New paradigm for configurational entropy in glass-forming systems

Abstract

Abstract We show that on cooling towards glass transition configurational entropy exhibits more significant changes than predicted by classic relation. A universal formula according to Kauzmann temperature $${T}_{K}$$ T K is given: $$S={S}_{0}{t}^{n}$$ S = S 0 t n , where $$t=\left(T-{T}_{K}\right)/T$$ t = T - T K / T . The exponent $$n$$ n is hypothetically linked to dominated local symmetry. Such a behaviour is coupled to previtreous evolution of heat capacity $$\Delta {C}_{P}^{config.}\left(T\right)=\left(nC/T\right){\left(1-{T}_{K}/T\right)}^{n-1}$$ Δ C P c o n f i g . T = n C / T 1 - T K / T n - 1 associated with finite temperature singularity. These lead to generalised VFT relation, for which the basic equation is retrieved. For many glass-formers, basic VFT equation may have only an effective meaning. A universal-like reliability of the Stickel operator analysis for detecting dynamic crossover phenomenon is also questioned. Notably, distortions-sensitive and derivative-based analysis focused on previtreous changes of configurational entropy and heat capacity for glycerol, ethanol and liquid crystal is applied.