Dielectrics- Defects Flashcards
Types of point defects
Vacancy, impurity, interstitial
Vacancy defect
Missing atom in lattice site
Impurity defect
Atom replaced by a foreign atom
Interstitial defect
Extra atom not on lattice site. Can be native or impurity
Which type of defect is less common in BaTiO3?
Interstitial atoms due to there not being much empty space between the atoms in the perovskite structure
How to compensate the vacancy of an ion
Can have a vacancy of an ion of opposite charge such that the overall charge change is 0. Can add another of the same atom from the vacancy into an interstitial position. Can change oxidation states of other ions
Which compensation scheme will be most likely to occur?
The one with the lowest energy
Kröger-Vink terminology
For recording ceramic defects. Takes form of M subscript S superscript C. M is species of defect. Can be element name, v for vacancy, e for electron, h for hole. S is defect site. Either atom name if defect on atom site or I for interstitial. C is resulting charge of defect. Each point of positive charge is one dot, each point of negative charge is one apostrophe, no charge is x.