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| Naji, M. |
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| Motta, Antonella |
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| Aletan, Dirar |
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| Mohamed, Tarek |
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| Ertürk, Emre |
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| Taccardi, Nicola |
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| Kononenko, Denys |
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| Petrov, R. H. | Madrid |
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| Alshaaer, Mazen | Brussels |
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| Bih, L. |
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| Casati, R. |
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| Muller, Hermance |
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| Kočí, Jan | Prague |
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| Šuljagić, Marija |
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| Kalteremidou, Kalliopi-Artemi | Brussels |
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| Azam, Siraj |
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| Ospanova, Alyiya |
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| Blanpain, Bart |
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| Ali, M. A. |
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| Popa, V. |
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| Rančić, M. |
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| Ollier, Nadège |
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| Azevedo, Nuno Monteiro |
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| Landes, Michael |
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| Rignanese, Gian-Marco |
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Jones, Anthony
in Cooperation with on an Cooperation-Score of 37%
Topics
Publications (20/20 displayed)
- 2021BEDE: Bayesian estimates of dust evolution for nearby galaxiescitations
- 2015Amorphous Hydrocarbon Optical Properties
- 2015Dust variations in the diffuse interstellar medium: constraints on Milky Way dust from Planck-HFI observationscitations
- 2014A hidden reservoir of Fe/FeS in interstellar silicates?citations
- 2013The Circle of Dust: From Nanoparticles to Macromolecules and Beyond
- 2013Heteroatom-doped hydrogenated amorphous carbons, a-C:H:X. "Volatile" silicon, sulphur and nitrogen depletion, blue photoluminescence, diffuse interstellar bands and ferro-magnetic carbon grain connectionscitations
- 2013On the Excitation and Formation of Circumstellar Fullerenes
- 2013Photoprocessing-driven dust evolution in the diffuse ISM
- 2012Variations on a theme - the evolution of hydrocarbon solids. I. Compositional and spectral modelling - the eRCN and DG modelscitations
- 2012Variations on a theme - the evolution of hydrocarbon solids. II. Optical property modelling - the optEC<SUB>(s)</SUB> modelcitations
- 2012Variations on a theme - the evolution of hydrocarbon solids. III. Size-dependent properties - the optEC<SUB>(s)</SUB>(a) modelcitations
- 2009The Cycle of Carbon Dust in the ISM
- 2008Carbonaceous dust in interstellar shock waves: hydrogenated amorphous carbon (a-C:H) vs. graphitecitations
- 2007IRAS 08572+3915: constraining the aromatic versus aliphatic content of interstellar HACscitations
- 2007Ferromagnetic inclusions in silicate thin films: insights into the magnetic properties of cosmic grainscitations
- 2006The origin of GEMS in IDPs as deduced from microstructural evolution of amorphous silicates with annealingcitations
- 2004Laboratory Studies of the Ion-irradiation of Dust Analogs: Application to the Evolution of Interstellar Silicates
- 2002Temperature-dependent FIR/sub-mm dust emissivity indices: some implications for the diffuse ISM dust compositioncitations
- 2001Structural and chemical alteration of crystalline olivine under low energy He<SUP>+</SUP> irradiationcitations
- 2000The formation and reformation of interstellar dust.
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article
The origin of GEMS in IDPs as deduced from microstructural evolution of amorphous silicates with annealing
Abstract
Aims.We present laboratory studies of the micro-structural evolution of an amorphous ferro-magnesian silicate, of olivine composition, following thermal annealing under vacuum.Methods.The amorphous silicate was prepared as a thin film on a diamond substrate. Annealing under vacuum was performed at temperatures ranging from 870 to 1020 K. After annealing the thin films were extracted from the substrate and analysed by transmission electron microscopy to infer their microstructural and compositional evolution.Results.Spheroidal metallic nano-particles (2-50 nm) are found within the silicate films, which are still amorphous after annealing at 870 K and partially crystallized into forsterite for annealing up to 1020 K. We interpret this microstructure in terms of a reduction of the initial amorphous silicate FeO component, because of the carbon-rich partial pressure in the furnace due to pumping mechanism. Annealing in a controlled oxygen-rich atmosphere confirms this interpretation. Conclusions.The observed microstructures closely resemble those of the GEMS (Glass with Embedded Metal and Sulphides) found in chondritic IDPs (Interplanetary Dust Particles). Since IDPs contain abundant carbonaceous matter, a solid-state reduction reaction may have occurred during heating in the hot inner regions of the proto-solar disc. Related to this, the presence of forsterite grains grown from the amorphous precursor material clearly demonstrates that condensation from gaseous species is not required to explain the occurrence of forsterite around young protostars and in comets. Forsterite grains in these environments can be formed directly in the solid phase by thermal annealing of amorphous ferro-magnesian silicates precursor under reducing conditions. Finally, locking iron as metallic particles within the silicates explains why astronomical silicates always appear observationally Mg-rich....