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We study the Be-C doped MgB_2 system by the first principles method based on density functional theory. The compensation effect between electron type doping and hole type doping is shown in the total density of states on the Fermi level, the real part of optical conductivity, and the number of effective carriers. The compensation mechanisms are discussed. The critical temperatures for different systems are calculated. 相似文献
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用第一性原理计算了Sn掺杂 β-Ga2O3、F掺杂β-Ga2O3和Sn/F共掺杂 β-Ga2O3的形成能、电子结构和光学性能。用LDA方法计算的本征β-Ga2O3和Sn掺杂 β-Ga2O3的晶格常数和电子结构与实验值吻合。形成能计算表明Sn掺杂 β-Ga2O3、F掺杂β-Ga2O3和Sn/F共掺杂 β-Ga2O3在富氧条件下比在富镓条件下容易形成。Sn掺杂 β-Ga2O3、F掺杂β-Ga2O3和Sn/F共掺杂 β-Ga2O3显示n型半导体特性。Sn/F共掺杂 β-Ga2O3具有最小的电子有效质量和最大的相对电子数,具有潜在的良好导电性。Sn/F共掺杂 β-Ga2O3在可见光区域显示强的光吸收。 相似文献
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Polycrystalline Mg1-xHgxB2 samples with x=0, 1%, 2.5%, 5%, 7.5%, and 10% have been synthesized by solid-state reaction. Different from the substitution effect of Al, C, Li, etc. on crystal structure of MgB2, Hg substitution for Mg results in an increase of the lattice constant in both a and c directions. The super- conductivity of MgB2 is also suppressed by Hg substitution. The observed suppression of super- conductivity by Hg substitution is discussed in terms of the interband impurity scattering effect in two-band superconductors. 相似文献
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By the total energy pseudo-potential approach of plane wave, we study the electronic and optical properties of the anatase TiO2 systems with Sc-doped, oxygen vacancies included, and Sc and oxygen vacancies co-existing, respectively. The obtained results show that the contribution by the doped Sc lies mainly in the valence band, and the light absorption in the visible region is obvious. A Mott phase transformation takes place in the presence of oxygen vacancies, and the light absorption in the visible region is also obvious. In particular, the absorption in the visible region of the co-doped system is enhanced coherently due to the influences both from doped Sc and oxygen vacancies. 相似文献
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Saadi Berri D. Maouche N. Bouarissa Y. Medkour 《Materials Science in Semiconductor Processing》2013,16(6):1439-1446
In this work, we study the structural, electronic and optical properties of AgSbS2, using full-potential linearized augmented plane wave and the pseudopotential plane wave scheme in the frame of generalized gradient approximation. Features such as the lattice constant, bulk modulus and its pressure derivative are reported. Our results suggest a phase transition from AF-IIb phase to rocksalt (B1) phase under high pressure. The calculated band structure and density of states show that the material under load has an indirect energy band gap X→(LГ) for AF-IIb phase (semiconductor) and a negative band gap W→(ГX) for B1 phase (semimetal). The optical properties are analyzed and the origin of some peaks in the spectra is discussed. Besides, the dielectric function, refractive index and extinction coefficient for radiation up to 14 eV have also been reported and discussed. 相似文献
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正Crystal structures and electronic structures of hafnium doping anatase TiO_2 were calculated by first principles with the plane-wave ultrasoft pseudopotential method based on the density functional theory within the generalized gradient approximation.The calculated results show that the lattice parameters a and c of Hf-doped anatase TiO_2 are larger than those of intrinsic TiO_2 under the same calculated condition.The calculated band structure and density of states show that the conduction band width of Hf-doped TiO_2 is broadened which results in the band gap of Hf-doped being smaller than the band gap of TiO_2. 相似文献
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The electronic and optical properties of the ternary Ga N1 xBix alloys in the zinc-blende structure are theoretically investigated by first principles calculations. Geometric optimization is performed before all the simulations to get accurate results. The band gaps of the alloys are found to be direct even with xD6.25%, and would become smaller when increasing the Bi compositions. The decrease ratio of band gaps is approximately 227 me V when 1% of N is replaced by Bi in the range of xD0–6.25%. Meanwhile, the absorption coefficient is shown to be significantly changed induced by the incorporation of Bi. These interesting properties indicate that Ga N1 xBix alloys could be a promising candidate in future optoelectronic applications. 相似文献
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Si-Hai Zhou 《中国电子科技》2008,6(2):157-161
MgB2 is a relatively new superconductor; it has attracted great interest from superconductor researchers all over the world. Thorough investigations have been carried out to study the material fabrication, as well as to study the material and superconducting properties from a fundamental physics point of view. The University of Wollongong has played a very active role in this research and a leading role in the research on high critical current density and high critical magnetic fields. Our recent research on the improvement of critical current density and the upper critical magnetic field by carbon-based compound doping is reviewed in this paper. 相似文献
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The structural, electronic, elastic and magnetic properties of gadolinium and its hydrides GdHx (x=1, 2, 3) are investigated by using Vienna ab-initio simulation package with the generalized gradient approximation parameterized by Perdew, Burke and Ernzerhof (GGA-PBE) plus a Hubbard parameter (GGA-PBE+U) in order to include the strong Coulomb correlation between localized Gd 4f electrons. At ambient pressure all the hydrides are stable in the ferromagnetic state. The calculated lattice parameters are in good agreement with the experimental results. The bulk modulus is found to decrease with the increase in the hydrogen content for the gadolinium hydrides. A pressure-induced structural phase transition is predicted to occur from cubic to hexagonal phase in GdH and GdH2 and from hexagonal to cubic phase in GdH3. The electronic structure reveals that mono and di-hydrides are metallic, whereas trihydride is half-metallic at normal pressure. On further increasing the pressure, a half-metallic to metallic transition is also observed in GdH3. The calculated magnetic moment values of GdHx (x=1, 2, 3) are in accord with the experimental values. 相似文献
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采用基于密度泛函理论(DFT)的第一性原理,研究了不同掺杂浓度下钼(Mo)掺杂SnO2的能带结构、电导率、吸收和反射率。建立了MoxSn1-xO2的三种掺杂模型(x=0.0625,0.125,0.1875),掺杂体系具有高电导率、高载流子密度和宽带隙的n型金属特征。随着掺杂浓度的增加,掺杂体系的带隙增加,电导率降低。Mo掺杂后,可见光区域的高透射性得以保留。特别地,在x=0.0625时实现了Mo掺杂SnO2的最佳电导率和光学性能。 相似文献
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The electronic and optical properties of SnSb4S7 compound are calculated by the full-potential linearized augmented plane-wave (FP-LAPW) method. The density of states (DOS) is carried out by the modified Becke-Johnson (mBJ) exchange potential approximation based on density functional theory (DFT). The compound SnSb4S7 has a monoclinic structure with the space group P21/m with lattice parameters of a=11.331 Å, b=3.865 Å and c=13.940 Å. The band gap is calculated to be 0.8 eV. The optical parameters, like dielectric constant, refractive index, reflectivity and energy loss function were also calculated and analyzed. The present work provides information about variation of the electronic and optical properties which reveals that SnSb4S7 is suitable for optoelectronic devices. 相似文献
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LiH电子结构与光学性质的密度泛函计算 总被引:1,自引:0,他引:1
采用基于密度泛函理论的平面波超软赝势方法计算了LiH晶体的电子结构和光学性质,给出了电子态密度、介电函数、吸收系数、复数折射率等计算结果,并对计算结果进行了分析.介电函数的虚部、吸收光谱、折射率等的峰值位置存在一一对应关系,这表明它们之间存在着内在的联系,与电子从价带到导带的跃迁吸收有关.Abstract: Electronic structure and optical properties of LiH crystal were investigated by using plane-wave ultra-soft pseudopotential method based on density functional theory. Electronic state density, dielectric function, absorption coefficient, and the complex reflectivity index of LiH crystal were calculated and analyzed. The peaks of the imaginary part of dielectric function, absorption spectra and complex reflectivity index of LiH crystal are corresponding with each other. Such results are related to the transition absorption of electrons from valence band to conduction band. 相似文献