Depolarized light-scattering measurements have revealed the dynamics of CaKNO3 and salol near their liquid-glass transition temperatures in the frequency range of ∼ 0.2 GHz to ∼ 4 THz. The two-step relaxation process predicted by the mode coupling theory was observed in the supercooled liquid near Tc. Idealized mode coupling theory analysis for the β-relaxation region provided reasonable agreement with the scaling predictions. The crossover temperature was identified from both above and below Tc. However, systematic differences between the experimental data and the idealized theoretical β-spectra were observed at low frequencies for temperatures near and below Tc. An extended mode coupling theory analysis, which includes the phonon-assisted hopping transport, provided a good description of the complete experimental β-spectra. The hopping rate was quantitatively estimated from the analysis. Transition regions and trajectories were found in the temperature-hopping rate plane.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Condensed Matter Physics
- Materials Chemistry