Europium-doped barium bromide iodide

Single crystals of Ba0.96Eu0.04BrI (barium europium bromide iodide) were grown by the Bridgman technique. The title compound adopts the ordered PbCl2 structure [Braekken (1932 ▶). Z. Kristallogr. 83, 222–282]. All atoms occupy the fourfold special positions (4c, site symmetry m) of the space group Pnma with a statistical distribution of Ba and Eu. They lie on the mirror planes, perpendicular to the b axis at y = ±0.25. Each cation is coordinated by nine anions in a tricapped trigonal prismatic arrangement

Hydrogen storage in carbon nanotubes and related materials

Adsorption of hydrogen at 300 K has been investigated on well-characterized samples of carbon nanotubes, besides carbon fibres by taking care to avoid many of the pitfalls generally encountered in such measurements. The nanotube samples include single- and multi-walled nanotubes prepared by different methods, as well as aligned bundles of multi-walled nanotubes. The effect of acid treatment of the nanotubes has been examined. A maximum adsorption of ca. 3.7 wt% is found with aligned multi-walled nanotubes. Electrochemical hydrogen storage measurements have also been carried out on the nanotube samples and the results are similar to those found by gas adsorption measurements

Hydrogel route to nanotubes of metal oxides and sulfates

A tripodal cholamide-based hydrogel has been employed as a template to synthesize inorganic nanotubes. Besides nanotubes of oxides such as SiO2, TiO2, ZrO2, WO3 and ZnO, nanotubes of sulfates such as the water-soluble ZnSO4 as well as of BaSO4 have been obtained using this method. An advantage of the use of the hydrogel is that metal alkoxides are not required for the synthesis of the oxide nanotubes. The nanotubes have been characterized by X-ray diffraction and transmission electron microscopy

Electrical properties of inorganic nanowire-polymer composites

Composites of nanowires of ZnO, RuO2 and Ag with polyaniline (PANI) as well as polypyrrole (PPy) have been prepared, for the first time, by an in-situ process, in order to investigate their electrical properties. Characterization by electron microscopy and IR spectroscopy indicates that there is considerable interaction between the oxide nanowires and the polymer. The room-temperature resistivity of the composites prepared in-situ varies in the 0.01-400 Ω cm range depending on the composition. While the resistivities of the PANI-ZnONW and PPy-ZnONW composites prepared by the in-situ process are generally higher than that of PANI/PPy, those of PANI-RuO2NW and PANI-AgNW are lower. Composites of ZnONW with polyaniline prepared by an ex-situ process exhibit a resistivity close to that of polyaniline

Ba11La4Br34: a new barium lanthanum bromide

The structure of the title compound, barium lanthanum bromide (11/4/34), can be derived from the fluorite structure. The asymmetric unit contains two Ba sites (one with site symmetry 4/m..), one La site (site symmetry 4..), one mixed-occupied Ba and La site (ratio 1:1, site symmetry m..) and six Br sites (one with site symmetry \=4.., one with 2.., one with m.., the latter being disordered over two positions with a 0.86:0.14 ratio). The fundamental building units of the structure are edge-sharing polyhedral clusters made up of Ba and La bromide clusters inter­connected to BaBr8 square prisms and BaBr10 groups

Scintillation Properties of Eu2+-Activated Barium Fluoroiodide

The scintillation properties of powders and single-crystals of BaFI doped with Eu2+ are presented. Single crystals were grown by the vertical Bridgman technique. Under optical and X-ray excitation, the samples exhibit a narrow E2+ 5d-4f transition emission centered at 405 nm. The scintillation light output is estimated to be 55,000+-5,000 photons/MeV at 662 keV with 85percent of the light decaying within 600 ns. An energyresolution of 8.5percent full width at half maximum (FWHM) has been achieved using this scintillator for 662 keV excitation (137Cs source) at room temperature

Europium-doped barium bromide iodide

Single crystals of Ba0.96Eu0.04BrI (barium europium bromide iodide) were grown by the Bridgman technique. The title compound adopts the ordered PbCl2 structure [Braekken (1932). Z. Kristallogr. 83, 222-282]. All atoms occupy the fourfold special positions (4c, site symmetry m) of the space group Pnma with a statistical distribution of Ba and Eu. They lie on the mirror planes, perpendicular to the b axis at y = +-0.25. Each cation is coordinated by nine anions in a tricapped trigonal prismatic arrangement

Scintillation Properties of Eu2+-Activated Barium Fluoroiodide

The scintillation properties of powders and single-crystals of BaFI doped with Eu2+ are presented. Single crystals were grown by the vertical Bridgman technique. Under optical and X-ray excitation, the samples exhibit a narrow E2+ 5d-4f transition emission centered at 405 nm. The scintillation light output is estimated to be 55,000+-5,000 photons/MeV at 662 keV with 85percent of the light decaying within 600 ns. An energy resolution of 8.5percent full width at half maximum (FWHM) has been achieved using this scintillator for 662 keV excitation (137Cs source) at room temperature

Scanning tunneling microscopy and spectroscopy of Se and Te nanorods

Se and Te nanorods obtained by a self-seeding solution growth process have been examined by scanning tunneling microscopy and spectroscopy(STM/STS). The diameters of the rods, as revealed by STM images were in the range of 1060 nm, with aspect ratios of 10-20. The I-V data of the Se and Te nanorods exhibit band gaps of similar to 1.3 and similar to 0.4 eV, respectively, nearly independent of the diameter, and these values are close to the bulk values of Se and Te. In both the cases,the nanorods possess a small but finite conductance even in the bandgap regions, the conductance value increasing with the diameter of the rod. A tunneling mechanism involving the surface states is proposed to explain this phenomenon