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Unformatted text preview: 1 MEMS 1054 Materials Science 1 or Structure of Crystals and Diffraction Week 46  Diffraction 1 Professor Jörg Wiezorek, PhD, Materials Science and Metallurgy, University of Cambridge, UK, 1994. Meets in room G37 BEH, Mon/Wed/Fri, 11:50PM Week 46 A) Crystal Structure Studies by Xray Diffraction; What is Diffraction? What is a diffraction pattern? What are X rays? How do we make Xrays? What does an emission spectrum from a typical Xray tube look like? How do Xrays interact with atoms in crystals? Paradigms of Diffraction from Crystals B) Diffraction from Crystals: Geometry, The Bragg Law (Equation), Laue Conditions What is Diffraction? The Geometrically necessary condition for diffraction from a crystal lattice  The Bragg Law! ; Examine the Bragg equation and idealized diffraction patterns; Xray diffraction patterns from Single Crystals, textured polycrystals, Powder (random texture); C) Diffracted Intensities: The Structure Factor D) The Reciprocal Lattice and the Laue Equation 0) Reciprocal Lattice / Reciprocal Space Lattice / Space Lattice 2 Reciprocal Space Lattice; Reciprocal Lattice; Reciprocal Space; Phase Space; kspace Try the Uplink Here I present to you a useful hyperlink for the exploration of concepts related to basic ideas regarding Xrays, Reciprocal Space Lattices and their relation to diffraction from Crystals; have a look and work on the control questions – http://www.doitpoms.ac.uk/tlplib/reciprocal_lattice/index.php http://www.doitpoms.ac.uk/tlplib/reciprocal_lattice/index.php 3 Reciprocal Space Lattice and Crystals and Diffraction from Crystals 3 Reciprocal Space Lattice and Crystals and Diffraction from Crystals 4 Diffraction in Reciprocal Space! Reciprocal Lattice of the Crystal and Diffraction  Ewald Sphere Construction; 1/ λ = R E The REFLECTING SPHERE (elastic sphere, Ewald Sphere) and the LIMITING SPHER Limiting Sphere … R LS = 2/ λ = 2 R ES Polarized Light Micrograph, close packed Metal polycrystal (after Guy and Hren) Grains in a Polycrystalline Aggregate are individual Crystals of different orientations joined across their mutually shared grain boundaries;...
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This note was uploaded on 01/07/2011 for the course MEMS Mems1054 taught by Professor Wiezorek during the Fall '10 term at Pittsburgh.
 Fall '10
 Wiezorek

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