Structural and optical properties of polycrystalline CdSexTe1−x (0 ≤ x ≤ 0.4) thin films

CdSe_xTe_1−x (0 ≤ x ≤ 0.4) ternary thin films have been deposited on quartz substrates at room temperature by a single source thermal evaporation. X-ray diffraction patterns and transmission electron microscope micrographs of these films showed that the films were of polycrystalline texture over the whole range studied and exhibit predominant cubic (zinc blende) structure with strong preferential orientation of the crystallites along (1 1 1) direction. Linear variation of the lattice constant with mole fraction x is observed obeying Vegard's law. The dependence of the optical constants, the refractive index n and extinction coefficient k, of the films on the mole fraction x was studied in the spectral range of 400-2500 nm. The normal dispersion of the refractive index of the films could be described using the Wemple-DiDomenco single-oscillator model. CdSe_xTe_1−x thin films of different composition have two direct and indirect transitions corresponding to energy gaps and . The variation in either or with x indicates that this system belongs to the amalgamation type. The variation follows a subquadratic dependence and the bowing parameters were found to be 0.36 and 0.48 eV for the direct, and indirect energy gaps, respectively. Direct linear variation of the ratio N/m^* with x is observed.     

Cu diffusion along Al grain boundaries

Cu grain boundary diffusion (GBD) in Al was investigated by EPMA in temperature range from 300 to 400 °C.The triple product sδD_gb (s—segregation coefficient, δ—grain boundary width, D_gb—GBD coefficient) was calculated due to Fisher-Gibbs solution using two methods—measuring of GB concentration in dependence on penetration depth and the contour angle (at the top of diffusion wedge). In the first case ; in the second .     

Synthesis of LaRhAsO and superconductivity within the LaFe1−xRhxAsO system

The compound LaRhAsO is reported for the first time. We show that an entire LaFe_1−xRh_xAsO solid solution is possible. Powder X-ray diffraction, resistivity and magnetic measurements were carried out on polycrystalline samples. Superconductivity onset is observed for x = 0.05, 0.10, and 0.15 with a maximum resistivity of ∼16 K. The fluorine doped samples of the new compound LaRhAsO remain metallic down to 5 K.     

Thermal conductivity of single and multi-stacked DI-BSCCO tapes

We have measured the temperature dependence of the thermal conductivity, κ(T), for DI-BSCCO^® tapes fabricated by Sumitomo Electric Industries, Ltd., which are (Bi,Pb)₂Sr₂Ca₂Cu₃O_8+x tapes sheathed with Ag or Ag-Au alloy. The κ(T) of the tape sheathed with Ag (residual resistance ratio (RRR) = 15) decreases with decreasing temperature and starts to increase rapidly below 60 K, with a maximum at around 15 K. On the other hand, the κ(T) of the tape sheathed with Ag-5.4 wt%Au alloy has a very low value that decreases monotonically with decreasing temperature. At around 77 K, the absolute values of κ(T) for both tapes were about and , respectively. The κ(T) of a stacked sample, in which six DI-BSCCO tapes sheathed with Ag are soldered, was also measured. The measured κ(T) was fairly well reproduced by the estimated κ(T), which was calculated using the measured κ(T) of the single tape and solder.     

Symbolic computation and construction of soliton-like solutions to the (2 + 1)-dimensional dispersive long-wave equations

By means of a new Riccati equation expansion method, we consider the (2 + 1)-dimensional dispersive long-wave equations , η_t+(uη+u+u_xy)_x=0. As a result, we not only can successfully recover the previously known formal solutions obtained by known tanh function methods but also construct new and more general formal solutions. The solutions obtained include the nontravelling wave and coefficient functions’ soliton-like solutions, singular soliton-like solutions, triangular functions solutions.     

Synthesis and characterization of a new organic dihydrogenomonophosphate [3,5-(CH3O)2C6H3NH3]2(H2PO4)2

Chemical preparation, crystal structure, calorimetric studies and spectroscopic investigation are given for a new organic cation dihydrogenomonophosphate [3,5-(CH₃O)₂C₆H₃NH₃]₂(H₂PO₄)₂. This compound is triclinic with the following unit cell parameters: a=9.030(6) Å, b=16.124(5) Å, c=8.868(3) Å, α=75.04(3)°, β=110.71(4)°, γ=104.61(1)°, Z=4, V=1148.0(1) Å³, Z=2 and ρ_cal.=1.454 g cm⁻³. Crystal structure was solved and refined to R=0.04, 2752 independent reflections. The atomic arrangement can be described as inorganic layers of H₂PO₄⁻ anions parallel to planes, between which are located the organic groups. Solid-state and MAS-NMR spectroscopies are in agreement with the X-ray structure. Ab initio calculations allow the attribution of the phosphorous and carbon signals to the independent crystallographic sites and to the various atoms of the organic groups.