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alliedacademies
Materials Science and Nanotechnology | Volume 2
May 21-22, 2018 | New York, USA
International Conference on
Nanoscience & Technology
The general increase in the requirements for functional
opportunities of different devices has sharply increased
the demands for their elemental base. Natural materials
no longer satisfy the growing technological and operational
requirements due to the limited range of operating
parameters, randomness of their characteristics and the
absence of opportunities for changing functional parameters.
Artificial nanomaterials with controlled properties, based
on the influence of nanoscale effects on the properties of
materials, one of them is ferroelectric nanocomposites,
fit better for these purposes. An important characteristic
for practical application of these materials is temperature
range, where ferroelectric properties are observed in the
researched composites. Factors reducing their Curie point
TC are the correlation effects as well as the depolarizing
fields arising near the surface of the ferroelectric inclusions.
The present work calculates depolarizing fields arising near
the boundaries of a spherical ferroelectric inclusion in an
isotropic dielectric environment and evaluates the effect
of these fields, and screening effects on the Curie point in
the composites. The studies of depolarizing field effects on
the transition temperature in ferroelectric composites, with
spherical ferroelectric inclusions embedded in the dielectric
matrix, demonstrate that, in the absence of screening effects,
the decrease of the Curie point in composites compared with
bulk materials is determined by the ratio of the ferroelectric
inclusion Curie constant to the permittivity of the matrix.
The TC shift in these composites with screening is reduced
by multiplying the above value by a decreasing factor equal
to the ratio of the screening length to the radius of the
ferroelectric inclusion. The authors suppose that the example
of such material can be a composite of nanocrystalline
cellulose with ferroelectric sodium nitrite, for which the
Curie point is displaced approximately 40 degrees lower
on the temperature scale relative to bulk sodium nitrite.
Another demonstration of depolarizing fields and screening
effects’ influence is the behavior of the mixture composite
triglycine sulfate and silica.
Speaker Biography
Alexander Sidorkin, doctor of physical and mathematical sciences, professor of the
department of experimental Physics, Voronezh State University, Russia. He is the
author of over 200 scientific works, including several books. A.S. Sidorkin is a head
of several scientific grants, participant of numerous scientific conferences, member
of Scientific Council of Russian Academy of Sciences on Dielectric and Ferroelectrics,
Honored Worker of Higher Professional Education of the Russian Federation.
e:
Influence of depolarizing fields and screening effects on phase transitions in ferroelectric composites
Alexander Sidorkin
Voronezh State University, Russia