Preparation and Characterization of TeO2 Based Glasses

Binary and ternary TeO2 based oxy-chloride glass systems have been prepared and characterised by absorption and low-temperature photoluminescence spectroscopy, and by the measurements of dc electrical conductivity. Prepared glasses exhibit transmittance 75-80% in a broad transmission range 0.3 – 6.5µm with modest shift of upper absorption edge to longer wavelength as heavier ions are introduced into the system. Electronic transitions between 4f-4f inner shells of Pr3+ ions embedded into the host glass have been investigated in a wide temperature range as a function of used precursors used for doping. The temperature dependence of dc electrical conductivity exhibits Arrhenius plots with the single activation energy. PACS codes 81.05.Kf, 78.20.Ci, 78.55.Hx

Formation of Zn-ZnO Polygon Prismatic Nanocrystals by Liquid Source via Thermal Vapor Transport

A novel hierarchical polygon prismatic nanostructure of wurtzite Zn has been grown on silicon by liquid-solution seed nucleation and vapor-gas growth method. The Zn(ClO4)2 colloidal sol with various concentrations was used as seeds to control the dimension of Zn crystals from the nanometer (30 nm) to micrometer scale (2 µm). Depending on heat-treatment temperature, different morphology was developed. In the temperature range of 200-300oC, a compact polygon prismatic Zn structure was formed. However, in a high temperature range of 300-400oC, polygon prismatic Zn with hollow structure was observed. After oxidation treatment, the ZnO surface layer can be developed on the Zn nanocrystals to form ZnO-Zn core-shell structure as evidenced from PL measurement. These formed ZnO-Zn nano- and micro-crystals can be further used as building blocks to assemble two- or three-dimensional photonic crystals. PACS codes: 81.10.Aj, 64.70.Fx, 64.72.-y