Colossal Electric Conductivity in Ag-defect Ag5Pb2O6

Bystroem-Evers compound Ag5 Pb2O6 has been annealed at 500-540 K under flow of electric current which results in a textured structure and anisotropic colossal electric conductivity (> 10^9 ohm-1cm-1) between 210-525 K. The related physical properties are primarly governed by dissociation of Ag from c-axis channels and lattice strains which in turn depend upon electric current.Comment: 13 pages, 7 figure

Mobility of metals and metalloids from SHOS coal ash and slag deposit: mineralogical and geochemical constraints

Deposits remained after coal combustion are a well-known occurrence in the world; unfortunately, only a small percentage of such deposits are adequately regulated and, consequently, pose a serious threat to the local environment. Attenuation of negative consequences presupposes knowledge of a number of features, both of the deposit and the local environment as well the interaction with local biota. In this study, unregulated waste generated from decades of coal mining and combustion of superhigh-organic-sulfur Rasa coal, enriched in Se-U-Mo-V and located in a vulnerable karst region, was investigated. To assess the impact of landfill on the environment, in addition to its general geochemical and mineralogical features, the human health risk was assessed and the leaching of elements from the landfill, local soil, and the coal itself was investigated. For the latter, three extraction procedures, ASTM, EP, and TCLP (pH 4.93 and 2.9), were employed, mimicking different environmental conditions, including the sporadic occurrence of acid rains in the region. The soil around the landfill displayed enrichment in the majority of elements compared to expected values, with exception of Se, Mo, U, V, Sr, and Cu found at the highest levels in landfill samples. Mobility of elements was found to be controlled by both pH and mineralogy (carbonates and sulfates), whereby the overall highest relative mobility was observed in landfill samples for elements prevalently bound to sulfate phases. Calculated Hazard Quotient describes this landfill as a risk to the environment and human health through different pathways

A round robin characterisation of the thickness and composition of thin to ultra-thin AlNO films

International audienceA round robin characterisation of the thickness and composition of thin to ultra-thin AINO films was organised. Thirteen participant groups used various ion beam analysis (IBA) techniques to determine quantitatively the thickness, areal density and concentration of aluminium, nitrogen and oxygen in films with thicknesses ranging nominally from 1 to 100 nm. Most of the ratios reported are not statistically different from the reference values, and only very seldom are large deviations observed. It was not possible to identify a given technique or a group of techniques as being more reliable for analysing the ultra-thin samples. Unexpected deviations in some results reflect a need for further measurements of fundamental quantities, namely cross-sections and stopping powers in energy ranges useful for IBA. Furthermore, precise measurements of beam fluence and detector solid angle would lead to improvements in the accuracy of some of the quantities reported, particularly areal densities. (C) 2004 Elsevier B.V. All rights reserved