...Giancarlo Della Ventura; Francesco Radica; Federico Galdenzi; Umberto Susta; Gianfelice Cinque; Mariangela Cestelli-Guidi; Boriana Mihailova; Augusto Marcelli Abstract In this work, we address the kinetics of dehydrogenation occurring at high temperatures (HT) in riebeckite, a sodic amphibole...

...Małgorzata Lempart; Arkadiusz Derkowski; Tomasz Strączek; Czesław Kapusta Abstract Thermally induced dehydroxylation and oxidative dehydrogenation drive the thermal decomposition of all Fe 2+ -containing phyllosilicates. Whereas the former produces H 2 O gas, the latter results in H 2 evolution...

...Małgorzata Lempart; Arkadiusz Derkowski; Katarzyna Luberda-Durnaś; Michał Skiba; Artur Błachowski Abstract In addition to dehydroxylation, thermal decomposition of Fe(II)-bearing chlorites also involves dehydrogenation. Dehydrogenation does not require the presence of oxygen and readily occurs...

.../dehydrogenation takes place mostly in the E module (M3 and H1). Perbøeite-(Ce) derives from gatelite-(Ce) by the homovalent substitution [ M3 Fe 2+ → M3 Mg]. Alnaperbøeite-(Ce) derives from perbøeite-(Ce) or gatelite-(Ce) by the coupled heterovalent substitutions [ A Na + + 2 M3 Al 3+ → A REE + 2 M3 (Fe 2+ or Mg...

... chemistry) data. The heterogeneities revealed for some kaersutite megacrysts, when comparing bulk and EMP Fe 3+ /ΣFe results, cannot explain the differences with the EMP measurements. It is thus proposed that any EMP overestimation of Fe 3+ /ΣFe results from a beam-induced dehydrogenation and a subsequent...

...John M. Hughes; Bradley L. Jolliff; John Rakovan Abstract The atomic arrangements of two natural samples of whitlockite, a synthetic whitlockite specimen, a synthetic whitlockite specimen heated at 500 °C, and a synthetic merrillite specimen (formed through dehydrogenation of synthetic whitlockite...

... likely have resulted from dehydrogenation-oxidation of nominally anhydrous mantle olivine during rock exhumation. In view of the contrasting diffusion rates of H and Fe in the olivine lattice, it is suggested that the formation process might actually take place in steps. Hydrogen diffusion...

... oxides, but its thermal crystallization to hematite is postponed to ~500–600°C. The Fe 3+ cations in the interlayer space are much less thermally stable than Al pillars in pillared interlayered clays (PILCs). Form I is more active in oxidative dehydrogenation of propane, while form II is the active...

...-dehydrogenation. The crystal structure and the chemical composition of one crystal [ a = 13.014(5), b = 8.867(3), c = 5.838(4) Å, β = 90.02(4)°] were investigated. X-ray crystal-structure refinement, performed in the Pnam space group, and electron microprobe analyses yielded the formula (Ca 0.98 Mn 2+ 0..02 )(Fe...

... the following chemical formula: Y 0.51 REE 0.25 Th 0.15 U 4+ 0.06 Ca 0.04 ) Σ=1.01 (Ti 1.56 Nb 0.33 Ta 0.05 W 0.02 Fe 2+ 0.03 ) Σ=1.99 O 5.52 (OH) 0.48 . Upon heating the sample in air at temperatures higher than 550°C, an oxidation-dehydrogenation reaction takes place, resulting mainly in a lengthening...

... dehydrogenation in magma chambers heated from below by intrusion of mafic magma. The maximum P Δ V energy generated from dehydrogenation alone can approach 2 × 10 3 joules per kilogram of magma. This finding provides support for the concept that injection of mafic magma coupled with sudden degassing of hydrous...

... changes that result from partial oxidation-dehydrogenation in a tschermakitic hornblende. The samples examined were H-1, the natural, untreated material (Fe 3+ = 0.389 pfu); H-11, material hydrothermally annealed at 650 °C and 1 kbar for 4 d at the magnetite-hematite oxygen buffer (Fe 3+ = 0.565 pfu...

...Michael W. Phillips; Robert K. Popp; Celia A. Clowe Abstract Structural changes that accompany oxidation-dehydrogenation in amphiboles are examined using bond-length and bond-strength data from six crystal-structure refinements. These include tschermakitic hornblende (untreated; hydrothermally...

..., allowing neutralization and expulsion of hydrogen. Dehydrogenation takes place over a period on the order of an hour under the experimental conditions. Subsequent to loss of all hydrogen, continued oxidation takes place by a much slower process, possibly involving electron and/or ion diffusion. In addition...