TY - CONF A1 - Menzel, Michael T1 - Fe3+.ions in solid state reactions of mechanically activated pseudo-Boehemite xerogels studied by Mössbauer-, ESR spectroscopy and Thermoanalysis T2 - International Symposium on the Industrial Application of the Mössbauer Effect (ISIAME 2008) CY - Budapest, Hungary DA - 2008-08-17 PY - 2008 AN - OPUS4-18727 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Renz, F. A1 - Zaba, C. A1 - Roßberg, L. A1 - Jung, S. A1 - Klein, M. A1 - Klingelhöfer, G. A1 - Wünsche, A. A1 - Reinhardt, S. A1 - Menzel, Michael T1 - Spin transition in heptanuclear star-shaped iron(III)-antimony(V) NCS- and CN-bridged compounds N2 - The precursor [FeIII(L)Cl] (LH2 = N,N'-bis(2'-hydroxy-benzyliden)-1,6-diamino-3-azahexane) has been prepared and Mössbauer spectroscopy assigned a high-spin (S = 5/2) state at room temperature. The precursor is combined with the bridging units [SbV(X)6]- (X = CN-, NCS-) to yield star-shaped heptanuclear clusters [(LFeIII-X)6SbV]Cl5. The star-shaped compounds are in general high-spin systems at room temperature. On cooling to 20 K some of the iron(III) centers switch to the low-spin state as indicated by Mössbauer spectroscopy, i.e. multiple electronic transitions. While the cyano-bridged complex performs a multiple spin transition the thiocyanate-compound shows no significant population at both temperatures. KW - Heptanuclear KW - High-spin molecule KW - SbV KW - Multistability KW - Multiple spin transition PY - 2009 DO - https://doi.org/10.1016/j.poly.2008.12.027 SN - 0277-5387 VL - 28 IS - 9-10 SP - 2036 EP - 2038 PB - Elsevier CY - Amsterdam [u.a.] ; Jena AN - OPUS4-19659 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Balle, P. A1 - Geiger, B. A1 - Klukowski, D. A1 - Pignatelli, M. A1 - Wohnrau, S. A1 - Menzel, Michael A1 - Zirkwa, I. A1 - Brunklaus, G. A1 - Kureti, S. T1 - Study of the selective catalytic reduction of NOx on an efficient Fe/HBEA zeolite catalyst for heavy duty diesel engines KW - SCR KW - BEA KW - Zeolite KW - Fe KW - Active sites KW - Diesel engine KW - Hydrothermal aging KW - SO2 stability PY - 2009 DO - https://doi.org/10.1016/j.apcatb.2009.06.031 SN - 0926-3373 SN - 1873-3883 VL - 91 IS - 3-4 SP - 587 EP - 595 PB - Elsevier CY - Amsterdam AN - OPUS4-19798 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Menzel, Michael T1 - Mössbauer investigations of {Fe/alumogel} systems with Fe(0)-species involved in solid state reactions T2 - 50 Years after - The Mössbauer effect today and in the future, Technische Universität CY - Munich, Germany DA - 2008-10-09 PY - 2008 AN - OPUS4-17965 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stößer, R. A1 - Feist, M. A1 - Menzel, Michael A1 - Nofz, Marianne T1 - Fe3+ ions acting as probes and agents in aggregation processes and solid-state reactions in AlO(OH)/Al2O3 matrices N2 - The fate of doped iron species during various mechanically and thermally initiated redox reactions and aggregation processes in crystalline and amorphous AlO(OH) or Al2O3 matrices was investigated. The amorphization of the matrix was performed by chemical (i.e., via sol-gel processes) or mechanochemical treatment (high-energy ball milling). Thermal analysis, coupled with mass spectrometry (TA-MS), Mössbauer spectroscopy, and electron spin resonance (ESR), was used. The TA under various gas atmospheres allowed preparing samples under a controlled temperature regime, together with a controlled gas influence. Both the effect of mechanical activation and the influence of the iron doping could be followed macroscopically via the down-shift of the peak temperature of the corundum formation. The ESR data characterize the Fe3+ ions and their interaction with the magnetic surrounding based on the fine structure parameters. The Mössbauer data allowed the characterization of the Fe(0), Fe2+, and Fe3+ species, together with providing information about their coordinative surrounding. Both methods provided general complementary spectroscopical information. Unexpectedly, (FeOx)n and (FexAl1-x)2O3 aggregates could also be detected in the range of low Fe concentrations. It was demonstrated that even in the low-level doped systems [(FexAl1-x)2O3 with x ≥ 0.01], all the essential spectroscopic phenomena occur. At higher Fe concentrations, they were discovered to be caused by magnetic and spin exchange interactions as well as by solid-state reactions during and after the mechanical activation. PY - 2010 DO - https://doi.org/10.1111/j.1551-2916.2009.03596.x SN - 0002-7820 SN - 1551-2916 VL - 93 IS - 5 SP - 1447 EP - 1456 PB - Blackwell Publishing CY - Malden AN - OPUS4-21235 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Jung, S. A1 - Renz, F. A1 - Klein, M. A1 - Menzel, Michael A1 - Boca, R. A1 - Stößer, R. T1 - Molecular switching in iron complexes bridged via tincyanides observed by Mössbauer and ESR spectroscopy N2 - The precursor [FeIII(L)Cl] (LH2 = N,N'-bis(2'-hydroxy-3'-X-benzyliden)-1,6-diamino-3-N-hexane) is a high-spin (S = 5/2) complex (with X = -CH3, -O-CH3). This precursor is combined with the bridging unit [SnIV(CN)4] to yield star-shaped pentanuclear clusters, [(L-X-FeIII)4Sn(CN)4]Cl4 57Fe-Mössbauer, 119mSn-Mössbauer, and ESR spectroscopy are used to study our samples. For X = -CH3 the 57Fe-Mössbauer data show a multiple spin transition between iron(III) in the high-spin and low-spin state. Changing the functional group from X = -CH3 to X = -O-CH3 turns the switchability off. KW - Switching iron complexes KW - Spin-transition KW - Mössbauer spectroscopy KW - ESR-spectroscopy PY - 2010 DO - https://doi.org/10.1088/1742-6596/217/1/012027 SN - 1742-6588 SN - 1742-6596 VL - 217 IS - 1 / 012027 SP - 1 EP - 6 PB - IOP Publ. CY - Bristol, UK AN - OPUS4-22561 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stößer, R. A1 - Menzel, Michael A1 - Feist, M. T1 - The fate of Fe3+ ions in the system {AlO(OH)-xerogel/Fe-compounds} after mechanical activation and different thermal treatments studied by Mössbauer, ESR spectroscopy and thermal analysis KW - Mössbauer KW - ESR KW - Thermal analysis KW - High energy ball milling KW - Activation/deactivation processes KW - Local mechano-chemical reactions KW - Heterogeneous redox reactions PY - 2009 DO - https://doi.org/10.1007/s10751-009-9920-0 SN - 0304-3843 SN - 1572-9540 VL - 190 IS - 1-3 SP - 43 EP - 49 PB - Kluwer CY - Dordrecht AN - OPUS4-19478 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stößer, R. A1 - Menzel, Michael A1 - Feist, M. A1 - Nofz, Marianne A1 - Renz, F. T1 - Competing redox reactions in Fe-containing AlO(OH) and Al2O3 matrices: A combined investigation by Mössbauer, ESR spectroscopy and thermal analysis N2 - The investigation of iron-doped AlO(OH)/Al2O3 systems revealed that the combined employment of Mössbauer and ESR spectroscopies together with thermal analysis yields meaningful data with complementary information. This mutual complementarity is based on the coexistence of Fe point defects with the corresponding aggregated FeOx species which has been observed even for very low Fe concentrations. Competing redox processes between the dopant, the AlOx matrix, and the gas atmosphere during the thermal treatment enable the generation of solid phases exhibiting specific chemical properties. The entire reaction process is influenced by a specific mechanical and thermal pre-treatment that affects predominantly oxydative processes in the matrix. A protecting influence of the matrix preventing further reductive attack of the Fe3+ Fe2+ ions by hydrogen has been established. KW - Mössbauer KW - ESR spectroscopy KW - Thermal analysis KW - Al2O3 KW - Magnetite KW - Fe(0) KW - Fe(2+) KW - Fe(3+) PY - 2010 UR - http://iopscience.iop.org/1742-6596/217/1/012028/pdf/1742-6596_217_1_012028.pdf DO - https://doi.org/10.1088/1742-6596/217/1/012028 SN - 1742-6588 SN - 1742-6596 VL - 217 IS - 1 SP - 012028-1 - 012028-5 PB - IOP Publ. CY - Bristol, UK AN - OPUS4-21876 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Maltsev, Yuri A1 - Maltsev, S. A1 - Menzel, Michael A1 - Rogozev, B. A1 - Silvestrov, A. T1 - Two-Dimensional Mössbauer Spectra N2 - To decrease the spectra measurement time in Mössbauer spectroscopy a new data acquisition system was proposed, which allows to collect data as a two-dimensional distribution. KW - Data acquisition KW - Signal processor KW - Two-dimensional Mössbauer spectrum PY - 2004 DO - https://doi.org/10.1023/B:HYPE.0000043204.05421.b5 SN - 0304-3843 SN - 1572-9540 VL - 156/157 SP - 27 EP - 30 PB - Kluwer CY - Dordrecht AN - OPUS4-4578 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mehner, Hartmut A1 - Menzel, Michael A1 - Nofz, Marianne T1 - Laboratory Intercomparison on the Determination of the Fe(II)/Fe(III) Ratio in Glass Using Mössbauer Spectroscopy N2 - The Mössbauer community all over the world was given the opportunity to determine the Fe(II)/Fe(III) ratio in 4 glass samples of different total iron content, to classify themselves with respect to their measurement technique and especially to their kind of evaluation. KW - Mössbauer spectroscopy KW - Iron KW - Glass KW - Intercomparison KW - Fe(II)/Fe(III) ratio PY - 2004 DO - https://doi.org/10.1023/B:HYPE.0000043252.55048.63 SN - 0304-3843 SN - 1572-9540 VL - 156-157 SP - 347 EP - 352 PB - Kluwer CY - Dordrecht AN - OPUS4-4579 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lawaczeck, R. A1 - Menzel, Michael A1 - Pietsch, H. T1 - Superparamagnetic iron oxide particles: contrast media for magnetic resonance imaging N2 - The mainstream magnetic iron oxide particles used as contrast media for magnetic resonance (MR) imaging are composed of a magnetic iron oxide core surrounded by a dextran or carboxydextran coat. The core size ranges from 2 nm to less than 10 nm, and the hydrodynamic diameter ranges from 20 nm to about 120 nm. The coat prevents aggregation and sedimentation of the particles in aqueous solutions, achieves high biological tolerance, and prevents toxic side effects. Two kinds of particles are considered: (i) large particles (>30 nm), called superparamagnetic iron oxide particles (SPIOs) for liver imaging; (ii) smaller particles (<30 nm hydrodynamic diameter), called ultrasmall SPIOs (USPIOs), e.g. for MR angiography. To characterize the particles, Mössbauer spectra are presented for the two particle ensembles. These spectra allow insight into the magnetic coupling, the valency of the iron ions and a rough estimate of the core size to be deduced. On the basis of the concentration dependence of the MR signal intensities, two applications are discussed together with two representative clinical examples. KW - Superparamagnetic KW - Iron oxide particles KW - MR imaging KW - Contrast media PY - 2004 DO - https://doi.org/10.1002/aoc.753 SN - 0268-2605 SN - 1099-0739 VL - 18 SP - 506 EP - 513 PB - Longman CY - Harlow AN - OPUS4-4580 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Menzel, Michael T1 - Erste Erfahrungen mit dem RICON Konversionselektronendetektor T2 - VIIIth Mössbauer Colloquium Freiberg ´96 CY - Freiberg, Germany DA - 1996-09-30 PY - 1996 AN - OPUS4-6223 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Menzel, Michael T1 - Identifizierung verschiedener Zinnphasen in PdSn-Katalysatoren T2 - IXth Mössbauer Colloquium Freiberg ´98 CY - Freiberg, Germany DA - 1998-09-28 PY - 1998 AN - OPUS4-6227 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Menzel, Michael T1 - Characterization of PdSn-catalysts for nitrate removal in drinking water processing T2 - ICAME `99 Conference CY - Garmisch-Partenkirchen, Germany DA - 1999-08-29 PY - 1999 AN - OPUS4-6229 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Menzel, Michael T1 - Investigation of iron species in zeolite catalysts by Mössbauer spectroscopy T2 - 5th Seeheim Workshop on Mössbauer Spectroscopy CY - Seeheim-Jugenheim, Germany DA - 2002-05-21 PY - 2002 AN - OPUS4-6234 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Maltsev, Yuri A1 - Mehner, Hartmut A1 - Menzel, Michael A1 - Maslova, Natalija A1 - Rogozev, B. A1 - Kruglov, E. ED - Thomas, M. ED - Williams, J. ED - Gibb, T. T1 - Baseline investigation in transmission Mössbauer spectroscopy using resonance detectors T2 - 26th International Conference on the Applications of the Mössbauer Effect (ICAME 2001) CY - Oxford, England, UK DA - 2001-09-02 KW - Mössbauer spectroscopy KW - Resonance detector KW - Rayleigh scattering of Mössbauer radiation PY - 2003 SN - 1-402-01087-7 SN - 0304-3843 VL - 5 SP - 9 EP - 12 PB - Kluwer Acad. Publ. CY - Dordrecht AN - OPUS4-6930 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kasten, C. A1 - Carl, G. A1 - Mehner, Hartmut A1 - Menzel, Michael A1 - Rüssel, C. T1 - Polyvalent Ions - Their Behaviour in the Glass Melt and their Influence on Glass Crystallisation KW - Polyvalent Ions KW - Redox State KW - Mössbauer Spectroscopy KW - Glass Crystallisation KW - Microstructure PY - 1998 SN - 1021-6138 VL - 5-6 SP - 555 EP - 558 PB - Trans Tech Publ. CY - Aedermannsdorf AN - OPUS4-6931 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mehner, Hartmut A1 - Menzel, Michael A1 - Berndt, H. A1 - Claus, P. T1 - Mössbauer studies of platinum and rhodium catalysts promoted by tin T2 - International Conference on Applications of the Mössbauer Effect (ICAME '97) ; in memoriam of Professor Jacques CY - Rio de Janeiro, Brazil DA - 1997-09-14 PY - 1998 SN - 0304-3843 SN - 1572-9540 VL - 113 IS - 1-4 SP - 92 EP - 95 PB - Kluwer CY - Dordrecht AN - OPUS4-6932 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Menzel, Michael T1 - Superparamagnetische Eisenoxidpartikel als Kontrastmittel für die MR Diagnostik T2 - Workshop des MPI für Kohlenforschung CY - Mülheim an der Ruhr, Germany DA - 2003-06-25 PY - 2003 AN - OPUS4-3751 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Menzel, Michael T1 - Glass Laboratory Intercomparison using Mössbauer Spectroscopy T2 - 27th International Conference on the Applications of the Mössbauer Effect (ICAME 2003) CY - Muscat, Oman DA - 2003-09-21 PY - 2003 AN - OPUS4-4885 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Maltsev, Y. A1 - Mehner, Hartmut A1 - Menzel, Michael A1 - Rogozev, B. T1 - Precision in Mössbauer Spectroscopy N2 - In this paper the factors which are responsible for precision and reliability of the experimental data are discussed. The detectors of different types are compared with respect to the precision of the final results. It is shown that the use of resonance detectors gives the best results in most cases of the Sn-119m Mössbauer spectroscopy. The estimation of spectral line distortion caused by a short distance between source and detector is presented. Different procedures of velocity scale calibration are discussed. It has to be underlined that Kuprijanov's method of the velocity scale calibration gives the most reliable and fast results. T2 - 5th International Symposium on the Industrial Applications of the Mössbauer Effect (ISIAME) CY - Virginia Beach, VA, USA DA - 2000-08-13 PY - 2002 DO - https://doi.org/10.1023/A:1021203718759 SN - 0304-3843 SN - 1572-9540 VL - 139-140 IS - 1-4 SP - 679 EP - 684 PB - Kluwer CY - Dordrecht AN - OPUS4-2257 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heinrich, F. A1 - Schmidt, C. A1 - Löffler, E. A1 - Menzel, Michael A1 - Grünert, W. T1 - Fe-ZSM-5 Catalysts for the Selective Reduction of NO by Isobutane - The Problem of the Active Sites N2 - Relations between the structure of Fe–ZSM-5 catalysts prepared by interaction of FeCl3 with H–ZSM-5 and their catalytic behavior in the SCR of NO by isobutane were investigated by combining results of catalytic studies (1000 ppm NO, 1000 ppm isobutane, and 2% O2 in He, 30,000 h-1) and of physicochemical characterization (XRD, EXAFS, Mössbauer spectroscopy, TPR, IR, XPS). By variation of the preparation conditions (method of FeCl3 introduction—chemical vapor deposition or solid-state ion exchange, washing intensity, calcination regime) and of the matrix (H–ZSM-5 with normal and high defect density), Fe–ZSM-5 materials with strongly varying properties (aggregation degree of the Fe phase, acidity) were obtained. Significant discrepancies between conclusions derived from EXAFS, TPR, and Mössbauer spectroscopy were ascribed to a preference of Mössbauer spectroscopy for the detection of aggregated phases and a high defectivity of Fe oxide clusters formed upon calcination. The critical step for the preparation of a highly disperse Fe phase is extensive washing after Fe introduction. The catalytic behavior of overexchanged Fe–ZSM-5 materials prepared by interaction of FeCl3 with H–ZSM-5 of normal defect density was not influenced by aggregation of a significant part of the Fe phase. The comparison of their catalytic properties with those of a Fe2O3/H–ZSM-5 mechanical mixture and of catalysts prepared by aqueous ion exchange or by CVD of FeCl3 into H–ZSM-5 of high defect density implies that the particular activity of overexchanged Fe–ZSM-5 arises from minority sites. In these, the Fe ions are probably isolated. Other Fe sites of low nuclearity appear to add to the activity. The poor SCR performance (at a given ability for isobutane activation) of Fe–ZSM-5 prepared with a defective ZSM-5 matrix may indicate that the Fe sites which provi de the particular activity of overexchanged Fe–ZSM-5 require the cooperation of acidic sites. KW - deNOx KW - Hydrocarbons KW - Isobutane KW - Fe-ZSM-5 KW - EXAFS KW - Mössbauer spectroscopy KW - Temperature-programmed reduction PY - 2002 DO - https://doi.org/10.1006/jcat.2002.3775 SN - 0021-9517 SN - 1090-2694 VL - 212 SP - 157 EP - 172 PB - Acad. Press CY - San Diego, Calif. AN - OPUS4-2258 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmauke, T. A1 - Menzel, Michael A1 - Roduner, E. T1 - Magnetic properties and oxidation state of iron in bimetallic Pt-Fe/KL zeolite catalysts N2 - In view of an understanding of catalytic efficiency the electronic and magnetic state of iron in Fe/KL and the influence of Pt on these properties in Pt-Fe/KL were investigated by superconducting quantum interference device (SQUID) magnetization measurements and Mössbauer spectroscopy. After calcination in air, iron is present only as Fe3+ ions in both samples, mainly in a paramagnetic state. There is also a small antiferromagnetic contribution, probably due to iron oxide and hydroxide particles which precipitate on the outer surface of the zeolite crystallites during preparation. After reduction in H2, the behavior of both samples is predominantly superparamagnetic, but the presence of Pt increases both the saturation magnetization and the size of the residual hysteresis loop. At the same there remains a pronounced paramagnetic contribution which appears to be even slightly higher than before reduction. The interpretation is that alloy particles of metallic Pt–Fe are formed on the outer surface. Since small clusters inside the zeolite crystallites are most active for catalysis the alloy formation seems to be not of relevance for an enhancement of sulfur resistance. It was also shown that during reduction a fraction of Fe2+ is formed. The coordination of the Fe2+ ions is clearly influenced by Pt and it seems very likely that Fe2+ ions are in close contact with Pt clusters. This interaction is probably the origin of the enhanced sulfur resistance and catalytic activity in the reforming reactions. KW - Pt-Fe/KL zeolite KW - SQUID magnetization measurements KW - Mössbauer spectroscopy KW - Oxidation state of iron KW - Pt-Fe alloy PY - 2003 DO - https://doi.org/10.1016/S1381-1169(02)00522-8 SN - 1381-1169 SN - 1873-314X VL - 194 SP - 211 EP - 225 PB - Elsevier CY - Amsterdam AN - OPUS4-2296 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -