TY - JOUR A1 - Stößer, R. A1 - Feist, M. A1 - Patzwaldt, K. A1 - Menzel, Michael A1 - Emmerling, Franziska ED - Brooks, H. T1 - Redox reactions of K3[Fe(CN)6] during mechanochemically stimulated phase transitions of AlOOH N2 - Thermally induced redox reactions of K3[Fe(CN)6] (1) were investigated for a broad temperature range by thermal methods and structure analytical methods (ESR and Mößbauer spectroscopy, X-ray Powder diffraction and XANES). Based on the influence of the mechanically activated and transforming matrices 2 and 3, redox processes can be tuned to form doped Al2O3 systems which contain either isolated Fe3+ centres or redox active phases and precursors like (Al1-xFex)2O3 (4), (Al3-xFex)O4 (5), Fe3O4, Fe2O3 and Fe0. The phase Fe3C and the chemically reactive C-species were detected during the reaction of 1. The final composition of the doped products of α-Al2O3 is mainly influenced by the chemical nature of the Fe doping component, the applied temperature and time regime, and the composition of the gas phase (N2, N2/O2 or N2/H2). From the solid state chemistry point of view it is interesting that the transforming matrix (2 and 3) possesses both oxidative and protective properties and that the incorporation of the Fe species can be performed systematically. KW - A. Inorganic compounds KW - C. Mössbauer spectroscopy KW - C. Thermogravimetric analysis KW - D. Electron paramagnetic resonance KW - ESR-Spektroskopie KW - Kaliumhexacyanoferrat(III) KW - Mechanische Aktivierung KW - Mößbauer-Spektroskopie KW - Redoxreaktionen KW - TA-MS-Messungen PY - 2011 DO - https://doi.org/10.1016/j.jpcs.2011.03.016 SN - 0022-3697 VL - 72 IS - 6 SP - 794 EP - 799 PB - Pergamon Press CY - New York, NY AN - OPUS4-23685 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stößer, R. A1 - Feist, M. A1 - Willgeroth, Carola A1 - Emmerling, Franziska A1 - Menzel, Michael A1 - Reuther, H. T1 - The 'quiet Goldschmidt' - a mechanochemical, thermoanalytical, and spectroscopic study of selected steps of the aluminothermic reaction N2 - The Goldschmidt reaction (2Al+α-Fe2O3) was investigated both under mechanical and thermal activation by employing a combination of analytical methods such as ESR and Mössbauer spectroscopy, magnetic susceptibility, X-ray powder diffraction, and thermal analysis (TA). Both the mechanical treatment and the TA runs under air caused the reaction conditions of 'quiet redox reactions' due to a retarding effect and enabled a reaction study in a 'slow motion mode'. This allowed to establish distinct partial steps of the integral reaction process depending on the intensity of the mechanical impact, the educt composition, the gas phase composition, and, finally, the thermal excitation in the TA runs. Particular attention was payed to the role of the gas phase and to the reaction of aluminum with differently activated oxygen species. The phlegmatizing effect was traced back to the formation of Al2O3 coverages of the Al particles. KW - Thermite reaction KW - Iron ESR and Mössbauer spectroscopy KW - Mechanochemical activation KW - Magnetic moments KW - DTA-TG KW - XRD PY - 2013 DO - https://doi.org/10.1016/j.jssc.2013.02.032 SN - 0022-4596 SN - 1095-726X VL - 202 SP - 173 EP - 190 PB - Elsevier CY - San Diego, Calif. AN - OPUS4-29528 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -