Dispersion of the birefringence in (CH₁₂H₂₅NH₃)₂ZnCl₄ and (C₁₂H₂₅NH₃)₂ZnCl₄: Co around their isotropic points

Abstract

The optical dispersion of (C₁₂H₂₅NH₃)₂ZnCl₄ and (C₁₂H₂₅NH₃)₂ZnCl₄: Co is investigated by means of birefringence and optical absorption measurements in the temperature region around their isotropic points. The birefringence dispersion is analyzed in terms of a simple oscillator model based on the absorption band structure of both materials. A fairly good agreement is found between the thermal behaviour of the adjustable parameters of the oscillator model and the temperature dependence of the absorption spectra. The results suggest the existence of a structural phase transition at 315 K.

Key Words:

• Birefringence dispersion
• optical absorption
• layered perovskites