Theoretical study of refractive indices, birefringence and spontaneous polarization of KNbO₃ in the tetragonal phase

Abstract

The microscopic mechanism of refractive indices, birefringence and spontaneous polarization of KNbO₃ in the tetragonal phase is discussed by using a microscopic model. In this model, we have taking into account of a quantum method based upon the orbital approximation and the dipole-dipole interaction due to the local field acting on the constituent ions. It is found that the electronic polarizabilities play a major role in these calculations.

Keywords:

• KNbO₃
• refractive index
• birefringence
• spontaneous polarization
• orbital approximation
• dipole-dipole interaction