The Experts below are selected from a list of 7242 Experts worldwide ranked by ideXlab platform
T. Di Iorio - One of the best experts on this subject based on the ideXlab platform.
-
vis ir study of Brucite clay carbonate mixtures implications for ceres surface composition
Icarus, 2016Co-Authors: S. De Angelis, P. Manzari, M. C. De Sanctis, Eleonora Ammannito, T. Di IorioAbstract:Abstract Carbonates and clay minerals are present in Solar System bodies such as Mars and asteroid (1) Ceres. Brucite has been proposed in the recent past to fit absorption features in spectra of Ceres. In this study Visible-Near Infrared reflectance spectroscopic measurements have been performed on Brucite–carbonate–clay minerals mixtures, in the 0.2–5.1 µm spectral range. Different sets of three- and two-components mixtures have been prepared using these three fine powdered endmembers, by varying the relative proportions of carbonate, clay and Brucite. Spectra have been acquired on the endmembers components separately and on the mixtures. Absorption features diagnostic of the carbonate, clay and Brucite phases have been analyzed and band parameters (position, depth, area, width) determined. Several trends and correlations with mineral phase content in each mixture have been investigated, with the aim to determining how endmember components influence the mixture spectra and their minimum detectability threshold. Our results indicate that Brucite is detectable in mineral mixtures with carbonates and clays, based on its main absorption features at 0.95, 2.45–2.47 and 3.05 µm. While the 0.95 and 3.05 µm features are only discernible for very high Brucite contents in the mixtures, the ∼2.45 µm band turns out to be highly diagnostic, also for very small amounts of Brucite (of the order of 10 wt%). These experiments, together with DAWN observations of Ceres, substantially rule out the presence of great amounts of Brucite globally distributed on the surface of Ceres.
-
VIS-IR study of Brucite–clay–carbonate mixtures: Implications for Ceres surface composition
Icarus, 2016Co-Authors: S. De Angelis, P. Manzari, M. C. De Sanctis, Eleonora Ammannito, T. Di IorioAbstract:Abstract Carbonates and clay minerals are present in Solar System bodies such as Mars and asteroid (1) Ceres. Brucite has been proposed in the recent past to fit absorption features in spectra of Ceres. In this study Visible-Near Infrared reflectance spectroscopic measurements have been performed on Brucite–carbonate–clay minerals mixtures, in the 0.2–5.1 µm spectral range. Different sets of three- and two-components mixtures have been prepared using these three fine powdered endmembers, by varying the relative proportions of carbonate, clay and Brucite. Spectra have been acquired on the endmembers components separately and on the mixtures. Absorption features diagnostic of the carbonate, clay and Brucite phases have been analyzed and band parameters (position, depth, area, width) determined. Several trends and correlations with mineral phase content in each mixture have been investigated, with the aim to determining how endmember components influence the mixture spectra and their minimum detectability threshold. Our results indicate that Brucite is detectable in mineral mixtures with carbonates and clays, based on its main absorption features at 0.95, 2.45–2.47 and 3.05 µm. While the 0.95 and 3.05 µm features are only discernible for very high Brucite contents in the mixtures, the ∼2.45 µm band turns out to be highly diagnostic, also for very small amounts of Brucite (of the order of 10 wt%). These experiments, together with DAWN observations of Ceres, substantially rule out the presence of great amounts of Brucite globally distributed on the surface of Ceres.
Tingting Zhang - One of the best experts on this subject based on the ideXlab platform.
-
formation of magnesium silicate hydrate m s h cement pastes using sodium hexametaphosphate
Cement and Concrete Research, 2014Co-Authors: Luc J. Vandeperre, Tingting Zhang, Christopher R. CheesemanAbstract:Magnesium silicate hydrate (M-S-H) gel is formed by the reaction of Brucite with amorphous silica during sulphate attack in concrete and M-S-H is therefore regarded as having limited cementing properties. The aim of this work was to form M-S-H pastes, characterise the hydration reactions and assess the resulting properties. It is shown that M-S-H pastes can be prepared by reacting magnesium oxide (MgO) and silica fume (SF) at low water to solid ratio using sodium hexametaphosphate (NaHMP) as a dispersant. Characterisation of the hydration reactions by x-ray diffraction and thermogravimetric analysis shows that Brucite and M-S-H gel are formed and that for samples containing 60 wt.% SF and 40 wt.% MgO all of the Brucites react with SF to form M-S-H gel. These M-S-H cement pastes were found to have compressive strengths in excess of 70 MPa.
-
development of low ph cement systems forming magnesium silicate hydrate m s h
Cement and Concrete Research, 2011Co-Authors: Tingting Zhang, Christopher R. Cheeseman, Luc J. VandeperreAbstract:This work aimed to develop novel cement systems for waste encapsulation that would form with a pH of around 10. The approach taken was to investigate the formation of Brucite by hydration of a light burned periclase (MgO). Commercially available MgO powders often contain some CaO, and therefore silica fume was added to form C-S-H gel. Identification of the hydrated phases in MgO/silica fume samples showed that Brucite formed in substantial quantities as expected. However, Brucite reacted with the silica fume to produce a magnesium silicate hydrate (M-S-H) gel phase. After 28 days, the pH of systems rich in MgO tended towards the pH controlled by residual Brucite (~ 10.5), whereas when all Brucite reacts with silica fume a cement with an equilibrium pH just below 10 was achieved.
Clark M Johnson - One of the best experts on this subject based on the ideXlab platform.
-
magnesium isotope fractionation between Brucite mg oh 2 and mg aqueous species implications for silicate weathering and biogeochemical processes
Earth and Planetary Science Letters, 2014Co-Authors: Weiqiang Li, Brian L Beard, Chengxiang Li, Clark M JohnsonAbstract:Article history: Brucite, with its octahedral structure, has a lattice configuration that is similar to the Mg-bearing octahedral layers in phyllosilicates. Understanding stable Mg isotope fractionation between Brucite and aqueous solution therefore bears on interpretation of Mg isotope data in natural weathering systems. In this study, we experimentally determined Mg isotope fractionation between Brucite and two Mg aqueous species, the free Mg aquo ion ((Mg(OH2)6) 2+ ) and EDTA-bonded Mg (Mg-EDTA 2− ). Results from recrystallization and Brucite synthesis experiments suggest mild preferential partitioning of light Mg isotopes into Brucite compared to Mg aquo ions at low temperatures, where measured � 26 Mg Brucite-Mg 2+
Eleonora Ammannito - One of the best experts on this subject based on the ideXlab platform.
-
vis ir study of Brucite clay carbonate mixtures implications for ceres surface composition
Icarus, 2016Co-Authors: S. De Angelis, P. Manzari, M. C. De Sanctis, Eleonora Ammannito, T. Di IorioAbstract:Abstract Carbonates and clay minerals are present in Solar System bodies such as Mars and asteroid (1) Ceres. Brucite has been proposed in the recent past to fit absorption features in spectra of Ceres. In this study Visible-Near Infrared reflectance spectroscopic measurements have been performed on Brucite–carbonate–clay minerals mixtures, in the 0.2–5.1 µm spectral range. Different sets of three- and two-components mixtures have been prepared using these three fine powdered endmembers, by varying the relative proportions of carbonate, clay and Brucite. Spectra have been acquired on the endmembers components separately and on the mixtures. Absorption features diagnostic of the carbonate, clay and Brucite phases have been analyzed and band parameters (position, depth, area, width) determined. Several trends and correlations with mineral phase content in each mixture have been investigated, with the aim to determining how endmember components influence the mixture spectra and their minimum detectability threshold. Our results indicate that Brucite is detectable in mineral mixtures with carbonates and clays, based on its main absorption features at 0.95, 2.45–2.47 and 3.05 µm. While the 0.95 and 3.05 µm features are only discernible for very high Brucite contents in the mixtures, the ∼2.45 µm band turns out to be highly diagnostic, also for very small amounts of Brucite (of the order of 10 wt%). These experiments, together with DAWN observations of Ceres, substantially rule out the presence of great amounts of Brucite globally distributed on the surface of Ceres.
-
VIS-IR study of Brucite–clay–carbonate mixtures: Implications for Ceres surface composition
Icarus, 2016Co-Authors: S. De Angelis, P. Manzari, M. C. De Sanctis, Eleonora Ammannito, T. Di IorioAbstract:Abstract Carbonates and clay minerals are present in Solar System bodies such as Mars and asteroid (1) Ceres. Brucite has been proposed in the recent past to fit absorption features in spectra of Ceres. In this study Visible-Near Infrared reflectance spectroscopic measurements have been performed on Brucite–carbonate–clay minerals mixtures, in the 0.2–5.1 µm spectral range. Different sets of three- and two-components mixtures have been prepared using these three fine powdered endmembers, by varying the relative proportions of carbonate, clay and Brucite. Spectra have been acquired on the endmembers components separately and on the mixtures. Absorption features diagnostic of the carbonate, clay and Brucite phases have been analyzed and band parameters (position, depth, area, width) determined. Several trends and correlations with mineral phase content in each mixture have been investigated, with the aim to determining how endmember components influence the mixture spectra and their minimum detectability threshold. Our results indicate that Brucite is detectable in mineral mixtures with carbonates and clays, based on its main absorption features at 0.95, 2.45–2.47 and 3.05 µm. While the 0.95 and 3.05 µm features are only discernible for very high Brucite contents in the mixtures, the ∼2.45 µm band turns out to be highly diagnostic, also for very small amounts of Brucite (of the order of 10 wt%). These experiments, together with DAWN observations of Ceres, substantially rule out the presence of great amounts of Brucite globally distributed on the surface of Ceres.
S. De Angelis - One of the best experts on this subject based on the ideXlab platform.
-
vis ir study of Brucite clay carbonate mixtures implications for ceres surface composition
Icarus, 2016Co-Authors: S. De Angelis, P. Manzari, M. C. De Sanctis, Eleonora Ammannito, T. Di IorioAbstract:Abstract Carbonates and clay minerals are present in Solar System bodies such as Mars and asteroid (1) Ceres. Brucite has been proposed in the recent past to fit absorption features in spectra of Ceres. In this study Visible-Near Infrared reflectance spectroscopic measurements have been performed on Brucite–carbonate–clay minerals mixtures, in the 0.2–5.1 µm spectral range. Different sets of three- and two-components mixtures have been prepared using these three fine powdered endmembers, by varying the relative proportions of carbonate, clay and Brucite. Spectra have been acquired on the endmembers components separately and on the mixtures. Absorption features diagnostic of the carbonate, clay and Brucite phases have been analyzed and band parameters (position, depth, area, width) determined. Several trends and correlations with mineral phase content in each mixture have been investigated, with the aim to determining how endmember components influence the mixture spectra and their minimum detectability threshold. Our results indicate that Brucite is detectable in mineral mixtures with carbonates and clays, based on its main absorption features at 0.95, 2.45–2.47 and 3.05 µm. While the 0.95 and 3.05 µm features are only discernible for very high Brucite contents in the mixtures, the ∼2.45 µm band turns out to be highly diagnostic, also for very small amounts of Brucite (of the order of 10 wt%). These experiments, together with DAWN observations of Ceres, substantially rule out the presence of great amounts of Brucite globally distributed on the surface of Ceres.
-
VIS-IR study of Brucite–clay–carbonate mixtures: Implications for Ceres surface composition
Icarus, 2016Co-Authors: S. De Angelis, P. Manzari, M. C. De Sanctis, Eleonora Ammannito, T. Di IorioAbstract:Abstract Carbonates and clay minerals are present in Solar System bodies such as Mars and asteroid (1) Ceres. Brucite has been proposed in the recent past to fit absorption features in spectra of Ceres. In this study Visible-Near Infrared reflectance spectroscopic measurements have been performed on Brucite–carbonate–clay minerals mixtures, in the 0.2–5.1 µm spectral range. Different sets of three- and two-components mixtures have been prepared using these three fine powdered endmembers, by varying the relative proportions of carbonate, clay and Brucite. Spectra have been acquired on the endmembers components separately and on the mixtures. Absorption features diagnostic of the carbonate, clay and Brucite phases have been analyzed and band parameters (position, depth, area, width) determined. Several trends and correlations with mineral phase content in each mixture have been investigated, with the aim to determining how endmember components influence the mixture spectra and their minimum detectability threshold. Our results indicate that Brucite is detectable in mineral mixtures with carbonates and clays, based on its main absorption features at 0.95, 2.45–2.47 and 3.05 µm. While the 0.95 and 3.05 µm features are only discernible for very high Brucite contents in the mixtures, the ∼2.45 µm band turns out to be highly diagnostic, also for very small amounts of Brucite (of the order of 10 wt%). These experiments, together with DAWN observations of Ceres, substantially rule out the presence of great amounts of Brucite globally distributed on the surface of Ceres.
