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The influence of defect structures at reaction interfaces and shear-deformation on reaction rim growth kinetics in the MgO-Al2O3 system

2014-2017: Austrian Science Fund FWF I1704-N19
International Joint Project in the framework of the DFG-FWF funded Research Group FOR741-DACH

Principal Investigators:
Gerlinde HABLER (University of Vienna)
Rainer ABART (University of Vienna)

Postdoctoral Researchers:
Chen LI (University of Vienna)
Thomas GRIFFITHS (University of Vienna)
Lisa BALDWIN (University of Vienna)

Cooperation Partners:
Erik RYBACKI (Helmholtz-Center GFZ Potsdam)
Georg DRESEN (Helmholtz-Center GFZ Potsdam)
Lutz GÖTZE (FU Berlin)
Jannik C. MEYER (University of Vienna)
Thomas WAITZ (University of Vienna)
Petr JERABEK (Charles University Prague)
Stefan ZAEFFERER (MPIE Düsseldorf)

Abstract: Reaction rims are common features in metamorphic rocks, which form, when two solid phases that are in contact react to form a new phase at their interface. Reaction rims have been widely used in Material Sciences and Earth Sciences to infer environmental conditions and rate information from reactive systems. In depth knowledge of the underlying processes that are effective during reaction rim formation is mandatory for properly interpreting microstructures, textures and mineral compositions in rocks. We aim to identify and balance effective mechanisms that govern reaction rim growth kinetics in the synthetic system MgO- Al2O3, where MgO (periclase) and Al2O3 (corundum) react to form MgAl2O4 (spinel) under defined experimental conditions. We propose investigations that focus on two aspects of reaction rim growth: A) Atomic structures at both propagating reaction fronts will be investigated by high resolution analytical methods (SEM, TEM) in order to obtain information on the local defect structure at interfaces with defined crystallographic orientation relation of reactants and product. As we account for changes in the local defect structure during progressive reaction rim growth, we compare samples from initial growth stages with those from long-term experiment-runs. B) In addition, we investigate the effect of externally imposed deformation on the overall rim growth rate and on the microstructure and texture evolution. We intend to perform torsion experiments of single-crystal reaction-diffusion couples using a Paterson-type gas-medium apparatus. Therefrom we will obtain samples exposed to increasing finite shear-strain from the core to the rim. From microstructural and textural analyses at high spatial resolution (SEM-EBSD, SEM-FSD, (S)TEM) we intend to decipher the influence of deformation and dynamic recrystallization on the reaction progress and the microstructure and texture development. We will also analyse the phase compositions at the immediate reaction front by EMPA in order to correlate microstructures and textures with the grade of deviation from local chemical equilibrium. Previous investigations have shown that growth mechanisms and topotactic relations control the microstructure and texture of reaction rims under static conditions. Performing additional experiments in a dynamic setting is expected to accomplish the understanding of how the system responds to externally applied stress, how deformation and chemical reactions interact during phase transformation and which mechanisms underlie microstructure and texture formation during rim growth.


Publications (peer reviewed):

Li, C., Griffiths, T., Pennycook, T., Mangler, C., Jeřábek, P., Meyer, J., Habler, G., Abart, R. (2016, in press): The structure of a propagating MgAl2O4/MgO interface: Linked atomic- and µm-scale mechanisms of interface motion. Philosophical Magazine & Philosophical Magazine Letters. DOI: 10.1080/14786435.2016.1205233

Abart, R., Svoboda, J., Jeřábek, P., Povoden-Karadeniz, E., Habler, G. (2016): Interlayer growth kinetics of a binary solid-solution based on the thermodynamic extremal principle: Application to the formation of spinel at periclase-corundum contacts. American Journal of Science, 316, 309-328. DOI:10.2475/04.2016.01

Publications (abstracts / talks / posters):

Li, C. (2016) Understanding the formation and migration of corundum/spinel/periclase interfaces: a multi scale perspective from SEM-EBSD to atomic-resolution STEM. Seminar lecture in "Topics in Mineralogy", 29.04.2016, Vienna.

Li, C. (2016) Investigating corundum/spinel/periclase interface Migration in the Atomic Scale via STEM. Geo-Materials Seminar 2016, 20.-24.02.2016, Saalbach Hinterglemm, Austria.

Abart, R., Svoboda, J., Jerabek, P., Povoden-Karadeniz, E., Habler, G. (2015) Element partitioning at reaction interfaces in a reactive diffusion setting: spinel layer growth in the MgO-Al2O3 system, experiment and thermodynamic model. PTM 2015 (Whistler, BC, Canada)

Habler, G. (2015) Automated EBSD band recognition of periclase (MgO): looking for appropriate Hough-transform settings. Arbeitskreistreffen der AK EBSD (Osnabrück, Deutschland)

Habler, G. (2015) Microfabrics of mineral host-inclusion systems: constraining formation mechanisms. GeoBerlin 2015 (Berlin, Germany)

Li, C., Pennycook, T., Mangler, C., Habler, G., Abart, R., Jerabek, P., Götze, L. C. (2015) Investigating corundum/spinel/periclase interface migration in the atomic scale via Scanning Transmission Electron Microscopy. MinPet 2015 (Leoben, Austria), 10.-13.09.2015, Mitteilungen der Österreichischen Mineralogischen Gesellschaft, 161

Li, C. (2015) Spinel Growth: Understanding the atomic structure of Al2O3/MgAl2O4/MgO interface via STEM (preliminary result). Geo-Materials Seminar 2015, 21.-25.02.2015, Saalbach Hinterglemm, Austria.

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