XRD Techniques
X-ray diffraction (XRD) is a technology that provides detailed information about the chemical composition and crystallographic structure of a natural or man-made object. It does not work upon the principal of a typical x-ray in revealing the interior parts of an object. Rather, an XRD device fires x-rays at a specimen and measures the angles and direction of the beams' diffraction at the atomic level. By this measurement, scientists can assess the chemical composition and crystallographic structure of the object under study.-
Powder Diffraction
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Powder XRD may be the most common technique of x-ray diffraction. The specimen consists of grains of the material under analysis. Powder diffraction may also be used for studying specimens in liquid suspensions. The term "powder" does not refer to a powder sample but rather that the crystalline domains are randomly oriented in the specimen. The results from a powder XRD consist of the positions and intensities of peaks that identify the underlying structure of the specimen. By this means, diamond or graphite will produce differing results even though both consist of carbon on the atomic level.
Thin Film Diffraction
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Thin film diffraction is not as much a single XRD technique as a collection of techniques to analyze thin film samples grown on substrates. This technique is often used in the research and development of microelectronic and optoelectronic devices. This method is particularly useful in measuring precise lattice constants which can help measure the structural and residual stress in a material.
XRD Analysis Techniques
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Qualitative analysis of XRD measurements identifies the underlying structure of a specimen by comparing it with data collected from similar materials. It requires precise measurements of peak positions and intensities to make an accurate determination of the diffraction system. Quantitative analysis of XRD data measures the underlying structure of samples that do not keep a constant form, such as multiphase specimens. In other words, it tries to assess the properties of a material whose structure is always changing through a number of phases. The most effective methods of quantitative evaluation are very complex and require powerful computers for calculation. Fortunately, several inexpensive versions of XRD analysis software do exist though they may not be as "user friendly" as commercial ones.
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