Title: Ferroelectric-antiferroelectric mixed systems. Equation of state, thermodynamic functions
Author(s):

	N.A.Korynevskii (Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, 1 Svientsitskii Str., Lviv 79011, Ukraine; Institute of Physics, University of Szczecin, 15 Wielkopolska Str., 70451 Szczecin, Poland) ,
	V.B.Solovyan (Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, 1 Svientsitskii Str., Lviv 79011, Ukraine)

The problem of equation of state for ferroelectric-antiferroelectric mixed systems in the whole region of a concentration change
(0≤n≤1) is discussed. The main peculiarity of the presented model turns out to be the possibility for the site dipole momentum to be oriented ferroelectrically in z-direction and antiferroelectrically in x-direction. Such a situation takes place in mixed compounds of KDP type. The different phases (ferro-, antiferro-, paraelectric, dipole glass and some combinations of them) have been found and analyzed.

Key words: ferroelectrics and antiferroelectrics, mixed systems, equation of state
PACS: 75.10.Hk, 77.22.Ch, 77.84.F