Two Phonon Interaction Process in the Ferroelectric Ceramics (Pb_{1 − 3X/2}La_X□_X/2)(Zr_0.95 Ti_0.05)O₃ with 1 ≤ X ≤ 8 at %

Abstract

Results of Raman spectroscopy study of the ceramics (Pb_{1 − 3X/2}La _X □ _X/2 ) (Zr_0.95Ti_0.05)O_3,denoted hereafter PLZT-x/95/5, with particular focus on the low frequency phonon dynamics are presented. The dynamic process that governs the low frequency acoustic phonons is linked to the process of the excited electronic states in Cr³⁺ ions due to the strong crystalline field in the lattice environment created by the lanthanum doping. Their presence may explain the Raman activation, in the ferroelectric phase, of two theoretically predicted zone-boundary acoustic phonons at 29 cm⁻¹ and 100 cm⁻¹.

Keywords:

• Raman spectroscopy
• phase transition
• two-phonon process
• excited states
• ferroelectric ceramics