09-18-Lecture

09-18-Lecture - 1 SOLIDS IMPER FECT IONS ENGR 213 DEFECTS...

Info iconThis preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 1 SOLIDS IMPER FECT IONS ENGR 213 DEFECTS no perfect crystals all have defects = lattice irregularity point defects 0.1nm line defects (dislocations) 10nm interfacial / area defects 0.01 - 0.1 m volume defects 0.01 - 1mm POINT DEFECTS IN METALS Interstitial rare extra atom space is smaller than atom lowers stability of structure Vacancies Common hole in lattice POINT DEFECTS IN METALS Nobodys home! Fives a crowd! VACANCIES IN METALS exist due to 2nd law of thermodynamics @ equilibrium, the number of vacancies is given by Q v = energy to remove atom from lattice site by breaking bonds w/ nearest neighbors T = temperature in deg Kelvin k = Boltzmanns constant (8.6E-5 eV/atom-K) kT Q v v Ne N-= POINT DEFECTS IN CERAMICS anions & cations vacancies & interstitials for each ion species anion interstitials rare due to size electroneutrality must be maintained charge balance of anions and cations stoichiometric Frenkel defect cation vacancy + cation interstitial Stoichiometric Schottky defect cation vacancy + anion vacancy stoichiometric TWO POINT DEFECTS IN CERAMICS Grass looks greener!...
View Full Document

This note was uploaded on 03/26/2008 for the course ENGR 213 taught by Professor Dr.stubbs during the Fall '04 term at Texas A&M.

Page1 / 24

09-18-Lecture - 1 SOLIDS IMPER FECT IONS ENGR 213 DEFECTS...

This preview shows document pages 1 - 8. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online