In the last 30 days

• Open/close Spectral focusing characteristics of a grazing-incidence flat-field grating spectrometer

  Xie Xin-Hua et al 2004 Chinese Phys. 13 1826 Tag this article

  Article References Full text PDF (191 KB)

  The spectral focusing characteristics of a grazing-incidence flat-field spectrometer with a spherical variable-line-spacing grating in the 5–40nm spectral range are presented. The spectrometer can be used for any object at a distance in the 50mm–infinity range from the grating apex with a diffracted spectrum sharply focused on an almost flat focal plane at a constant distance from the grating apex.

• Open/close Exact solutions for the coupled Klein–Gordon–Schrödinger equations using the extended F-expansion method

  He Hong-Sheng et al 2005 Chinese Phys. 14 1926 Tag this article

  Article References Full text PDF (255 KB)

  The extended F-expansion method or mapping method is used to construct exact solutions for the coupled Klein-Gordon Schrödinger equations (K-G-S equations) by the aid of the symbolic computation system Mathematica. More solutions in the Jacobi elliptic function form are obtained, including the single Jacobi elliptic function solutions, combined Jacobi elliptic function solutions, rational solutions, triangular solutions, soliton solutions and combined soliton solutions.

• Open/close Calculation of the surface energy of fcc metals with modified embedded-atom method

  Zhang Jian-Min et al 2004 Chinese Phys. 13 1082 Tag this article

  Article References Full text PDF (263 KB)

  The surface energies for 38 surfaces of fcc metals Cu, Ag, Au, Ni, Pd, Pt, Al, Pb, Rh and Ir have been calculated by using the modified embedded-atom method. The results show that, for Cu, Ag, Ni, Al, Pb and Ir, the average values of the surface energies are very close to the polycrystalline experimental data. For all fcc metals, as predicted, the close-packed (111) surface has the lowest surface energy. The surface energies for the other surfaces increase linearly with increasing angle between the surfaces ( hkl) and (111). This can be used to estimate the relative values of the surface energy.

• Open/close Formation of graphene on Ru(0001) surface

  Pan Yi et al 2007 Chinese Phys. 16 3151 Tag this article

  Article References Full text PDF (872 KB)

  We report on the formation of a graphene monolayer on a Ru(0001) surface by annealing the Ru(0001) crystal. The samples are characterized by scanning tunnelling microscopy (STM) and Auger electron spectroscopy (AES). STM images show that the Moiré pattern is caused by the graphene layer mismatched with the underlying Ru(0001) surface and has an N × N superlattice. It is further found that the graphene monolayer on a Ru(0001) surface is very stable at high temperatures. Our results provide a simple and convenient method to produce a graphene monolayer on the Ru(0001) surface, which is used as a template for fabricating functional nanostructures needed in future nano devices and catalysis.

• Open/close Anisotropic properties of TaS₂

  Qiao Yan-Bin et al 2007 Chinese Phys. 16 3809 Tag this article

  Article References Full text PDF (908 KB)

  The anisotropic properties of 1T- and 2H-TaS ₂ are investigated by the density functional theory within the framework of full-potential linearized augmented plane wave method. The band structures of 1T- and 2H-TaS ₂ exhibit anisotropic properties and the calculated electronic specific-heat coefficient γ of 2H-TaS ₂ accords well with the existing experimental value. The anisotropic frequency-dependent dielectric functions including the effect of the Drude term are analysed, where the ε ^xx(ω) spectra corresponding to the electric field E perpendicular to the z axis show excellent agreement with the measured results except for the ε ₁ ^xx(ω) of 1T-TaS ₂ below the energy level of 2.6 eV which is due to the lack of the enough CDW information for reference in our calculation. Furthermore, based on the values of optical effective mass ratio P of 1T and 2H phases it is found that the anisotropy in 2H-TaS ₂ is stronger than that in 1T-TaS ₂.

• Open/close Ab initio calculations of electronic structure of anatase TiO₂

  Chen Qiang and Cao Hong-Hong 2004 Chinese Phys. 13 2121 Tag this article

  Article References Full text PDF (331 KB)

  This paper presents the results of the self-consistent calculations on the electronic structure of anatase phase of TiO ₂. The calculations were performed using the full potential-linearized augmented plane wave method (FP-LAPW) in the framework of the density functional theory (DFT) with the generalized gradient approximation (GGA). The fully optimized structure, obtained by minimizing the total energy and atomic forces, is in good agreement with experiment. We also calculated the band structure and the density of states. In particular, the calculated band structure prefers an indirect transition between valence and conduction bands of anatase TiO ₂, which may be helpful for clarifying the ambiguity in other theoretical works.

• Open/close Metastable phase separation and rapid solidification of undercooled Co-Cu alloy under different conditions

  Cao Chong-De 2006 Chinese Phys. 15 872 Tag this article

  Article References Full text PDF (517 KB)

  The metastable liquid phase separation and rapid solidification behaviours of Co _61.8Cu _38.2 alloy were investigated by using differential thermal analysis (DTA) in combination with glass fluxing, electromagnetic levitation (EML) and drop tube techniques. It is found that the liquid phase separation process and the solidification microstructures intensively depend on the experimental processing parameters, such as undercooling level, cooling rate, gravity level, liquid surface tension and the wetting state of crucible. Large undercooling and surface tension difference of the two liquids tend to facilitate further separation and cause severe macrosegregation. On the other hand, rapid cooling and low gravity effectively suppress the coalescence of the minority phase. Severe macrosegregation patterns are formed in the bulk samples processed by both DTA and EML. In contrast, disperse structures with fine spherical Cu-rich spheres homogeneously distributed in the matrix of Co-rich phase have been obtained in drop tube.

• Open/close Raman spectra of ZnSe nanoparticles synthesized by thermal evaporation method

  An Hui-Zhi et al 2004 Chinese Phys. 13 1753 Tag this article

  Article References Full text PDF (259 KB)

  ZnSe nanoparticles were synthesized by using a thermal evaporation method for a vapour phase reaction of zinc and selenium sources. The sample was characterized by XRD, TEM, HRTEM and Raman spectroscopy. Raman spectra of longitudinal-optical (LO) like mode was analysed by a macroscopic continuum dielectric model. Large broadening of LO-mode is homogeneous and comes from the relaxation of the phonons at the interface and contribution of defects. Surface modes give the main contribution to the asymmetry of the lineshape.

• Open/close Investigation of the characteristics of GIDL current in 90nm CMOS technology

  Chen Hai-Feng et al 2006 Chinese Phys. 15 645 Tag this article

  Article References Full text PDF (259 KB)

  A specially designed experiment is performed for investigating gate-induced drain leakage (GIDL) current in 90nm CMOS technology using lightly-doped drain (LDD) NMOSFET. This paper shows that the drain bias V _D has a strong effect on GIDL current as compared with the gate bias V _G at the same drain–gate voltage V _DG. It is found that the difference between I _D in the off-state I _D− V _G characteristics and the corresponding one in the off-state I _D− V _D characteristics, which is defined as I _DIFF, versus V _DG shows a peak. The difference between the influences of V _D and V _G on GIDL current is shown quantitatively by I _DIFF, especially in 90nm scale. The difference is due to different hole tunnellings. Furthermore, the maximum I _DIFF( I _DIFF,MAX) varies linearly with V _DG in logarithmic coordinates and also V _DG at I _DIFF,MAX with V _F which is the characteristic voltage of I _DIFF. The relations are studied and some related expressions are given.

• Open/close Study on the thermo-optic properties of DR1/PMMA composite

  Li Xiang et al 2006 Chinese Phys. 15 2439 Tag this article

  Article References Full text PDF (157 KB)

  This paper reports that the thermo-optic coefficient (d n/d T) as well as thermal expansion coefficients (β) of DR1/PMMA polymer film are measured for both TE (transversal electric) and TM (transversal magnetic) polarizations by using an attenuated total reflection configuration at the wavelengths of 832nm. The thermo-optic coefficients of DR1/PMMA are negative and as high as the order of 10 ⁻⁴/°C. The influences of dopant concentration, poling process and photobleaching process on the thermo-optic properties of DR1/PMMA are also investigated.