Coupled acoustic modes in tetragonal BaTiO₃: temperature dependence

Abstract

The acoustic velocities in BaTiO₃ were measured as a function of temperature up to 350°C by means of Brillouin scattering. The behavior of the transverse acoustic phonons propagating along [001], so called coupled phonon, in tetragonal BaTiO₃ was discussed in relation to that of the spontaneous polarization on the basis of the piezoelectric equation. The scattering intensity of the coupled phonon mode is related to an effective photoelastic constant including the electro-optic coefficient through the piezoelectric interaction.

Key Words:

• BaTiO₃
• Brillouin scattering
• coupled acoustic phonon
• photoelastic constant
• piezoelectric equation