Formation of calcium sulfate through the aggregation of sub-3 nanometre primary species
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2016Author:
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Stawski, T.M., van Driessche, A.E. S., Ossorio, M., Rodriguez-Blanco, J.D., Besselink, R., Benning, L.G., Formation of calcium sulfate through the aggregation of sub-3 nanometre primary species, Nature Communications, 2016, 7, 10177Download Item:
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Abstract:
The formation pathways of gypsum remain uncertain. Here, using truly in situ and fast time-resolved small-angle X-ray scattering, we quantify the four-stage solution-based nucleation and growth of gypsum (CaSO4·2H2O), an important mineral phase on Earth and Mars. The reaction starts through the fast formation of well-defined, primary species of <3 nm in length (stage I), followed in stage II by their arrangement into domains. The variations in volume fractions and electron densities suggest that these fast forming primary species contain Ca–SO4-cores that self-assemble in stage III into large aggregates. Within the aggregates these well-defined primary species start to grow (stage IV), and fully crystalize into gypsum through a structural rearrangement. Our results allow for a quantitative understanding of how natural calcium sulfate deposits may form on Earth and how a terrestrially unstable phase-like bassanite can persist at low-water activities currently dominating the surface of Mars.
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http://people.tcd.ie/rodrigjdDescription:
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Author: Rodriguez-Blanco, Juan
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Nature Communications;7;
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Gypsum, Natural calcium sulfate, MarsSubject (TCD):
Nanoscience & Materials , Smart & Sustainable PlanetLicences: