Müller, Jan (2018)
This thesis has been devoted to the high pressure (HP) and high temperature (HT) effects on the FeCO3-MgCO3 and the CaCO3-MgCO3 solid solution series. In more detail, I have investigated the vibrational behavior of the FeCO3-MgCO3 solid solution series under HP/HT conditions across the electronic high spin (HS) to low spin (LS) transition up to 60 GPa and 700 K and I have furthermore determined...Dissolution-precipitation reactions in the system Al2O3-SiO2-H2O and the formation of Al2SiO5
Schultze, Dina (2018)
The study of mineral replacement reactions can provide detailed insight into chemical processes, if experimental simulation and natural observation are combined. Among all chemical systems, the Al2O3-SiO2-H2O is one of the most intensely studied but some of our knowledge about it is still inconsistent. Especially problematic is the inhibited reaction of corundum and quartz to Al2SiO5 polymorphs...Dissolution behaviour of beryl
Kurumathoor Parameshwaran, Raji (2016)
Beryl, a cyclosilicate, with an ideal chemical composition Be3Al2Si6O18, is the most important accessory Be mineral and an ore of the strategic element Be. It is mainly found in pegmatites, in some highly evolved granites and in some metamorphic rocks. In many cases, the beryl forming process extends over a wide range of P-T-X conditions. This process represents the major range of pegmatitic fo...Structure of the catalytic sites in Fe/N/C-catalysts for O-2-reduction in PEM fuel cells
Kramm, Ulrike I. ; Herranz, Juan ; Larouche, Nicholas ; Arruda, Thomas M. ; Lefèvre, Michel ; Jaouen, Frédéric ; Bogdanoff, Peter ; Fiechter, Sebastian ; Abs-Wurmbach, Irmgard ; Mukerjee, Sanjeev ; Dodelet, Jean-Pol (2012)
Fe-based catalytic sites for the reduction of oxygen in acidic medium have been identified by 57Fe Mössbauer spectroscopy of Fe/N/C catalysts containing 0.03 to 1.55 wt% Fe, which were prepared by impregnation of iron acetate on carbon black followed by heat-treatment in NH3 at 950 °C. Four different Fe-species were detected at all iron concentrations: three doublets assigned to molecular FeN4-...