Suleyman Yilmaz

Mie Scattering in Ferroelectrics with Diffuse Phase Transitions

A computer model of light scattering from the domain structure of Pb 3 MgNb 3 O 9 (PMN) was obtained by the T-matrix method. First we discuss numerical aspects of T-matrix computations specific for ellipsoids and present results of benchmark computations for a simple ellipsoid model. Then we report results of extensive computations for poly-disperse, randomly oriented ellipsoids with the refractive index of PMN [2.15 + ki, ( k = 0.01, 0.008, 0.015)] semi-axis ratios of 1/2, 1/1.5, 1/3, 1/4 and effective size parameters ranging from 0 to 15. These computations parallel to our previous study of light scattering by poly-disperse, randomly oriented spheroids are used to compare scattering properties of two classes of particles.

Light Scattering in Ferroelastic Lead Phosphate-Type Crystals Due to Domain Structure

Ferroelastic lead phosphate-type (LP) crystals undergo a sequence of phase transition and [1]. The ferroic domain pattern depends on the spontaneous strain which can be diluted by the chemical composition. Light scattering from ferroelastic materials and its computer model was presented by T-matrix method at the structural phase transition. We discussed numerical procedure of T-matrix method and improved new computer program to calculate the scattering properties for domain structure of LP-type ferroelastic materials. Then, we report results of these calculations for polydispersive, randomly oriented spheroid with a refractive index, different semi-axis ratios and different size parameters. The calculation results are very close to our previous study of light scattering by spherical, cylindrical structures and convex particles.

Light scattering in some order-disorder type ferroelectrics due to phase transitions

Computer model of Light Scattering and Light Propagation from KDP type crystals domain structure were obtained by mean field method. We discuss numerical aspects of computations specific for slab and present results of benchmark computations for a simple slab model. Then we report results of extensive computations for poly-disperse, randomly rough 2D surface with refractive index of KDP and ADP. These computations parallel to our previous study of light scattering by poly-disperse randomly oriented spheroid and our used to compare scattering properties of the two classes of simple convex particles.

Electronic Structure and Phase Transition Effects in Some ABO 3 Materials

In this work a new theoretical study is undertaken of the electronic structure of ABO 3 materials and role of the BO 6 octahedron containing Ti, Nb, and Ta in paraelectric and ferroelectric phases. The results of this work show that, cluster calculations by the X f method (in ferroelectric and paraelectric phases) even for a minimum cluster can describe the nonlocal electronic properties of ABO 3 and can be used in discussions of the physical properties of these compounds.

Mie Scattering and Domain Structure of Ferroelectrics

A calculation procedure for obtaining the complete set of scattering coefficients and incident, scattered and internal electric fields in terms of the vector spherical harmonics for a multilayered nonlinear structure (as model of polydomain ferroelectric) is proposed by using the T-matrix method.

Investigation of anisotropic thermal conductivity of uniaxial and biaxial Gay–Berne particles with molecular dynamics simulation

In this study, we investigated uniaxial and biaxial Gay–Berne (GB) particles with the help of the molecular dynamics (MD) simulation. Anisotropic thermal conductivities of the uniaxial and biaxial GB liquid crystal molecules were calculated both in the random molecular orientation and in the molecular orientations of 0°, 45° and 90° using the Müller-Plathe method. In the uniaxial molecules, it was found that the thermal conductivity ratios between the parallel and perpendicular components for the smectic and nematic phases are about 2.2:1 and 2.8:1, respectively. As for biaxial molecules, these ratios between the parallel and perpendicular components of molecules for the smectic and nematic phases are about 3.9:1 and 3.8:1, respectively.

Molecular alignment of ferroelectric liquid crystals by polyimide thin film

25th European Crystallographic Meeting, ECM 25, İstanbul, 2009 Acta Cryst. (2009). A65, s 201 Page s 201 FA2-MS05-P01 Twin Structure of Solid Oxide Electrolytes. Taras Tataryna, Dmytro Savytskiia, Leonid Vasylechkoa, Carsten Paulmannb,c, Ulrich Bismayerc. aLviv Polytechnic National University, Lviv, Ukraine. bHASYLAB, DESY, Hamburg, Germany. cMin.Petrogr. Institut, Universität Hamburg, Hamburg, Germany. E-mail: tataryn.taras@gmail.com

Phase Transition and Energy Spectra of Some Ferroelectrics-Ferroelastics

We report the results of electronic structure calculations for several types of MoO4-clusters in the Gd2(MoO4)3 structure in ferroelectric and paraelectric phase by using cluster ab initio restricted Hartree Fock method. The results give a variational approximation to the ground state electron densities of these clusters within the framework of ab initio restricted Hartree Fock (RHF) MO LCAO method.