Dense Liquid Precursor in Mineral Crystallization: Spinodal Morphology and High Viscosity Evidenced by Electron Imaging.

Recent consensus suggests that the classical single-step nucleation theory, a key reference for nanomaterial synthesis, inadequately explains nanocrystal formation in solutions, as it ignores noncrystalline intermediate structures. Among these, reactant-rich liquid nanostructures have gained attention for their potential to differentiate between crystallization theories. However, capturing their physical properties at the nanometer scale before crystallization remains challenging.

Micro- and milli-fluidic sample environments for X-ray analysis in the chemical and materials sciences.

X-ray-based methods are powerful tools for structural and chemical studies of materials and processes, particularly for performing time-resolved measurements. In this critical review, we highlight progress in the development of X-ray compatible microfluidic and millifluidic platforms that enable high temporal and spatial resolution X-ray analysis across the chemical and materials sciences. With a focus on liquid samples and suspensions, we first present the origins of microfluidic sample environments for X-ray analysis by discussing some alternative liquid sample holder and manipulator technologies.

Superoxide Production under Soft X-ray Irradiation of Liquid Water.

Soft X-rays behave like particles with high linear energy transfer, as they deposit a large amount of their energy in the nanometric range, triggered by inner-shell ionization. In water, this can lead to the formation of a doubly ionized water molecule (HO) and the emission of two secondary electrons (photoelectron and Auger electron). Our focus lies on detecting and quantifying the superoxide (HO°) production via the direct pathway, i.

Coexistence of Transient Liquid Droplets and Amorphous Solid Particles in Nonclassical Crystallization of Cerium Oxalate.

Crystallization from solution often occurs via "nonclassical" routes; that is, it involves transient, non-crystalline states like reactant-rich liquid droplets and amorphous particles. However, in mineral crystals, the well-defined thermodynamic character of liquid droplets and whether they convert─or not─into amorphous phases have remained unassessed. Here, by combining cryo-transmission electron microscopy and X-ray scattering down to a 250 ms reaction time, we unveil that crystallization of cerium oxalate involves a metastable chemical equilibrium between transient liquid droplets and solid amorphous particles: contrary to the usual expectation, reactant-rich droplets do not evolve into amorphous solids.

Amorphous-to-crystal transition in the layer-by-layer growth of bivalve shell prisms.

Biomineralization integrates complex physical and chemical processes bio-controlled by the living organisms through ionic concentration regulation and organic molecules production. It allows tuning the structural, optical and mechanical properties of hard tissues during ambient-condition crystallisation, motivating a deeper understanding of the underlying processes. By combining state-of-the-art optical and X-ray microscopy methods, we investigated early-mineralized calcareous units from two bivalve species, Pinctada margaritifera and Pinna nobilis, revealing chemical and crystallographic structural insights.