...Liberto De Pablo Galan; Mercedes Doval; Angel La Iglesia; Jesus Soriano; Lourdes Chavez Abstract Cristobalite-tridymite blade nanocrystals cemented by SiO 2 -glass and tridymite nanocrystals fill separately SiO 2 -glass spherules released by explosive volcanism, in rhyolitic tuffs from the Province...

... and the formation of new continental crust between 2.51 to 2.45 Ga. Here we report unique mineral evidence for momentary subaerial volcanism recorded in hematite-rich layers of the 2.48 Ga BIF from Dales Gorge, Hamersley of Western Australia. The BIF contains euhedral quartz nanocrystals (QNC), which only occur...

... of the nanocrystals and SAED patterns simulated using the structure of vorlanite ( Figs. 3a , 3b , and 3c ). Figure 3d shows the cubic oxygen coordination of U 6+ in this mineral. All vorlanite nanocrystals observed correspond to euhedral cubes, 20 to 150 nm large ( Fig. 2a and inset in Fig. 3a ). After...

...Takuya Echigo; Niven Monsegue; Deborah M. Aruguete; Mitsuhiro Murayama; Michael F. Hochella, Jr. Abstract We report the first characterization of the internal structural features within rhombohedral nanocrystals of hematite (α-Fe 2 O 3 ), specifically nanoscale pores (nanopores) within...

...}\ {-}\ \mathit{C}_{\mathit{A}})\ \frac{k_{B}\mathit{T}}{\mathit{h}}\ exp\left(\frac{{-}{\Delta}\mathit{g}_{\mathit{D}}^{0}}{k_{B}\mathit{T}}\right)\] \end{document} where Δ g D 0 is the standard free energy of activation of a diffusion step. As our model is meant to be applied to nanocrystals, we...

...Mihály Pósfai; Rafal E. Dunin-Borkowski Abstract Ferrimagnetic nanocrystals are present in virtually every organism. they are used by bacteria, algae, mollusks, insects, and vertebrates either for navigating in the geomagnetic field or for hardening their tissues. advanced transmission electron...

... of up to four sets of oriented rod-shaped CaO nanocrystals on each rhombohedral cleavage face of the calcite pseudomorph. The four sets formed on (101̅4) calcite display the following topotactic relationships: (1) (12̅10) calcite //(110) CaO ; (2) (1̅104) calcite ⊥ (110) CaO ; (3) (1̅018) calcite //(110...

...Erica Bittarello; Dino Aquilano Abstract “Silica Biomorphs” are self-assembled nanocrystals of barium carbonate that form in silica-rich environments. Their morphologies are highly reminiscent of the shapes of primitive life (discovered in Archean cherts), but the precipitates are clearly inorganic...

.... Chemical analyses show dominant Fe 2 O 3 (53.5–71.5 wt.%), with minor SiO 2 (3.0–24.7 wt.%) and Al 2 O 3 (0.8–7.1 wt.%). A very high arsenic content characterizes all the samples (with a mean of 5.6 wt.% As 2 O 5 ). Goethite and hematite occur as finely dispersed nanocrystals, respectively 2–10 nm and 10...

..., as well as on the contribution of biogenic greigite to the paleomagnetic signal in sedimentary deposits. Off-axis electron holography is a transmission electron microscopy (TEM) technique that can be used to study the magnetic microstructures of nanocrystals ( Dunin-Borkowski et al. 2004 ). The method...

... of the kinetics, which depends strongly on the preparation of the sample and its history. The study of first-order phase transitions can be greatly simplified in nanocrystal systems because small crystals can behave as single structural domains and reproducibly cycle through multiple transitions ( Wickham et al...

... sizes of single crystallites in the 1 — 50 nm range and agglomerate grain sizes up to 4 μm. The three-dimensional agglomerates are built with different biomineral nanocrystals in three distinct modes of biological self-assembly: 1) ordered magnetite; 2) semi-ordered mixture of magnetite and ϵFe 2 O 3...