Quantification of initial steps of nucleation and growth of silica nanoparticles: An in-situ SAXS and DLS study

Amorphous dysprosium carbonate: characterization, stability, and crystallization pathways

“…Most of the research on such amorphous precursors has been focused on their compositional-dependent stabilities and on their formation and transformation conditions (i.e., amorphous calcium carbonates (Radha et al 2010;Goodwin et al 2010;Bolze et al 2002;Rodriguez-Blanco et al 2008) and amorphous calcium phosphates (Zyman et al 2010;Combes and Rey 2010). However, there are also salt systems where such amorphous precursors do either not crystallize even after very long time periods (Roncal-Herrero et al 2009;Tobler et al 2009) or where the formation of the thermodynamically stable end phase does not require an amorphous precursor as an initiators for the crystallization process (e.g., calcium sulfate, Van Driessche et al 2012;La and Nd-phosphates, Roncal-Herrero et al 2011). For example, amorphous silica when precipitated from solution (Tobler et al 2009;Tobler and Benning 2011) is stable for extremely long times without crystallizing, while in the La and Nd-phosphate system ) no amorphous precursor has so far been observed.…”

“…However, there are also salt systems where such amorphous precursors do either not crystallize even after very long time periods (Roncal-Herrero et al 2009;Tobler et al 2009) or where the formation of the thermodynamically stable end phase does not require an amorphous precursor as an initiators for the crystallization process (e.g., calcium sulfate, Van Driessche et al 2012;La and Nd-phosphates, Roncal-Herrero et al 2011). For example, amorphous silica when precipitated from solution (Tobler et al 2009;Tobler and Benning 2011) is stable for extremely long times without crystallizing, while in the La and Nd-phosphate system ) no amorphous precursor has so far been observed. However, in some salt systems, the formation of an amorphous precursor may at times be missed because the crystallization rates may be very rapid, as shown for the calcium carbonate systems (Bolze et al 2002;Bots et al 2012).…”

Analytical Transmission Electron Microscopy

“…More recent developments are taken from biological specimen preparation where thin layers of particle suspensions are rapidly frozen in solution allowing the hydrodynamic state of the particles and agglomerates to be observed (Hondow et al 2012). These cryo-quenching approaches and subsequent TEM imaging and analyses recently helped quantify in a time resolved manner the kinetics and mechanisms of several geological relevant reactions (e.g., Tobler et al 2009;Van Driessche et al 2012). In the geosciences, recent developments include the use of TEM imaging to track and quantify the kinetics of nanoparticle formation and transformation.…”

“…In the geosciences, recent developments include the use of TEM imaging to track and quantify the kinetics of nanoparticle formation and transformation. For example, conventional and cryo-TEM imaging helped quantify the nucleation and growth of amorphous silica (Tobler et al 2009). Similarly, using TEM imaging, SAED and associated pair distribution quantifications, the formation and aging of nanocrystalline iron sulfide phases (amorphous FeS, machinawite, greigite and pyrite; Csákberényi-Malasics et al 2012), which control the biogeochemical cycling of iron and sulfur in anoxic and suboxic marine sediments has been quantified.…”

Quantification Method of Size Distribution of Polysilicic Acid in Supersaturated Silicic Acid Solution

“…If a new method to estimate the absolute size distribution of polysilicic acid from the previous GPCm is developed, the polymerization of silicic acid in many geothermal waters may be clarified in detail. Recently, Dynamic Light Scattering (DLS), which can determine the hydrodynamic size of particles, has been applied to the investigation of the polymerization of silicic acid in geothermal water 8 with a relatively high concentration of silicic acid (1600 -2000 ppm as SiO2). A strong point of GPC is sensitivity for low silicic acid concentrations, but the absolute size distribution of polysilicic acid cannot be determined in principle.…”