Slow relaxation processes in molten ZnCl₂ studied by photon correlation spectroscopy

Abstract

Photon-correlation spectra of molten zinc chloride have been investigated as a function of temperature in the range 553-713 K. All isotropic spectra show a single distribution of relaxation times, characterized by an average relaxation time ⟨τ⟩_is and a width β_is. The results are successfully interpreted within the framework of a “bond-lattice” model, indicating that fluctuations in the dielectric constant originate from configurational relaxation phenomena. Furthermore, the occurrence in the anisotropic scattering of two distinct distributions of relaxation times allows us to relate the faster one to the transport parameter n _s and the slower one to very-longtime diffusive motion. Finally, the presence of an anomalous relaxation across the melting point supports other experimental evidence that visco-elastic and transverse effects take place in the system.