Université de Fribourg

Dehydroxylation kinetics of the serpentine group mine

Trittschack, Roy ; Grobéty, Bernard (Dir.)

Thèse de doctorat : Université de Fribourg, 2013 ; Nr. 1795.

Chemical reactions in general and solid-state reactions in particular are controlled by thermodynamics and kinetics. Whereas thermodynamic rules are used to state whether a phase is stable under a specific set of intensive and extensive parameters or not, kinetics applied to an underlain reaction of interest decipher the time-scale of such a reaction by offering the chance to determine associated...

Université de Fribourg

Kinetics of the chrysotile and brucite dehydroxylation reaction: a combined non-isothermal/isothermal thermogravimetric analysis and high-temperature X-ray powder diffraction study

Trittschack, Roy ; Grobéty, Bernard ; Brodard, Pierre

In: Physics and Chemistry of Minerals, 2014, vol. 41, no. 3, p. 197–214

The dehydroxylation reactions of chrysotile Mg₃Si₂O₅(OH)₄ and brucite Mg(OH)₂ were studied under inert nitrogen atmosphere using isothermal and non-isothermal approaches. The brucite decomposition was additionally studied under CO₂ in order to check the influence of a competing dehydroxylation/carbonation/decarbonisation reaction on the reaction kinetics. Isothermal experiments...

Université de Fribourg

The dehydroxylation of chrysotile: A combined in situ micro-Raman and micro-FTIR study

Trittschack, Roy ; Grobéty, Bernard

In: American Mineralogist, 2013, vol. 98, no. 7, p. 1133–1145

One of the most important mechanisms releasing water in subducting slabs of oceanic crust is connected to the dehydration of serpentinized oceanic rocks. This study reports on a detailed investigation of the transition from chrysotile—an important serpentine mineral—to forsterite through the release of water.The dehydroxylation of natural chrysotile and the subsequent phase change to...

Université de Fribourg

In situ high-temperature Raman and FTIR spectroscopy of the phase transformation of lizardite

Trittschack, Roy ; Grobéty, Bernard ; Koch-Müller, Monika

In: American Mineralogist, 2012, vol. 97, no. 11-12, p. 1965-1976

A temperature-dependent in situ micro-FTIR and micro-Raman spectroscopic investigation was performed on powdered (FTIR, Raman) and single-crystal (Raman) lizardite-1T samples between room temperature and 819 °C. Between room temperature and 665 °C, the OH stretching bands shift to lower wavenumbers, demonstrating a weak expansion of the O3-H3…O2 interlayer distance. Band...

Université de Fribourg

Dehydroxylation kinetics of lizardite

Trittschack, Roy ; Grobéty, Bernard

In: European Journal of Mineralogy, 2012, vol. 24, no. 1, p. 47-57

The thermally induced dehydroxylation of lizardite and its phase transformation to forsterite were studied by high-temperature X-ray diffraction (HT-XRD), thermogravimetry (TGA) and Fourier-transformed infrared spectroscopy (FTIR). Primary sample characteristics like chemical composition and crystallographical structure were determined by combined (HR)TEM-EDX, electron-microprobe analyses...

Université de Fribourg

Lithostratigraphie und Sedimentologie der Uran-führenden Langer Heinrich Formation/Namibia = Lithostratigraphy and sedimentology of the uranium bearing Langer Heinrich formation/Namibia

Trittschack, Roy ; Borg, Gregor

In: Zentralblatt für Geologie und Paläontologie Teil 1, 2010, p. 139-156

The task of this study was the geomorphological and sedimentological identification and subdivision of various deflation surfaces and calcrete generations around the Langer Heinrich uranium mine/Namibia. Clast counting statistics offer a chance for the classification of different surfaces and the determination of particular sources. Analytical techniques comprise SWIR spectroscopy, XRD, light...