Condensed Matter Physics, 2007, vol. 10, No. 2(50), p. 269287, English
DOI:10.5488/CMP.10.2.269

Title: Theoretical investigations of thermodynamic properties of partially deuterated K(H1-xDx)2PO4 ferroelectrics
Author(s):
  R.R.Levitskii (Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, 1 Sventsitsky Str., 79011 Lviv, Ukraine) ,
  B.M.Lisnii (Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, 1 Sventsitsky Str., 79011 Lviv, Ukraine) ,
  A.Ya.Andrusyk (Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, 1 Sventsitsky Str., 79011 Lviv, Ukraine)

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.

Key words: KDP, proton ordering model, four-particle cluster approximation, mean crystal approximation
PACS: 77.22.Ch,77.80.Bh, 77.84.Fa


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