Key Engineering Materials Vols. 675-676

Abstract: Nanostructure silver films were obtained by dc magnetron sputtering at room temperature. The influences of deposition time on the morphology and optical properties were studied by field-emission scanning electron microscope and UV-vis NIR spectrophotometer. It was found that the optical properties of the nanostructure silver film can be effect by surface morphology. The surface enhanced Raman scattering activities of nanostructure Ag films were demonstrated by methylene blue (MB) as probing molecules while the detection limit of MB was found to be as low as 10^-5 M from this SERS substrate.

Abstract: Nanostructure TiO₂ films were prepared by electron beam evaporation with glancing angle deposition technique at room temperature. The morphology, crystal structure and optical properties at various substrate rotation speeds (0-10 rpm) were investigated by field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and UV-vis spectrophotometer. The cross-section FE-SEM images illustrate that the nanostructures consist of different morphology: slanted columnar, spiral and vertical align nanorods at 0, 0.01 and 10 rpm-rotation speed, respectively. In particular, the rotation speed-controlled incoming vapor flux was found to play crucial role in the growth of nanostructure TiO₂ films.

Abstract: The MgO nanowire growth on Al₂O₃ lamellae has been placed on plasma-sprayed process. The chemical compositions of nanocomposite powders were appeared α-Al₂O₃ and cubic-MgO phases. After deposited by plasma sprayed coating, the chemical composition has presented major of γ-Al₂O₃, minor of α-Al₂O₃ and cubic-MgO phases. The microstructure of Al₂O₃/13wt%MgO coating was exhibited high density and good distribution of MgO lamellae with thickness in range 241 μm. The MgO nanowire had dispersion that width diameter in range of ~96.5 nm and average of length 884.9 nm, on the Al₂O₃ lamellae. The result of nanostructure MgO nanowire generation could be explained that the MgO clusters have been depressed on the Al₂O₃ lamella at the low temperature zone, then deposited and nucleated in during plasma-sprayed. It was found that the new phase of spinel Al₂MgO₄ form interaction between Al₂O₃ and MgO. The average porosity of ∼14% was observed in Al₂O₃/13wt%MgO nanocomposite coating.

Abstract: The YBa₅Cu₆O_x (Y156) superconductors were synthesized by melt process method with sintering at 980 °C. The samples were characterized by the SEM, EDX, XRD and resistance measurement. The critical temperature onset () and the critical temperature offset () were found at 90 K and 80 K respectively. The crystal structures was orthorhombic performed by Rietveld full-profile analysis method with lattice parameter a = 3.80078 Å, b = 3.89068 Å and c = 22.94436 Å. The c/a ratio was 6.04 and the anisotropy was 2.33. The lower c/a ratio and higher anisotropic were found as increasing the sintering temperature with little change in a and b-axis value. We found that as increasing of sintering temperature, the critical temperature was decreased but the anisotropy was increased.

Abstract: Abstract. In this research, we synthesized and investigate the physical properties of YBaCuO superconductor; Y123 and Y13-20-30. The melt process was used for heat treatment of our samples. We found that the critical temperature onset of Y13-20-33 and Y123 were at 90 K and 94 K, respectively. The morphology of Y123 superconductor has flat surface and more clear grain boundary than Y13-20-33 superconductor. However, more melted of grain boundary were found on Y13-20-33. Both samples were the orthorhombic crystal structure that c/a ratio of Y13-20-33 was higher than of Y123 superconductor.

Abstract: The Y257 superconductor was prepared by the melt process. The critical temperature of the sample is lower than sample prepared by solid state reaction. The sample are composed of 60% of superconducting phase and 40% of non-superconducting phase. The superconducting phase was orthorhombic structure and Pmmm space group symmetry. The EDX mapping indicated Y, Ba, Cu and O elements intermittently distribute in the sample. The TEM measurements indicated the SAD pattern of the single crystal and the polycrystalline. The DTA measurements indicated that the onset temperature were initially observed at around 999.848°C and offset temperature at 1018.680°C. The sample show the thermal reaction with endothermic reaction.

Abstract: This research aims to investigate the effects of bismuth glass filling treatment on physical properties of natural ruby. The ruby mixed with bismuth glass powder was treated in electric furnace at 1000, 1100, 1200 and 1300°C in oxygen atmosphere for 24 hours, respectively. Each ruby before heated and after heated was determined reflective index and specific gravity. Fissure and inclusion of all samples were observed by optical microscope. The result reveals that reflective index and specific gravity of treated rubies were increased more than before treatment. Moreover, the result shows that the fissure surface on ruby was filled by glass and made clear surface.

Abstract: In this work, effects of CoO on silicoborate glasses have been investigated. Glasses were prepared in formula (53-x)B₂O₃:11SiO₂:32SrO:1Bi₂O₃:1TiO₂: xCoO (where x is 0.00, 0.01, 0.02, 0.03, 0.04 and 0.05 mol%). The results show that, the density and refractive index were increased with increasing of CoO concentration. The optical absorption spectra were measured by UV-Visible Spectrophotometer and show peaks correspond with Co²⁺ in glass matrices at a wavelength of around 511 584 and 649 nm for all glass samples.

Abstract: In this work, effect of Li₂O and Na₂O on bismuth borate glasses have been investigated. The glass samples were prepared in composition 44B₂O₃ : 50Bi₂O₃ : 5Li₂O : 1A₂O₃ and 44B₂O₃ : 50Bi₂O₃ : 5Na₂O₃ : 1A₂O₃ (where A₂O₃= Sm₂O₃ and Dy₂O₃). Glasses were prepared using the melt-quenching technique at 1,100 ^oc under normal atmosphere. The result found that, the density and molar volume of lithium bismuth borate glasses are less than sodium bismuth borate glasses both in Sm₂O₃ and Dy₂O₃. In addition, the optical absorption spectra and luminescence of lithium bismuth borate glasses are higher than sodium bismuth borate glasses both in Sm₂O₃ and Dy₂O₃.

Abstract: Physical and optical properties of mixed Mn-Co ions in soda lime silicate glasses were measured and calculated. The results show that, the densities increased with the increasing of CoO content. This indicates that increasing the molecular weight of oxide ions used in the glass was due to the replacing SiO₂ by CoO. The refractive indices were increased with increasing of CoO concentration. The absorption peaks of CoO doped glasses occurred at the wavelength around 511, 584 and 649 nm which are assigned to ⁴A₂(F) ® ²A₁(G), ⁴A₂(F) ® ⁴T₁(P) and ⁴A₂(F) ® ²E(G) transition, respectively.