On the History and Recent Applications of Hyperfree Energy Describing Thermodynamics of Mobile Components in Partly Open Ceramic Systems

Abstract

Nonstoichiometric oxides form a new chapter in tailored materials. Founding and construction of thermodynamic functions related to solid (geologic) materials is traced showing interactions between Czech Professor F. Wald and Russians R.S. Kurnakov and D.S. Korzhinskiy in the early definition of phases and characterization of partly open systems. Development of thermodynamic concepts regarding solid-state description is reviewed. For the associated definition of a mobile component the hyperfree energy was invented and recently applied on several systems. A novel term plutability is put forward as a measure of material susceptibility towards free component uptake as a result of varying predictors such as temperature, pressure and activity. Ehrenfest-like equations involving the changes of plutabilities were derived.