Theoretical investigations of thermodynamic properties of partially deuterated K(H₁₋xDx)₂PO₄ ferroelectrics

摘要

The research of thermodynamic properties of partially deuterated K(H₁₋xDx)₂PO₄ crystals was performed within the framework of proton ordering model with tunnelling within the four-particle cluster approximation for short-range interaction and within the molecular field approximation for long-range interaction. The KD₂PO₄’s model parameters were derived for the case of acceptable description of the experimental data for crystal thermodynamic characteristics. Based on the introduced procedure of deriving parameters for K(H₁₋xDx)₂PO₄ crystals, the thermodynamic and dielectric properties of these crystals were calculated and the results were compared with the experimental ones. The problem of applying the mean crystal approximation to the analysis of physical characteristics of K(H₁₋xDx)₂PO₄ crystals was discussed.