Trial lecture Flashcards
What is piezoelectricity
The appearance of an electric polarization due to mechanical stress.
Why does orthorombic structure have lower symmetry than tetragonal structure?
Because a != b (in orthorombic structure), meaning that it matters if you choose the a or the b axis in order to translate to a similar lattice point.
http://stanford.edu/~jeffjar/statmech2/intro3.html
What is the dielectric constant?
A measure of the energy storing capability of the material in the form of electric field, or in other words, the ability of the material to get polarized by the electric field (separation of oppositely charged species)
What is the relation between dielectric constant and screening?
Low epsilon means you have to get really close to see anything (ref. Debye length), i.e. large screening.
What is an electrostatic field?
A special case of an electric field, where it is bound charge that creates the electric field (for example, if domain walls in ferroelectrics are charged).
What is a typical ferroelectric domain wall thickness?
Only a few unit cells (and can be probably even sharper), meaning around 1 nm - significantly less than the typical ferromagnetic domain wall.
What is the energy per volume stored in a ferroelectric with an internal electric field?
w_e = 0.5epsilonE^2
What is the Curie temperature of BaTiO3?
120 degrees celsius
How do you pronounce BiFeO3?
Bismuth ferrite
What is, roughly, the Curie temperature of bismuth ferrite?
900 degrees celsius.
