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Electronic structure, mechanical and optical properties of ternary semiconductors Si <sub/>1-x</sub> Ge <sub/>x</sub> C (X?=?0, 0.25, 0.50, 0.75, 1)
摘要： The electronic structure of silicon carbide with increasing germanium content have been examined using first principles calculations based on density functional theory. The structural stability is analysed between two different phases, namely, cubic zinc blende and hexagonal phases. The zinc blende structure is found to be the stable one for all the Si1-xGexC semiconducting carbides at normal pressure. Effect of substitution of Ge for Si in SiC on electronic and mechanical properties is studied. It is observed that cubic SiC is a semiconductor with the band gap value 1.243 eV. The band gap value of SiC is increased due to the substitution of Ge and the band gap values of Si 0.75 Ge 0.25 C, Si 0.50 Ge 0.50 C, Si 0.25 Ge 0.75 C and GeC are 1.322 eV, 1.413 eV, 1.574 eV and 1.657 eV respectively. As the pressure is increased, it is found that the energy gap gets decreased for Si1-x GexC (X = 0, 0.25, 0.50, 0.75, 1). The elastic constants satisfy the Born – Huang elastic stability criteria. The bulk modulus, shear modulus, Young’s modulus and Poisson’s ratio are also calculated and compared with the other available results.
关键词： mechanical properties,electronic structure,optical properties,First principles study
更新于2025-09-23 15:23:52
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Investigation on electronic structure and luminescence mechanism of CaF2:Eu3+ from first principles calculations
摘要： In this work, we present the results of theoretical calculations based on the density functional theory (DFT) of structural, electronic and optical properties of CaF2 crystal doped with Eu3+ ion. This study covers both ground and excited states of considered material by ?xing spin magnetic moment 6μB and 4μB, respectively. The Eu3+ doping induces slight displacement of its nearest neighbors. The presence of Eu3+ ion is con?rmed by the calculated charge density and magnetic moment. Some electronic states belonging to 4f orbital are found in the forbidden energy region of CaF2 and the spin ?ipping of one 4f electron of Eu3+ caused by the excitation is demonstrated by means of the computed electronic properties. The absorption spectra of CaF2:Eu3+ is calculated and compared with that of pure CaF2. Finally, the possible mechanism of luminescence is proposed based on the obtained electronic and optical properties.
关键词： CaF2:Eu3+,First principles study,Electronic structure,Luminescence
更新于2025-09-23 15:22:29
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First-principles study on XV2S4 (X = Ni, Cr, and Mo) counter electrode for dye-sensitized solar cells
摘要： Structural, electronic, and optical properties of ternary vanadium sulfides, XV2S4 (X = Ni, Cr, and Mo), are investigated using first-principles calculations based on density functional theory (DFT) method. The structural parameters, band structures, density of states (DOS), absorption coefficient, and conductivity are reported to discuss the properties of XV2S4 (X = Ni, Cr, and Mo) as potential Pt-free counter electrode for dye-sensitized solar cell (DSSC). Generally, nickel vanadium sulfide (NiV2S4) is predicted to be a good candidate as a counter electrode compares with chromium vanadium sulfide (CrV2S4) and molybdenum vanadium sulfide (MoV2S4) due to its ability to provide high electron density around Fermi level and high conductivity.
关键词： Electronic properties,First-principles study,Counter electrode,Optical properties,Pt-free
更新于2025-09-23 15:21:01
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Effect of position and concentration of Li on ZnO physical properties : Density functional investigation
摘要： In this paper, we study the effect of Li position on the physical properties of Li doped ZnO with different concentrations (6.25%,12.5% and 18.75%), by using density functional theory and Boltzmann transport theory. In this work, two possible configurations of Li-doped ZnO are considered : substitution of Zn by Li atom (LiZn), and Li takes the interstitial position (Lii). It is found found that the position and the concentration of Li play an important role in determining the suitable applications for Li doped ZnO. It is also shown that the obtained results are in good agreement with experimental studies.
关键词： Li doped ZnO,Electronic Structure,First principles study,interstitial.,substitution
更新于2025-09-19 17:15:36
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A new two-dimensional semiconducting carbon allotrope: A first-principles study
摘要： A new two-dimensional carbon allotrope, which consists of 18 atoms in a hexagonal cell, is theoretically investigated by performing first-principle method. The allotrope displays a P6/mmm symmetry (termed as hP-C18 carbon). The new 2D carbon phase has an sp2-sp3 network, consisting of hexagons and octagons formed by near-by atoms. The calculations demonstrate that hP-C18 carbon is a metastable 2D carbon phase compared to graphene, but it is more energetically stable than penta-graphene. The dynamical, thermal and mechanical stabilities are demonstrated by phonon dispersion, ab inito MD simulations and elastic constants, respectively. The analysis of electronic band structure shows that hP-C18 is an indirect semiconductor with a band gap of 2.93 eV (HSE06). Besides, its buckled 3D structure, hP-C18-3D carbon, is also predicted. The stability of the new 3D phase is discussed by phonon dispersion and elastic constants. It is found that hP-C18-3D carbon is a super-hard indirect semiconductor with an indirect band gap of 2.24 eV (HSE06). Thus, hP-C18 carbon and its buckled 3D structure may possess not only potential electronic applications but also mechanical applications.
关键词： metastable,hP-C18 carbon,two-dimensional carbon allotrope,semiconducting,mechanical applications,first-principles study,electronic applications
更新于2025-09-10 09:29:36