Density Scaling in Ionic Glass Formers Controlled by Grotthuss Conduction.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Physical Chemistry

Background:

• Ionic glass-formers are crucial for understanding complex material behaviors.
• Proton transport in glasses is vital for applications like fuel cells.
• Carvedilol dihydrogen phosphate (CP) exhibits unique charge transport properties.

Purpose of the Study:

• To investigate charge transport in CP under varying thermodynamic conditions (temperature, pressure, volume).
• To explore the applicability of density scaling and thermodynamic scaling concepts.
• To understand the liquid-glass transition dynamics in CP.

Main Methods:

• Experimental measurements of conductivity and relaxation times at various T, P, V conditions.
• Analysis using density scaling and thermodynamic scaling formalisms.
• Application of the fictive temperature concept to unify scaling behaviors.

Main Results:

• CP exhibits superprotonic properties, confirmed by the Walden rule.
• Isobaric conductivity data in volume formalism showed no clear liquid-glass transition.
• Isochronal analysis revealed distinct relaxation dynamics above and below the glass transition temperature (T_g).
• Thermodynamic scaling was observed in both supercooled liquid and glassy regimes, but with different exponents (γ^SL = 1.12; γ^G = 0.48).
• Introduction of fictive temperature (T_f) enabled universal scaling with a single γ parameter for Grotthuss-type conductors.

Conclusions:

• The study highlights the complex charge transport behavior in CP.
• Density and thermodynamic scaling are powerful tools for analyzing transport properties in ionic glasses.
• The fictive temperature concept successfully unifies the scaling behavior of glassy and supercooled Grotthuss-type conductors.