Metallic iron limits silicate hydration in Earth’s transition zone

Chemistry of Silicate Atmospheres of Evaporating Super- Earths

Iron isotopic fractionation between silicate mantle and metallic core at high pressure

The +0.1‰ elevated 56Fe/54Fe ratio of terrestrial basalts relative to chondrites was proposed to be a fingerprint of core-mantle segregation. However, the extent of iron isotopic fractionation between molten metal and silicate under high pressure-temperature conditions is poorly known. Here we show that iron forms chemical bonds of similar strengths in basaltic glasses and iron-rich alloys, eve...

Detecting biomarkers in habitable-zone earths transiting white dwarfs

The characterization of the atmospheres of habitable-zone Earth-mass exoplanets that transit across main-sequence stars, let alone the detection of biomarkers in their atmospheres, will be challenging even with future facilities. It has been noted that white dwarfs (WDs) have long-lived habitable zones and that a large fraction of WDs may host planets. We point out that during a transit of an E...

Hydration of tricalcium silicate in the presence of synthetic calcium–silicate–hydrate

The early age-hydration of tricalcium silicate, the main chemical compound in Portland cement, was studied in the presence of synthetic calcium silicate hydrate (C–S–H) addition having C/S ratios 1⁄4 0.8 and 1.2. Isothermal conduction calorimetry, scanning electron microscopy, differential scanning calorimetry and Si MAS NMR were employed in order to investigate events occurring during various ...

Hydration water and microstructure in calcium silicate and aluminate hydrates

Understanding the state of the hydration water and the microstructure development in a cement paste is likely to be the key for the improvement of its ultimate strength and durability. In order to distinguish and characterize the reacted and unreacted water, the single-particle dynamics of water molecules in hydrated calcium silicates (C3S, C2S) and aluminates (C3A, C4AF) were studied by quasi-...