Theortical study of refractive indices, birefringence and spontaneous polarization of KNbO_3 in the tetragonal phase

摘要

The microscopic mechanism of refractive indices,birefringence and spontaneous polarization of KNbO_3 in thetetragonal phase is discussed by using a microscopic model. In thismodel, we have taking into account of a quantum method basedupon the orbital approximation and the dipole—dipole interactiondue to the local field acting on the constituent ions. It is found thatthe electronic polarizabilities play a major role in these calculations.