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Immobolization of radioactive waste in ceramic based hosts: Radioactive waste Immobolization von Bohre, Ashish (eBook)

  • Erscheinungsdatum: 01.02.2014
  • Verlag: Anchor Academic Publishing
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Immobolization of radioactive waste in ceramic based hosts: Radioactive waste Immobolization

Ceramic materials have found numerous applications in science, technology and industry as mentioned earlier. One of the recent applications of titania and zirconia based ceramic precursors is in immobilization and solidification of radioactive isotopes in waste effluents coming out of nuclear establishments and power plants. Due to long term stability and integrity of the ceramic waste forms of high and intermediate level nuclear waste, several countries have now switched over from 'glass technology' to 'ceramic technology' of radwaste management. These and many more applications make ceramics materials an interesting area of research and engineering sciences. The book is particularly aimed at scientific and technical staff in the nuclear and waste management industries in addition to universities and research organizations active in these areas. It will also appeal to a wider audience with interests in environmental issues and will be of benefit to anyone who requires background information on radioactive issues connected with nuclear energy or defense processes, or hazardous waste sources, properties and treatments using crystallographic methods. Dr. Ashish Bohre obtains his Ph.D. degree from Dr. Harisingh Gour Central University Sagar, in 2012. Presently he is working as a post-doctoral research fellow in Delhi University. Dr. Bohre is an author of several research articles and books of internati


    Format: PDF
    Kopierschutz: none
    Seitenzahl: 212
    Erscheinungsdatum: 01.02.2014
    Sprache: Englisch
    ISBN: 9783954896691
    Verlag: Anchor Academic Publishing
    Größe: 12180kBytes
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Immobolization of radioactive waste in ceramic based hosts: Radioactive waste Immobolization

Text Sample: Chapter 2, Crystal Structure RefinementAnd instrumentation 2.1, Powder Diffraction method: A major emphasis of materials science is in understanding the elemental compositions and corresponding atomic structures present in materials of interest. This knowledge confirms a material's purity and suitability for use, and allows explanation for ist properties and performance. Just as chemical elements form a plethora of compounds, so a compound may pack in different arrays to form a variety of distinct crystal structures (known as polymorphs or phases). Elemental composition and physical characteristics such as color and hardness might differentiate phases when encountered in pure form. When in mixtures or reacted with other materials, identification of phases based on physical characteristics or elemental composition can quickly become impossible. Powder diffraction has been the staple analytical tool for chemists and materials scientists for more than 50 years. Powder diffraction is a tool to identify and characterize materials by analyzing the radiation scattering produced when the materials are illuminated with X-rays or neutrons. The patterns formed by the scattered radiation provide an abundance of information from simple fingerprinting to complex structural analysis. X-ray powder diffraction is a powerful non-destructive testing method for determining a range of physical and chemical characteristics of materials. It is widely used in all fields of science and technology [1]. The applications include phase analysis, i.e. the type and quantities of phases present in the sample, the crystallographic unit cell and crystal structure, crystallographic texture, crystalline size, macro-stress and micro strain and also electron radial distribution functions. The usefulness of powder diffraction ranges throughout all areas where materials occur in the crystalline solid state. Uses for powder diffraction are found within the following fields and beyond: Natural Sciences; Materials Science; Pharmaceuticals; Geology and Petrochemicals; Engineering; Metallurgy; Forensics; Conservation and Archaeology. The term 'powder', as used in powder diffraction, does not strictly correspond to the usual sense in the word in common language. In powder diffraction the specimen can be a 'solid substance divided into very small particles' But it can also be a solid block for example of metal, ceramic, polymer, glass or even a thin film or a liquid. The reason for this is that the important parameters for defining the concept of a powder for a diffraction experiment are the number and size of the individual crystallites that form the specimen, and not their degree of accretion [2]. An 'ideal' powder for a diffraction experiment consists of a large number of small, randomly oriented crystallites (coherently diffracting crystalline domains). If the number is sufficiently large, there are always enough crystallites in any diffracting orientation to give reproducible diffraction patterns. 2.2, Determination of crystal structure: Atomic structure is the most important piece of information about crystalline solids: just from the knowledge of topology of the structure, a precise structural model and many physical properties of crystals can be calculated with state of-the-art quantum-mechanical methods. 'The ability to determine crystal structures directly from powder diffraction data promises to open up many new avenues of structural science. Many important materials cannot be prepared as single crystals of appropriate size and quality for conventional single crystal diffraction studies, nor indeed for the emerging synchrotron-based microcrystal diffraction techniques. In such cases, structure determination from powder diffraction data may represent the only viable approach for obtaining an understanding of the structural properties of the material of interest [3]'. However, it is important to recognize that structure determination from powder diff

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