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Crystals and Their Structure

Crystals and Their Structure. Unit Cells in the Cubic Crystal System. Simple Cubic. Body - Centered Cubic. Face - Centered Cubic. Cubic Closest Packing of Frozen Argon. Cubic Closest Packing of Frozen Methane. Coordination Number. Counting Cell Occupancy. Volume of the Unit Cell. L. r.

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Crystals and Their Structure

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  1. Crystals and Their Structure

  2. Unit Cells in the Cubic Crystal System

  3. Simple Cubic

  4. Body - Centered Cubic

  5. Face - Centered Cubic

  6. Cubic Closest Packing of Frozen Argon

  7. Cubic Closest Packing of Frozen Methane

  8. Coordination Number

  9. Counting Cell Occupancy

  10. Volume of the Unit Cell L r r is the radius of an atom in the unit cell The volume of the unit cell is L3 But how do you get L? The Pythagorean Theorem, of course!

  11. r r r r Volume of the Unit Cell L L

  12. r r r r Calculating Packing Efficiency L L Cell occupancy = 4 Packing efficiency is the ratio of the space occupied in the unit cell to the volume of the unit cell

  13. Sodium Chloride

  14. Crystalline and Amorphous Silicon Dioxide Cristobalite, one of the crystalline forms of silicon dioxide, shows cubic closest packing. A glass made from silicon dioxide shows the amorphous disoriented structure.

  15. STM of Silicon

  16. STM of Gold www.ieap.uni-kiel.de/surface/ag-berndt/ mikro/images/stm.gif 3/27/02

  17. STM Images Xe atoms on Ni substrate www.almaden.ibm.com/vis/stm/atomo.html 3/27/02

  18. STM Images Carbon monoxide on Pt www.almaden.ibm.com/vis/stm/atomo.html 3/27/02

  19. STM Images Fe corral on Cu substrate www.almaden.ibm.com/vis/stm/atomo.html 3/27/02

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