The Röntgen Radiation and its application in studies of ... - Mansic

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7. Applications of XRD The study of the X radiations has played a vital part in physics, especially for the development of the advanced material characterization. As a mean of research, the X radiations have allowed the scientists to experimentally confirm structural properties of materials. By using the diffraction method, the crystalline substances can be identified and their structure determined. The method can also be applied for powders that do not posses a crystalline structure, but they are amorphous. By these means, chemical compounds can be identified and the size of the ultramicroscopic particles can be established. Besides the applications from physics, chemistry, mineralogy, metalurgy and biology, which mainly base on effect of diffraction another feature of X-rays – its possibility to go thorough materials - is used in industry. Especially it is applied for the non-destructive reflecting of some metallic alloys. Some tests are being done in different phases of the production cycle and the defects are eliminated. The soft X-rays are used for establishing the authenticity of some works of art or for the restoration of paintings. In medicine, the radiographs and the fluoroscopes are used for diagnosis. The computerized machine, the axial tomograph (CAT or CT scanner) was invented in 1972 by the electronics engineer Godfrey Hounsfield and came into use on large scale after 1979. Despite of structural studies, X-rays are used for chemical analysis of materials. An X-ray source is used to irradiate the specimen. It causes emission (or fluoresce) of characteristic X-rays from the elements presented in a specimen. A detection system (wavelength dispersive) is used to measure the peaks of the emitted X-rays for qual/quant measurements of the elements and their amounts. However, the main part of the X-ray application is structural investigation, that’s several technique and methods are applied for single crystals as well as polycrystalline materials. Some of them are discussed as follow: -To identify crystalline phases and orientation A condition in which the distribution of grains orientation is non-random. Figure 18. Preferred Orientation in a powder sample The first evidence of preferentially oriented grains in studied materials are anomalies in diffraction peak intensity. Example is shown in Figure 18, which compare X-ray diffraction patterns collected for material with randomly oriented grains (blue) and sample revealing texture. Preferred orientation of grains can introduce anisotropy of material properties. In case of single crystal Laue Physics of Advanced Materials Winter School 2008 14
technique is used for determination of its orientation (Figure 19). From stereographic projection appropriate crystallographic directions can be find. Figure 19. Basics of the Laue method for single crystals studies -To determine structural data: lattice parameters, strain, grain size, phase composition, preferred orientation, order-disorder transformation, and thermal expansion. As an example we mention the use of X-ray analysis to make phase and structure analysis on the polycrystalline Cd0,5Ge0,5Cr2Se4 and CdCr1,9Ge0,075Se4 compounds. Both compounds crystallized in cubic, normal spinel structure, Fd3m [11]. Another example is phase identification in multi-phase sample - the oxidation states of copper applied for roof covering (Figure 20). The major phase is quartz (red), also a significant amount of Cu (green). Perhaps some Cu2O (blue) and other unidentified phases are also present. Figure 20. The phases of the material -To measure the thickness of thin films and multi-layers Physics of Advanced Materials Winter School 2008 15
Page 1 and 2: The Röntgen Radiation and its appl
Page 3 and 4: The next improvement was introduced
Page 5 and 6: 2. The production of X-rays The X r
Page 7 and 8: Due to the fact that Kβ and Kα2 a
Page 9 and 10: Crystal net is built from planes of
Page 11 and 12: Figure 10. A Modern Automated X-ray
Page 13: a) b) Intensity 20 40 60 80 100 120
Page 17 and 18: In te ns it y Temperature 0 C 2θ F

The Röntgen Radiation and its application in studies of ... - Mansic

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