A theoretical study of the dielectric constant of perovskite type crystals
Barrett, John H.
Doctor of Philosophy
The dielectric properties of perovskite type crystals are of interest because some of the compounds having this crystal structure are ferroelectric. The word ferroelectric is derived by analogy with the word ferromagnetic; it means that the material has a spontaneous electric polarization just as a magnet has a spontaneous magnetic polarization. While in this country the term ferroelectric is universally used, in Europe the term seignettoelectric is often used instead. This usage stems from the fact that the first ferroelectric discovered was Seignette salt or Rochelle salt. Ferroelectric materials are of interest because they are piezoelectric, they have high dielectric constants, and their dielectric constants are strongly temperature dependent. These properties lead to many applications. A study of the theory of ferroelectrics should be useful in utilizing their properties and in discovering new ferroelectrics.