CIVE265 Lecture Notes - Lecture 6: Intermetallic, Coordination Number, Crystal Twinning

• School: University of Waterloo
• Department: Civil Engineering
• Course: CIVE265
• Professor: John Straube

Document Summary

Imperfections: defects: crystalline defect: lattice irregularity having one or more of its dimensions on the order of an atomic diameter; classification of crystalline imperfections frequently made according to the geometry or dimensionality of defect. Point defects (associated with one or two atomic positions), linear defects (one dimensional), interfacial defects (boundaries, two dimensional) Occur due to thermal vibration of atoms above absolute zero. 4. 2 vacancies and self-interstitials: vacancy: vacant lattice site, one normally occupied but from which an atom is missing, all crystalline solids contain vacancies; presence of vacancies increases the entropy. Self-interstitial: an atom from the crystal that is crowded into an interstitial site- a small void space that under ordinary circumstances is not occupied. Introduces relatively large distortions in the surrounding lattice because the atom is substantially larger than the interstitial position in which it is situated: formation is highly not probable; exists in very small that are significantly than vacancies.