Anomalies of nonlinear light scattering near ferroelectric phase transition point in crystals

Abstract

The temperature dependencies of Hyper-Rayleigh light scattering intensity for a number of crystals (BaTiO₃, Pb₅Ge₃O₁₁, K₂ZnCl₄, Li₂Ge₇O₁₅) near ferroelectric phase transition points are presented. Copper vapour and YAG:Nd³⁺ impulsive lasers were used for nonlinear light scattering exciting. The sharp increase of Hyper-Rayleigh scattering intensity, i.e. so called Hyperopalescence effect near ferroelectric phase transition points has been revealed. Anomalies in temperature dependency of nonlinear light scattering intensity depended from the type of ferroelectric phase transition and defects. The explanation of Hyperopalescence effect was proposed on the base of instability and soft mode behaviour of crystalline lattice near ferroelectric phase transition point.

Keywords:

• Hyperopalescence
• anomalies
• scattering
• mode
• transition
• increase