Dielectrics- Defects

Question 1

Types of point defects

Answer 1

Vacancy, impurity, interstitial

Question 2

Vacancy defect

Answer 2

Missing atom in lattice site

Question 3

Impurity defect

Answer 3

Atom replaced by a foreign atom

Question 4

Interstitial defect

Answer 4

Extra atom not on lattice site. Can be native or impurity

Question 5

Which type of defect is less common in BaTiO3?

Answer 5

Interstitial atoms due to there not being much empty space between the atoms in the perovskite structure

Question 6

How to compensate the vacancy of an ion

Answer 6

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

Question 7

Which compensation scheme will be most likely to occur?

Answer 7

The one with the lowest energy

Question 8

Kröger-Vink terminology

Answer 8

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.