Lecture01

Lecture01 - Chapter 1: Crystal Structure The Nobel Booby...

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Chapter 1: Crystal Structure The Nobel “Booby” Prize! See the “Ig Nobel” Prize discussed at: http://improbable.com/ig/
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Phases of Matter “Condensed Matter” actually includes both of these. We’ll focus on Solids ! Gases Matter Liquids & Liquid Crystals Solids
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Gases Gases have atoms or molecules that do not bond to one another in a range of pressure, temperature and volume. These molecules haven’t any particular order and move freely within a container.
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4 Similar to gases, L iquids have no atomic/molecular order and they assume the shape of the containers. Applying low levels of thermal energy can easily break the existing weak bonds. Liquid C rystals have mobile molecules, but a type of long range order can exist; the molecules have a permanent dipole. Applying an electric field rotates the dipole and establishes order within the collection of molecules. Liquids & Liquid Crystals
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Solids consist of atoms or molecules undergoing thermal motion about their equilibrium positions, which are at fixed point s in space. Solids can be crystalline, polycrstalline, or amorphous. Solids have stronger interatomic bonds than liquids. So, Solids require more energy to break the interatomic bonds than liquids . Solids
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Crystal Structure Topics 1. Periodic Arrays of Atoms 2. Fundamental Types of Lattices 3. Index System for Crystal Planes 4. Simple Crystal Structures 5. Direct Imaging of Crystal Structure 6. Non-ideal Crystal Structures 7. Crystal Structure Data
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Objectives At the end of this Chapter, you should : 1. Be able to identify a unit cell in a symmetrical pattern. 2. Know that there are 7 possible unit cell shapes 3. Be able to define cubic, tetragonal, orthorhombic and hexagonal unit cell shapes
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Periodic Arrays of Atoms Experimental evidence of periodic structures. (See Fig. 1 .) The external appearance of crystals gives some clues to this. Fig. 1 shows that when a crystal is cleaved, we can see that it is built up of identical “building blocks”. Further, the early crystallographers noted that the index numbers that define plane orientations are exact integers. Cleaving a crystal
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Elementary Crystallography Solıd Materıals Crystallıne Polycrystallıne Amorphous (Non-Crystalline) Single Crystal
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Single crystal Polycrystalline Amorphous Each type is characterized by the size of the ordered region within the material. An ordered region is a spatial volume in which atoms or
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Lecture01 - Chapter 1: Crystal Structure The Nobel Booby...

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