amirullah mamedov - Profile on Academia.edu (original) (raw)
Papers by amirullah mamedov
We have performed a first principles study of structural, elastic, and electronic properties of r... more We have performed a first principles study of structural, elastic, and electronic properties of rhombohedral Sb2 Te3 and Bi2 Te3 compounds using the density functional theory within the local density approximation. The lattice parameters of considered compounds have been calculated. The second-order elastic constants have been calculated, and the other related quantities such as the Young's modulus, shear modulus, Poisson's ratio, anisotropy factor, sound velocities, and Debye temperature have also been estimated in the present work. The calculated electronic band structure shows that Sb2 Te3 and Bi2 Te3 compounds have a direct forbidden band gap. Our structural estimation and some other results are in agreement with the available experimental and theoretical data.
Journal of physics, Jun 1, 2018
First-principle calculations performed the structural, mechanical, electronic, and optical proper... more First-principle calculations performed the structural, mechanical, electronic, and optical properties of Sb 2 O 3 and Bi 2 O 3 compounds in monoclinic (claudetite and α-Bi 2 O 3 ) and orthorhombic (valentinite) structures. Local density approximation has been used for modeling exchange-correlation effects. The lattice parameters, bulk modulus, and the first derivate of bulk modulus (to fit to the Murnaghan's equation of state) of considered compounds have been calculated. The second-order elastic constants have been calculated, and the other related quantities have also been estimated in the present work. The electronic bands structures and the partial densities of states corresponding to the band structures are presented and analyzed. The real and imaginary parts of dielectric functions and energyloss function are calculated. Our structural estimation and some other results are in agreement with the available experimental and theoretical data.
Physica, 1985
In the present paper the near-normal incidence reflectance for LiNbO3 has been measured in the en... more In the present paper the near-normal incidence reflectance for LiNbO3 has been measured in the energy region 1.0 to 35.0 eV. Optical functions for the 0-35.0 eV range were determined by the Kramers-Kronig method (including the results for the low-energy region obtained previously). On the base of the experimental results, the energy transition diagram for LiNbO3 has been drawn, and the NbO6 octahedron is shown to be prominent in the formation of the band structure of the crystal studied. At low temperatures (T = 6 K) indirect optical transitions are observed for LiNbO3.
Multilayer Scattering Model: Structural Changes in the Cytoplasmic Nucleus Like Bodies
InterConf, Jun 22, 2021
Investigation on the Structure of PLZT Ceramics Due to Light Scattering
Key Engineering Materials, 2004
Abstract. Light scattering and its propagation through the PLZT ceramics is presented at the phas... more Abstract. Light scattering and its propagation through the PLZT ceramics is presented at the phase transition. TMM is applied to this structure, as a computational method for light scattering. This method is described in detail computational light scattering by polydispersive, randomly oriented rotationally symmetric particles. Our results associated with light wave propagation within the ferroelectric materials. The transmitted and the scattered intensities of incident plane wave are calculated for various combinations and geometry via to different parameters. Also, ferroic correlation between the PLZT structure and the light scattering is briefly discussed.
Építőanyag, 2022
In this paper, we investigated the bandgaps of two-dimensional phononic crystals with quasi-Sierp... more In this paper, we investigated the bandgaps of two-dimensional phononic crystals with quasi-Sierpinski carpet unit cells in a metacomposite based solid-solid phononic crystal. Finite element method was used to analyze the properties of two-dimensional phononic bandgaps (2D PBGs) in a quasi-fractal structure. Two new types of quasi-Sierpinski fractal unit cells whose constituents are homogeneous and isotropic were proposed to obtain larger full bandgaps. The results show that the PBGs of the proposed quasi-Sierpinski fractals are suitable to tune the PBG's without changing the size of the phonic crystal. The new quasi-Sierpinski fractals also retain the selfsimilarity as in the third-order Sierpinski fractal unit cell. The investigated quasi-fractals can be easily modified to increase the filling fraction of the constituents, which can be effectively used to enlarge existing PBG by preserving degree of self-similarity structure.
Applied Physics A, Dec 19, 2016
The vast majority of acoustic wave propagation in phononic band studies has been usually carried ... more The vast majority of acoustic wave propagation in phononic band studies has been usually carried out by scattering inclusions embedded in a viscoelastic medium, such as air or water. In this study, we present calculated band structure results for the two-dimensional square array geometry of a solid cylindrical scatterer surrounded by a liquid crystal (LC) matrix. Liquid crystals provide a unique combination of liquidlike and crystal-like properties as well as anisotropic properties. The purpose of using LC material is to take advantage of longitudinal acoustic waves propagating parallel (||) and perpendicular (\) to the nematic liquid crystal (NLC) director n. The compound used in this study was a room temperature NLC, called 5CB (4-pentyl-4 0 -cyanobiphenyl). The acoustic band structure of a two-dimensional phononic crystal containing a 5CB NLC and lithium tantalate was investigated by the plane wave expansion method. The theoretical results show that the solid/LC system can be tuned in a favorable configuration for adjusting or shifting acoustic band gaps.
Applied Physics A, Mar 1, 2017
major fields in acoustics. Sonic crystals (SCs) are defined as structured materials formed by a p... more major fields in acoustics. Sonic crystals (SCs) are defined as structured materials formed by a periodic distributions of acoustic scatterers embedded in a host material, with strong periodic modulations in their density and elastic coefficients between the constituent materials. The periodicity of the scatterers in a surrounding material gives rise to the appearance of sonic band gaps, a range of frequencies for which sound propagation is forbidden inside the crystal. These stop bands were observed at frequencies depending on the lattice constant of the array in the band structures of crystals with various lattice geometries [3-5]. The SCs have induced several application proposals and enabled development of many new technologies. Recent studies in this field have attracted a great interest due to the splendid application prospects, such as acoustic filters [6, 7], shield devices [8-10], defect states for acoustic filters and wave guides [11], and so on. Recently, an increased attenuation at low frequencies has been achieved by the locally resonant sonic materials formed by soft and rigid elements [12]. Several theoretical methods have been used to study the elastic/acoustic band structures, such as, the plane-wave expansion (PWE) method [13, 14], the finite difference time domain (FDTD) method [15], the extended plane wave expansion (EPWE) method [16, 17], the multiple scattering theory (MST) [18], perturbative approach [19], and variational method [20]. Among them, the PWE is the most widely used method for calculating the band structures. In the literature, acoustic band gaps of various two-dimensional sonic crystal structures were investigated and these structures mostly consist of circular cross-section scatterers in square, triangular, rectangular lattices, the constituent being either both solids or fluids, or mixed solid-fluid [21]. Practically, band gaps properties of sonic crystal structures or the acoustic dispersion of the branches can be controlled by the lattice filling factor, the constituent Abstract The propagation of acoustic waves in twodimensional sonic crystals (SC) is studied theoretically. Effects of elliptical rod orientations on the acoustic band gaps in periodic arrays of rigid solid rods embedded in a polar liquid are investigated. We have found that the pass bands and forbidden bands of the sonic crystals can be changed by utilizing the rotational anisotropy of the structure factor at different rotation angles of the scatterers. The plane wave expansion (PWE) method is used to calculate the band structure. The variation of the absolute band gap was also investigated as a function of any filling fraction at a fixed orientation of the elliptical columns. The gap-tuning effect can be controlled by the rotational asymmetry and eccentricity of the scatterers.
Physica status solidi, Jul 16, 1980
of Sciences of the USSR, Leningrad (b) Electrical Properties of Electron (2 MeV) Irradiated p-CdS... more of Sciences of the USSR, Leningrad (b) Electrical Properties of Electron (2 MeV) Irradiated p-CdSiAs2 and p-ZnSiAs2 Crystals BY V.N. BRUDNYI (a), M.A. KRIVOV (a), A. MAMEDOV (b), A.I. POTAPOV (a), V.D. PROCHUKHAN ( b), and YU.V. RUD (b) 'Up to date the ternary semiconducting CdSiAs2 and ZnSiAs2 compounds a r e
Kramers-Kronig analysis of the reflection spectra of Ba 2 NaNb 5 O 15
Optics and Spectroscopy, Jul 1, 1982
Electronic structure and VUV-spectroscopy of rare earth molybdates
Izvestiya Vysshikh Uchebnykh Zavedenij, Fizika, 1986
Physica Status Solidi (a), 1980
Electrical Properties of Electron (2 MeV) Irradiated p-CdSiAs2 and p-ZnSiAs2 Crystals BY V.N. BRU... more Electrical Properties of Electron (2 MeV) Irradiated p-CdSiAs2 and p-ZnSiAs2 Crystals BY V.N. BRUDNYI (a), M.A. KRIVOV (a), A. MAMEDOV (b), A.I. POTAPOV (a), V.D. PROCHUKHAN (b), and YU.V. RUD (b) 'Up to date the ternary semiconducting CdSiAs2 and ZnSiAs2 compounds a r e
Physica B+C, 1984
In the present paper the near-normal incidence reflectance for BaxSr~-xNb206 (0.25 ~< x ~< 0.75) ... more In the present paper the near-normal incidence reflectance for BaxSr~-xNb206 (0.25 ~< x ~< 0.75) and Ba2NaNbsOt5 has been measured in the energy region 1.0 to 35.0 eV. The optical constants for the region 0 to 35.0 eV have been derived from a Kramers-Kronig analysis. In the energy region 3.0 to 12.0 eV all the data obtained can be explained as the result of interband transitions from the valence band formed by O 2p orbitals to Nb 4d conduction band splitted in this case into two sub-bands (de, dy) with a distance of about 5 eV between them. In the high energy region (~>15 eV), however, the extrema in the e2 spectra are attributed to the transitions from core levels (O2s, Sr4p, Ba5p3/2, Ba5pv2) to the conduction band. In this region the spin-orb~ital splitting of the Sr 4p core level, A = 0.6 eV, is also observed. On the base of the data obtained, the energy transition diagram of the crystals investigated has been drawn up. The BO6 oetahedron is shown to be prominent in the formation of the band structure of these crystals.
Journal of Engineering Physics, 1977
Using water and toluene as examples, it was established that the ratio between the coefficients o... more Using water and toluene as examples, it was established that the ratio between the coefficients of thermal conductivity and dynamic viscosity at high state parameters was proportional to the density to the power ~.
International Symposium Innovative Technologies Engineering and Science, Sep 29, 2017
Metamaterials are artificial materials that possess unusual physical properties that are not usua... more Metamaterials are artificial materials that possess unusual physical properties that are not usually found in natural materials. Phononic crystals (PnC) can be constructed by periodic distribution of inclusions embedded in a matrix with high contrast in mechanical properties. They can forbid the propagations of acoustic waves in certain frequencies by creating band gaps. Such band gaps may be independent of the direction of propagation of the incident wave. In present work the acoustic band structure of a two-dimensional phononic crystal consisting of square-shaped rods embedded in air matrix are studied to find the existence of stop bands for the waves of certain energy. The wave band structures of acoustic waves in 2D air/solid phononic structure are investigated theoretically by Finite Element (FE) simulations. A time harmonic analysis of the acoustic wave propagation is performed using the acoustics package of the FE software Comsol Multiphysics v5.3. Phononic band diagrams ω=ω(k) for a 2D PnC were plotted versus the wavevector k along the M-Г-X-M path in the first Brillouin zone. The calculated phonon dispersion results indicate the existence of full acoustic modes in the proposed structure along the high symmetry points.
World Journal of Condensed Matter Physics, 2015
In this work, we have investigated the electronic and optical properties of the technologically i... more In this work, we have investigated the electronic and optical properties of the technologically important rare earth oxide compounds-X2O3 (X: Gd, Tb) using the density functional theory within the GGA. The band structure of X2O3 have been calculated along high symmetry directions in the first brillouin zone. The real and imaginary parts of dilectric functions and the other optical responses such as energy-loss function, the effective number of valence electrons and the effective optical dielectric constants of the rare earth sesquioxides (Gd2O3 and Tb2O3) were calculated.
Ferroelectrics, May 19, 2019
We present band structure results for elastic waves in periodic composite materials consisting of... more We present band structure results for elastic waves in periodic composite materials consisting of a spiral scatterer shape embedded in a uniform silicon matrix. The material of the scatterer is tungsten as a high density material. The phononic band structure of two-dimensional solid phononic crystal is studied numerically by finite element method to obtain dispersion relations. We find full band gaps at relatively low frequencies for a low filling ratio. Due to spatial inhomogeneity, the unique structural characteristics of the spiral structure lead to localized modes. Hence, the proposed model geometry introduces a phononic crystal to cover a wide range of stopbands starting from low frequencies. The results could give a possibility to design effective filters for the low frequency range.
International Journal of Scientific and Technological Research, 2015
In this work, we have investigated the electronic and optical properties of the technologically i... more In this work, we have investigated the electronic and optical properties of the technologically important rare earth oxide compound-Dy2O3 using the density functional theory within the GGA. The band structure of Dy2O3 has been calculated along high symmetry directions in the first Brillouin zone. The real and imaginary parts of dilectric functions and the other optical responses such as energy-loss function, the effective number of valence electrons and the effective optical dielectric constants of the rare earth sesquioxide-Dy2O3 were calculated.
arXiv (Cornell University), May 7, 2013
In this report we present an investigation of the optical properties and band structure calculati... more In this report we present an investigation of the optical properties and band structure calculations for the photonic structures based on the functional materials-ferroelectrics. A theoretical approach to the optical properties of the 2D and 3D photonic crystals which yields further insight in the phenomenon of the reflection from different families of lattice planes in relation to the presence of photonic gaps or photonic bands. We calculate the photonic bands and optical properties of LiNbO 3 based photonic crystals. Calculations of reflection and transmission spectra show the features correspond to the onset of diffraction, as well as to additional reflectance structures at large values of the angle of incidence.
Ferroelectrics, Mar 11, 2020
In this study, the band structure and transmission in multiferroic based Sierpinski carpet phonon... more In this study, the band structure and transmission in multiferroic based Sierpinski carpet phononic crystal are investigated based on finite element simulation. In order to obtain the band structure of the phononic crystal (PnC), the Floquet periodicity conditions were applied to the sides of the unit cell. The square lattice PnC consists of various piezoelectric inclusion in a rubber matrix with square and circular cross section.
We have performed a first principles study of structural, elastic, and electronic properties of r... more We have performed a first principles study of structural, elastic, and electronic properties of rhombohedral Sb2 Te3 and Bi2 Te3 compounds using the density functional theory within the local density approximation. The lattice parameters of considered compounds have been calculated. The second-order elastic constants have been calculated, and the other related quantities such as the Young's modulus, shear modulus, Poisson's ratio, anisotropy factor, sound velocities, and Debye temperature have also been estimated in the present work. The calculated electronic band structure shows that Sb2 Te3 and Bi2 Te3 compounds have a direct forbidden band gap. Our structural estimation and some other results are in agreement with the available experimental and theoretical data.
Journal of physics, Jun 1, 2018
First-principle calculations performed the structural, mechanical, electronic, and optical proper... more First-principle calculations performed the structural, mechanical, electronic, and optical properties of Sb 2 O 3 and Bi 2 O 3 compounds in monoclinic (claudetite and α-Bi 2 O 3 ) and orthorhombic (valentinite) structures. Local density approximation has been used for modeling exchange-correlation effects. The lattice parameters, bulk modulus, and the first derivate of bulk modulus (to fit to the Murnaghan's equation of state) of considered compounds have been calculated. The second-order elastic constants have been calculated, and the other related quantities have also been estimated in the present work. The electronic bands structures and the partial densities of states corresponding to the band structures are presented and analyzed. The real and imaginary parts of dielectric functions and energyloss function are calculated. Our structural estimation and some other results are in agreement with the available experimental and theoretical data.
Physica, 1985
In the present paper the near-normal incidence reflectance for LiNbO3 has been measured in the en... more In the present paper the near-normal incidence reflectance for LiNbO3 has been measured in the energy region 1.0 to 35.0 eV. Optical functions for the 0-35.0 eV range were determined by the Kramers-Kronig method (including the results for the low-energy region obtained previously). On the base of the experimental results, the energy transition diagram for LiNbO3 has been drawn, and the NbO6 octahedron is shown to be prominent in the formation of the band structure of the crystal studied. At low temperatures (T = 6 K) indirect optical transitions are observed for LiNbO3.
Multilayer Scattering Model: Structural Changes in the Cytoplasmic Nucleus Like Bodies
InterConf, Jun 22, 2021
Investigation on the Structure of PLZT Ceramics Due to Light Scattering
Key Engineering Materials, 2004
Abstract. Light scattering and its propagation through the PLZT ceramics is presented at the phas... more Abstract. Light scattering and its propagation through the PLZT ceramics is presented at the phase transition. TMM is applied to this structure, as a computational method for light scattering. This method is described in detail computational light scattering by polydispersive, randomly oriented rotationally symmetric particles. Our results associated with light wave propagation within the ferroelectric materials. The transmitted and the scattered intensities of incident plane wave are calculated for various combinations and geometry via to different parameters. Also, ferroic correlation between the PLZT structure and the light scattering is briefly discussed.
Építőanyag, 2022
In this paper, we investigated the bandgaps of two-dimensional phononic crystals with quasi-Sierp... more In this paper, we investigated the bandgaps of two-dimensional phononic crystals with quasi-Sierpinski carpet unit cells in a metacomposite based solid-solid phononic crystal. Finite element method was used to analyze the properties of two-dimensional phononic bandgaps (2D PBGs) in a quasi-fractal structure. Two new types of quasi-Sierpinski fractal unit cells whose constituents are homogeneous and isotropic were proposed to obtain larger full bandgaps. The results show that the PBGs of the proposed quasi-Sierpinski fractals are suitable to tune the PBG's without changing the size of the phonic crystal. The new quasi-Sierpinski fractals also retain the selfsimilarity as in the third-order Sierpinski fractal unit cell. The investigated quasi-fractals can be easily modified to increase the filling fraction of the constituents, which can be effectively used to enlarge existing PBG by preserving degree of self-similarity structure.
Applied Physics A, Dec 19, 2016
The vast majority of acoustic wave propagation in phononic band studies has been usually carried ... more The vast majority of acoustic wave propagation in phononic band studies has been usually carried out by scattering inclusions embedded in a viscoelastic medium, such as air or water. In this study, we present calculated band structure results for the two-dimensional square array geometry of a solid cylindrical scatterer surrounded by a liquid crystal (LC) matrix. Liquid crystals provide a unique combination of liquidlike and crystal-like properties as well as anisotropic properties. The purpose of using LC material is to take advantage of longitudinal acoustic waves propagating parallel (||) and perpendicular (\) to the nematic liquid crystal (NLC) director n. The compound used in this study was a room temperature NLC, called 5CB (4-pentyl-4 0 -cyanobiphenyl). The acoustic band structure of a two-dimensional phononic crystal containing a 5CB NLC and lithium tantalate was investigated by the plane wave expansion method. The theoretical results show that the solid/LC system can be tuned in a favorable configuration for adjusting or shifting acoustic band gaps.
Applied Physics A, Mar 1, 2017
major fields in acoustics. Sonic crystals (SCs) are defined as structured materials formed by a p... more major fields in acoustics. Sonic crystals (SCs) are defined as structured materials formed by a periodic distributions of acoustic scatterers embedded in a host material, with strong periodic modulations in their density and elastic coefficients between the constituent materials. The periodicity of the scatterers in a surrounding material gives rise to the appearance of sonic band gaps, a range of frequencies for which sound propagation is forbidden inside the crystal. These stop bands were observed at frequencies depending on the lattice constant of the array in the band structures of crystals with various lattice geometries [3-5]. The SCs have induced several application proposals and enabled development of many new technologies. Recent studies in this field have attracted a great interest due to the splendid application prospects, such as acoustic filters [6, 7], shield devices [8-10], defect states for acoustic filters and wave guides [11], and so on. Recently, an increased attenuation at low frequencies has been achieved by the locally resonant sonic materials formed by soft and rigid elements [12]. Several theoretical methods have been used to study the elastic/acoustic band structures, such as, the plane-wave expansion (PWE) method [13, 14], the finite difference time domain (FDTD) method [15], the extended plane wave expansion (EPWE) method [16, 17], the multiple scattering theory (MST) [18], perturbative approach [19], and variational method [20]. Among them, the PWE is the most widely used method for calculating the band structures. In the literature, acoustic band gaps of various two-dimensional sonic crystal structures were investigated and these structures mostly consist of circular cross-section scatterers in square, triangular, rectangular lattices, the constituent being either both solids or fluids, or mixed solid-fluid [21]. Practically, band gaps properties of sonic crystal structures or the acoustic dispersion of the branches can be controlled by the lattice filling factor, the constituent Abstract The propagation of acoustic waves in twodimensional sonic crystals (SC) is studied theoretically. Effects of elliptical rod orientations on the acoustic band gaps in periodic arrays of rigid solid rods embedded in a polar liquid are investigated. We have found that the pass bands and forbidden bands of the sonic crystals can be changed by utilizing the rotational anisotropy of the structure factor at different rotation angles of the scatterers. The plane wave expansion (PWE) method is used to calculate the band structure. The variation of the absolute band gap was also investigated as a function of any filling fraction at a fixed orientation of the elliptical columns. The gap-tuning effect can be controlled by the rotational asymmetry and eccentricity of the scatterers.
Physica status solidi, Jul 16, 1980
of Sciences of the USSR, Leningrad (b) Electrical Properties of Electron (2 MeV) Irradiated p-CdS... more of Sciences of the USSR, Leningrad (b) Electrical Properties of Electron (2 MeV) Irradiated p-CdSiAs2 and p-ZnSiAs2 Crystals BY V.N. BRUDNYI (a), M.A. KRIVOV (a), A. MAMEDOV (b), A.I. POTAPOV (a), V.D. PROCHUKHAN ( b), and YU.V. RUD (b) 'Up to date the ternary semiconducting CdSiAs2 and ZnSiAs2 compounds a r e
Kramers-Kronig analysis of the reflection spectra of Ba 2 NaNb 5 O 15
Optics and Spectroscopy, Jul 1, 1982
Electronic structure and VUV-spectroscopy of rare earth molybdates
Izvestiya Vysshikh Uchebnykh Zavedenij, Fizika, 1986
Physica Status Solidi (a), 1980
Electrical Properties of Electron (2 MeV) Irradiated p-CdSiAs2 and p-ZnSiAs2 Crystals BY V.N. BRU... more Electrical Properties of Electron (2 MeV) Irradiated p-CdSiAs2 and p-ZnSiAs2 Crystals BY V.N. BRUDNYI (a), M.A. KRIVOV (a), A. MAMEDOV (b), A.I. POTAPOV (a), V.D. PROCHUKHAN (b), and YU.V. RUD (b) 'Up to date the ternary semiconducting CdSiAs2 and ZnSiAs2 compounds a r e
Physica B+C, 1984
In the present paper the near-normal incidence reflectance for BaxSr~-xNb206 (0.25 ~< x ~< 0.75) ... more In the present paper the near-normal incidence reflectance for BaxSr~-xNb206 (0.25 ~< x ~< 0.75) and Ba2NaNbsOt5 has been measured in the energy region 1.0 to 35.0 eV. The optical constants for the region 0 to 35.0 eV have been derived from a Kramers-Kronig analysis. In the energy region 3.0 to 12.0 eV all the data obtained can be explained as the result of interband transitions from the valence band formed by O 2p orbitals to Nb 4d conduction band splitted in this case into two sub-bands (de, dy) with a distance of about 5 eV between them. In the high energy region (~>15 eV), however, the extrema in the e2 spectra are attributed to the transitions from core levels (O2s, Sr4p, Ba5p3/2, Ba5pv2) to the conduction band. In this region the spin-orb~ital splitting of the Sr 4p core level, A = 0.6 eV, is also observed. On the base of the data obtained, the energy transition diagram of the crystals investigated has been drawn up. The BO6 oetahedron is shown to be prominent in the formation of the band structure of these crystals.
Journal of Engineering Physics, 1977
Using water and toluene as examples, it was established that the ratio between the coefficients o... more Using water and toluene as examples, it was established that the ratio between the coefficients of thermal conductivity and dynamic viscosity at high state parameters was proportional to the density to the power ~.
International Symposium Innovative Technologies Engineering and Science, Sep 29, 2017
Metamaterials are artificial materials that possess unusual physical properties that are not usua... more Metamaterials are artificial materials that possess unusual physical properties that are not usually found in natural materials. Phononic crystals (PnC) can be constructed by periodic distribution of inclusions embedded in a matrix with high contrast in mechanical properties. They can forbid the propagations of acoustic waves in certain frequencies by creating band gaps. Such band gaps may be independent of the direction of propagation of the incident wave. In present work the acoustic band structure of a two-dimensional phononic crystal consisting of square-shaped rods embedded in air matrix are studied to find the existence of stop bands for the waves of certain energy. The wave band structures of acoustic waves in 2D air/solid phononic structure are investigated theoretically by Finite Element (FE) simulations. A time harmonic analysis of the acoustic wave propagation is performed using the acoustics package of the FE software Comsol Multiphysics v5.3. Phononic band diagrams ω=ω(k) for a 2D PnC were plotted versus the wavevector k along the M-Г-X-M path in the first Brillouin zone. The calculated phonon dispersion results indicate the existence of full acoustic modes in the proposed structure along the high symmetry points.
World Journal of Condensed Matter Physics, 2015
In this work, we have investigated the electronic and optical properties of the technologically i... more In this work, we have investigated the electronic and optical properties of the technologically important rare earth oxide compounds-X2O3 (X: Gd, Tb) using the density functional theory within the GGA. The band structure of X2O3 have been calculated along high symmetry directions in the first brillouin zone. The real and imaginary parts of dilectric functions and the other optical responses such as energy-loss function, the effective number of valence electrons and the effective optical dielectric constants of the rare earth sesquioxides (Gd2O3 and Tb2O3) were calculated.
Ferroelectrics, May 19, 2019
We present band structure results for elastic waves in periodic composite materials consisting of... more We present band structure results for elastic waves in periodic composite materials consisting of a spiral scatterer shape embedded in a uniform silicon matrix. The material of the scatterer is tungsten as a high density material. The phononic band structure of two-dimensional solid phononic crystal is studied numerically by finite element method to obtain dispersion relations. We find full band gaps at relatively low frequencies for a low filling ratio. Due to spatial inhomogeneity, the unique structural characteristics of the spiral structure lead to localized modes. Hence, the proposed model geometry introduces a phononic crystal to cover a wide range of stopbands starting from low frequencies. The results could give a possibility to design effective filters for the low frequency range.
International Journal of Scientific and Technological Research, 2015
In this work, we have investigated the electronic and optical properties of the technologically i... more In this work, we have investigated the electronic and optical properties of the technologically important rare earth oxide compound-Dy2O3 using the density functional theory within the GGA. The band structure of Dy2O3 has been calculated along high symmetry directions in the first Brillouin zone. The real and imaginary parts of dilectric functions and the other optical responses such as energy-loss function, the effective number of valence electrons and the effective optical dielectric constants of the rare earth sesquioxide-Dy2O3 were calculated.
arXiv (Cornell University), May 7, 2013
In this report we present an investigation of the optical properties and band structure calculati... more In this report we present an investigation of the optical properties and band structure calculations for the photonic structures based on the functional materials-ferroelectrics. A theoretical approach to the optical properties of the 2D and 3D photonic crystals which yields further insight in the phenomenon of the reflection from different families of lattice planes in relation to the presence of photonic gaps or photonic bands. We calculate the photonic bands and optical properties of LiNbO 3 based photonic crystals. Calculations of reflection and transmission spectra show the features correspond to the onset of diffraction, as well as to additional reflectance structures at large values of the angle of incidence.
Ferroelectrics, Mar 11, 2020
In this study, the band structure and transmission in multiferroic based Sierpinski carpet phonon... more In this study, the band structure and transmission in multiferroic based Sierpinski carpet phononic crystal are investigated based on finite element simulation. In order to obtain the band structure of the phononic crystal (PnC), the Floquet periodicity conditions were applied to the sides of the unit cell. The square lattice PnC consists of various piezoelectric inclusion in a rubber matrix with square and circular cross section.