158 research outputs found
The effect of hydrostatic pressure on thermodynamic characteristics of NHCHCOOHHPO type ferroelectric materials
The model of NHCHCOOHHPO, modified by taking into
account the piezoelectric coupling between the ordering structure elements and
the strains , , is used for investigation of the
effects that appear 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 effect of
hydrostatic pressure on the phase transition and the calculated physical
characteristics of the crystal is studied. A good quantitative description of
experimental data for these crystals is obtained.Comment: 14 pages, 15 figure
Deformation effects in glycinium phosphite ferroelectric
To study the effects appearing under mechanical stresses, we have used the
model of glycinium phosphite ferroelectric, modified by taking into account the
piezoelectric coupling of ordering structure elements with lattice strains. In
the frames of two-particle cluster approximation, the components of
polarization vector and static dielectric permittivity tensor of the crystal,
as well as its piezoelectric and thermal characteristics are calculated.
Influence of shear stresses, hydrostatic and uniaxial pressures on the phase
transition and physical characteristics of the crystal is studied.Comment: 17 pages, 20 figure
Electrocaloric effect in KHPO family crystals
The proton ordering model for the KHPO type ferroelectrics is
modified by taking into account the dependence of the effective dipole moments
on the proton ordering parameter. Within the four-particle cluster
approximation we calculate the crystal polarization and explore the
electrocaloric effect. Smearing of the ferroelectric phase transition by a
longitudinal electric field is described. A good agreement with experiment is
obtained.Comment: 10 pages, 6 figures; this article is a shortened version of
arXiv:1405.1327 published in Condensed Matter Physic
Statistical theory of thermodynamic and dynamic properties of the RbHSO ferroelectrics
Within the modified four-sublattice model of RbHSO with taking into
account the piezoelectric coupling to the strains ,
, , and , the polarization
components, static and dynamic dielectric permittivity of clamped and free
crystal are calculated in the mean field approximation. At the proper choice of
the values of the theory parameters, a satisfactory quantitative description of
the available experimental data is obtained.Comment: 16 pages, 15 figure
Thermodynamic and dynamic dielectric properties of one-dimensional hydrogen bonded ferroelectric of PbHPO-type
Within the modified model of proton ordering of one-dimensional ferroelectric
having hydrogen bonds of PbHPO-type, their thermodynamic and dynamic
characteristics are studied and calculated taking into account the linear (by
crystal deformations () and )
contributions into the energy of a proton system but without taking into
account the tunneling in the two-particle cluster approximation. There has been
obtained a good quantitative description of the temperature dependence of
polarization, static dielectric permittivity, heat capacity and frequency
dependence of dynamic dielectric permittivity at different temperatures for
PbHPO and PbHDO crystals.Comment: 12 pages, 7 figure
Influence of electric fields on dielectric properties of GPI ferroelectric
Using modified microscopic model of GPI by taking into account the
piezoelectric coupling with strains in the frames of
two-particle cluster approximation, the components of polarization vector and
static dielectric permittivity tensor of the crystal at applying the external
transverse electric fields and are calculated. An analysis of the
influence of these fields on thermodynamic characteristics of GPI is carried
out. A satisfactory quantitative description of the available experimental data
for these characteristics has been obtained at a proper choice of the model
parameters.Comment: 17 pages, 17 figure
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