maryam azizi; hamdollah salehi
Abstract
In the LDA approximation with the pseudo-potential method, and from the density of states diagram, the value of the band gap are 1.2 eV, 1.4 eV, and 2.37 eV, in the LDA and LDA+U and HSE approximations, respectively, were obtained with norm conserving pseudo-potential. Also, the calculated bulk moduls ...
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In the LDA approximation with the pseudo-potential method, and from the density of states diagram, the value of the band gap are 1.2 eV, 1.4 eV, and 2.37 eV, in the LDA and LDA+U and HSE approximations, respectively, were obtained with norm conserving pseudo-potential. Also, the calculated bulk moduls value were 81 GPa in LDA, 79.4 GPa in LDA+U, and 76.5 GPa in HSE approximation. Finally, the optical properties were computed, such as refractive index, extinction coefficient, absorption coefficient, reflection coefficient and optical conductivity. From the examination of the optical properties, the optical gap value obtained from the absorption coefficient is in good agreement with the band gap value, which is Optical coefficients are different in different directions due to the anisotropy of the structure. The value of the optical gap that read from the absorption coefficient diagram in the approximation of LDA, LDA+U and HSE was 1.27 eV, 1.4 eV and 2.37 eV, respectively. Based on the optical investigations, this compound is useful in solar cells and optoelectronic materials.The value of the optical gap that read from the absorption coefficient diagram in the approximation of LDA, LDA+U and HSE was 1.27 eV, 1.4 eV and 2.37 eV, respectively.
Fateme Karami; Sara Mohammadi Bilankohi; Hossein Ghaforyan
Abstract
Using the density functional theory, the electronic, magnetic and optical properties of Ti2ScGe have been investigated. The first thing that should be examined is the stable structure for the full-Heusler compound, after the investigations, a structure named type a was considered in the ferromagnetic ...
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Using the density functional theory, the electronic, magnetic and optical properties of Ti2ScGe have been investigated. The first thing that should be examined is the stable structure for the full-Heusler compound, after the investigations, a structure named type a was considered in the ferromagnetic state. This compound is studied for the first time in this paper and in the investigated conditions, it was recognized as a ferromagnetic half-metallic with a half-metallic gap of 0.4 electron volts. This compound has several acceptable factors for its applicability in making spintronics devices. Such as, half-metallic properties, high Curie temperature around 1086 K, its stability in the ferromagnetic state, and following the Slater-Pauling rule. Also, the examination of the optical properties showed that the Ti2ScGe full-Heusler compound can be further studied as a wave absorber
Majid Ebrahimzadeh; Massomeh Salaki
Abstract
Plasmonic science has been noticed by researchers, with the increasing development of knowledge and technology in nanometer dimensions. Gold and silver ellipsoidal metal nanoparticles can exhibit unique optical properties due to their ellipsoidal structure with special symmetry and are therefore very ...
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Plasmonic science has been noticed by researchers, with the increasing development of knowledge and technology in nanometer dimensions. Gold and silver ellipsoidal metal nanoparticles can exhibit unique optical properties due to their ellipsoidal structure with special symmetry and are therefore very suitable options for use in the new generation of optical sensors. Therefore, in this work, the optical properties of gold and silver metal ellipsoidal nanoparticles were simulated in different dielectric environments as well as in different sizes with using the MATLAB program. The results show that with increasing the diameter of the ellipsoidal nanoparticles (flattened state) of gold, the peak of the absorption, scattering and extinction spectra increases, which can be a good option for plasmonic applications and optical devices. Also, compared to ellipsoidal nanoparticles (elongated state), the absorption and extinction efficiencies intensity are higher and the scattering peak appears at higher wavelengths, while for the elongated state, ellipsoidal nanoparticles do not show such a case. Due to the small number of conducting electrons in nanoparticles and the homogeneous displacement of free charges within the nanoparticle, it is only the bipolar distribution of free charges that causes single peaks in the extinction and absorption spectrum of ellipsoidal gold and silver nanoparticles.
Fatemeh Karami
Abstract
on density functional theory the electronic, magnetic and optical properties of the Cr2ScSb full-Heusler compound have been investigated. This compound has half-metallic gap of 0.07 eV at equilibrium lattice constant, but there is no band gap in the band structure.Cr2ScSb is stable in ferromagnet state. ...
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on density functional theory the electronic, magnetic and optical properties of the Cr2ScSb full-Heusler compound have been investigated. This compound has half-metallic gap of 0.07 eV at equilibrium lattice constant, but there is no band gap in the band structure.Cr2ScSb is stable in ferromagnet state. The total magnetic moment of Cr2ScSb is 4 μ_B and following the Slater-Pauling rule. Results of the investigation of optical properties showed that this compound is a good choice for use as an electromagnetic waves absorbent.
Syed Ali Hashemizadeh (Ph.D.); Maryam Masoudi; Masomeh Arabikhah; Zahra Abasi Azad
Volume 2, Issue 2 , June 2019, , Pages 25-32
Abstract
In this study, optical properties of BaTiO3/SrTiO3/CaTiO3 compounds such as reflective index, extinction coefficient, absorption coefficient, reflectivity, energy loss spectrum and optical conductivity have been calculated and investigated in their stable phases, rhombohedral/ cubic/ orthohorombic phase ...
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In this study, optical properties of BaTiO3/SrTiO3/CaTiO3 compounds such as reflective index, extinction coefficient, absorption coefficient, reflectivity, energy loss spectrum and optical conductivity have been calculated and investigated in their stable phases, rhombohedral/ cubic/ orthohorombic phase with p4mm/m3m/pbnm space group respectively. The calculations have been conducted with pseudo-potential by GGA approximation in the frame work of Density Functional Theory. The obtained results for constant lattice after optimization, static dielectric constant, reflective index and plasma frequency have good accord with the experimental results and other theoretic studies. With respect to these quantities, perovskite oxides are good dielectrics. With respect to dielectic constants, and suitable optical absorbtion in the range of 4-12 eV, these perovskite oxides are good dielectrics. These compounds are transparent in energies above 13eV,and the maximum amount of conductivity occurs within 5eV. Also D coefficient calculated by Gladstone-Dale equation.