Epitaxial hard magnetic SmCo5 MFM tips - a new approach to advanced magnetic force microscopy imaging.

Cantilever based scanning force sensors, which probe a specific tip-sample interaction through a functional tip coating, are limited by the material performance achievable in the coating process. In case of the wide spread magnetic force microscopy (MFM) technique, the magnetic performance of MFM tips, especially the response to magnetic fields and the coercivity, fall far behind the quality known from permanent magnet films prepared with optimized process conditions on appropriate substrates. We resolve this limitation by starting from an optimized thin film architecture - a highly anisotropic SmCo5 film grown epitaxially on MgO(110) substrates - from which a tip is separated by focused ion beam and is attached to a cantilever. Not compromising on resolution and sensitivity, we demonstrate an unrivaled rigidity in magnetic fields, which will largely advance quantitative microscopic investigation of magnetic materials with strong stray fields and allows MFM measurements in external magnetic fields of currently up to 0.7 T. The material optimization for a specific sample - cantilever interaction without restrictions in substrate, film architecture, film preparation conditions and tip shape, is not limited to MFM but offers new opportunities also for other scanning force microscopy modes.

The use of EAF dust in cement composites: assessment of environmental impact.

Electric arc filter dust (EAF dust) is a waste by-product which occurs in the production of steel. Instead of being disposed of, it can be used in cement composites for civil engineering, and for balances in washing machines. To estimate the environmental impact of the use of EAF dust in cement composites leachability tests based on diffusion were performed using water and salt water as leaching agents. Compact and ground cement composites, and cement composites with addition of 1.5% of EAF dust by mass were studied. The concentrations of total Cr and Cr(VI) were determined in leachates over a time period of 175 days. At the end of the experiment the concentrations of some other metals were also determined in leachates. The results indicated that Cr in leachates was present almost solely in its hexavalent form. No leaching of Cr(VI) was observed in aqueous leachates from compact cement composites and compact cement composites to which different quantities of EAF dust have been added. In ground cement composites and in ground cement composites with addition of EAF dust, Cr(VI) was leached with water in very low concentrations up to 5 microg L(-1). Cr(VI) concentrations were higher in salt water leachates. In compact and ground cement composites with addition of EAF dust Cr(VI) concentrations were 40 and 100 microg L(-1), respectively. It was experimentally found that addition of EAF dust had almost no influence on leaching of Cr(VI) from cement composites. Leaching of Cr(VI) originated primarily from cement. Leaching of other metals from composites investigated did not represent an environmental burden. From the physico-mechanical and environmental aspects EAF dust can be used as a component in cement mixtures.