CH 101 notes 10-10

CH 101 notes 10-10 - Chapter 8: Solid Materials Structure...

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Chapter 8: Solid Materials crystalline amorphous Structure of solids Crystal lattice : pattern of the ordered array Section 8.0 X O X O X O X O O X O X O X O X X O X O X O X O O X O X O X O X X O O X X O X O O X X X O X O X X O X O O O X O X X X O X X X O Local order Long range order Unit cell : simplest portion that shows the pattern Structure of solids : simplest portion that shows the pattern (repeat unit) Cubic unit cells sc simple cubic lattice sites corners bcc Body-centered cubic lattice sites corners & center fcc Face-centered cubic lattice sites corners & faces Section 8.1 simple cubic (primitive) lattice sites: corners Atoms/cell = 8 corner atoms x 1/8 ownership Atoms/cell = 1 Atom Packing Efficiency = 52 % Very light material. Not dense. Example: Polonium Coordination Number = 6 Section 8.1-8.5 Body-centered cubic lattice sites : Corners & Center Atoms/cell = 8 corner atoms x 1/8 ownership + 1 central atom at full ownership Atoms/cell = 2 Atoms Packing Efficiency = 68 % More dense than SCC Example: iron Coordination Number = 8 Section 8.1-8.5 Face-centered cubic lattice sites: Corners & Faces Atoms/cell = 8 corner atoms x 1/8 ownership + 6 face atoms x 1/2 ownership Atoms/cell = 4 Atoms Packing Efficiency = 74 % Most Dense cubic cell Example: iron in stainless steel Coordination Number = 12 Section 8.1-8.5 Unit Cell Ownership of Atoms 1 center atom at full ownership = 1 atom Section 8.3 A cube has 1 center It takes 1 cube to “own” a center atom
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Unit Cell Ownership of Atoms 6 face atoms at 1/2 ownership = 3 atoms Section 8.3 A cube has 6 faces It takes 2 cubes to “own” a face atom Unit Cell Ownership of Atoms
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This note was uploaded on 06/08/2008 for the course CH 101 taught by Professor Bigham during the Fall '08 term at N.C. State.

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CH 101 notes 10-10 - Chapter 8: Solid Materials Structure...

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