Structural relaxation and quasi-elastic light scattering in glass: Approach by ferroelectric and ion-conducting phases

Inelastic light scattering has been utilized for examining the structure of glass and its relaxation. However, the quasi-elastic-light-scattering (QLS) phenomenon has not been addressed in much detail. In this study, we observed pronounced QLS-intensity variations in two temperature domains-supercooled liquid (SCL) state (α-relaxation regime) and below the glass-transition temperature (β-relaxation regime)-in niobium-oxide (Nb ₂O ₅)-rich glass. These variations may be interpreted on the basis of the concept of ferroelectric and ion-conducting phases. It was suggested that the observed QLS originates as a result of the polarization fluctuation of NbO ₆ units, which is due to the dynamics of the nanometric phase separation in the SCL phase (α-regime), and the fluctuation due to the migration/hopping of conductible ions that are localized in the vicinity of the NbO ₆x units (β-regime).