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Unformatted text preview: 1 CE 497 Structure of Crystals Section 5 Hui Fan 3/12/2009 3 I N TRODUCT ION: The objective of this experiment is to work with 3D crystal structure model and manipulate them to understand crystal structure. It studied two cubic crystal systems and calculated and compared atomic packing factor for them, also studies two types of vacancies and calculated and compared radius ratios for them. And finally we used the Miller Indices to describe planes of the structure. The expected error in this experiment should be less than 20%. PROCEDURE: We used hard sphere model to analyze a crystal structure. In the hard sphere model spheres represent atoms and the nearest neighbor atom touch. In this model, the arrangement of the atoms is repeating and regular. We chose a simplest repeating unit as a unit cell. The two unit cells we studied in this lab is face centered cubic (FCC) and body centered cubic (BCC). We calculated atomic Packing factor for models and compared the value with the expected one. Vacancy is an unoccupied atom site in the crystal structure. We studied two types of vacancies: octahedral and tetrahedral. In one experiment, we found the largest atom can fit into the vacancy and calculated the radius ratios. We expected that octahedral vacancy gave larger radius ratio. 4...
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 Spring '10
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