82610 - concentration of vacancies can be determined from i...

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Ch.4 Imperfections in the Atomic and Ionic Arrangements (crystal defects) Intro- Basically three categories of defects in a crystal; point defects, line defects, and planar (surface) defects. 4.1 Point Defects 1. Point defects are located as a single site in a crystal laddice. They are one dimensional. a. Vacancy- When an atom or ion is missing from regular lattice site. Vacancies are present in all crystalline materials. Vacancies are present in all crystalline materials. Vacancies participate in diffusion (the movement of atoms in a crystal). The
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Unformatted text preview: concentration of vacancies can be determined from: i. C v = N v /N= e ( -Qv/Rt ) 1. Nv= Number of vacant sites 2. N= Number of lattice sites 3. Qv= Energy to and from 1 mol of vacancies 4. R= Gas Constant 5. T= abs temp in kelvin ii. Near the melting point of conecentration of vacancies can be 0.1% 2. Intersititial Defect a. An extra atom is inserted into that is not usually a lattice point. Intersitial atoms are typically small and just “squeeze” in...
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