Condensed Matter Physics, 2017, vol. 20, No. 4, 43707

Title: Influence of hydrostatic pressure on thermodynamic characteristics of NH3CH2COOH·H2PO3 type ferroelectric materials
Author(s):
  I.R. Zachek (Lviv Polytechnic National University, 12 Bandera St., 79013 Lviv, Ukraine) ,
  R.R. Levitskii (Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, 1 Svientsitskii St., 79011 Lviv, Ukraine) ,
  A.S. Vdovych (Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, 1 Svientsitskii St., 79011 Lviv, Ukraine)

The model of NH3CH2COOH·H2PO3, modified by taking into account of piezoelectric coupling between ordering structure elements and the strains εi, εj, is used for investigation of the effects, that appears under external pressures. Within two-particle cluster approximation the components of polarization vector and static dielectric permittivity tensor of the mechanically clamped and free crystals, their piezoelectric and thermal characteristics are calculated. The influence of hydrostatic pressure on the phase transition and calculated physical characteristics of the crystal is studied. A good quantitative description of the experimental data for these crystals is obtained.

Key words: ferroelectrics, phase transition, dielectric permittivity, piezomoduli, hydrostatic pressures
PACS: 77.22.-d, 77.22.Ch, 77.22.Ej, 77.65.-j, 77.80.Bh


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