:Ti, but these different phases of TiO 2 have different physical and electronic properties so knowing which phase is present can be crucial. The XRD results in figure 1 show that the sample contains both the Rutile (31.4%) and Anatase (68.6%) phases of TiO 2. Shown below is the diffraction pattern from a TiO 2 sample. Please see our XRD application notes for more specific examples. XRD has a very wide range of applications, across many sample types and materials. While most other analytical techniques provide elemental or molecular information from a sample, XRD is unique in providing a wide variety of information on structures, crystalline phases, preferred crystal orientations (texture), and other structural parameters such as crystallite size, percent crystallinity, strain, stress, and crystal defects. X-ray Diffraction (XRD) is a powerful nondestructive technique for characterizing crystalline materials.
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