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While it is well established that nanoparticle shape can depend on equilibrium thermodynamics or growth kinetics, recent computational work has suggested the importance of thermal energy in controlling the distribution of shapes in populations of nanoparticles. Here, we used transmission electron microscopy to characterize the shapes of bare platinum nanoparticles and observed a strong dependence of shape distribution on particle size. Specifically, the smallest nanoparticles (

Recent increasing uses of ceria in research and industrial applications have fostered continuing developments of efficient routes to synthesize the material. Here we report our investigation of the effects and the mechanistic roles of lithium acetate to accelerate the growth of crystalline ceria nanoparticles in ozone-mediated synthesis. By increasing the mole ratio of the acetate to cerium nitrate in the reactions, the reaction yields of ceria nanoparticles were observed to increase from ca. 10% to up to over 90% by cerium content in 30 min reactions. Microscopy images and Raman spectra of the as-synthesized nanoparticles revealed that increasing the acetate additions led to a decrease in average particle size and size range but an increase in crystallinity. Through analyzing the organic by-products in the reaction mixtures, the acetate was inferred to base-catalyze the formation of acetals and cerium complexes and accelerate the formation of Ce–O–Ce bonds and hence the growth of ceria nanoparticles through alcohol-like condensation reactions.

Owing to their low density and high strength-to-weight ratio, Mg alloys are attractive for automotive and aerospace applications. However, the current use of magnesium in the industry is limited due to the low strength and poor formability at ambient temperatures. Two-phase nanostructured materials are a promising solution to improve the mechanical properties of Mg alloys. Depending on processing parameters, either fibrous or lamellar morphologies can be formed via the eutectic transformation. In this work, the mechanical behavior of these two different morphologies were examined by in-situ SEM microcompression tests. The lamellar morphology exhibited a superior combination of strength and plasticity with respect to the fibrous morphology, and both showed superior strength relative to pure Mg, up to five-fold in the former and 12-fold in the latter. However, the higher strength in the fibrous eutectic was obtained at the expense of a low plasticity. According to the HR/TEM analyses of the deformed micropillars, the relatively high plasticity of the lamellar morphology was attributed to the two reasons; on the one hand, high dislocation activity was observed in both α and β phases and resulted in plastic co-deformation of the layers. On the other hand, the α layers played a significant role in restricting the shear instabilities that initiated in the β layers. Such an effect was not observed with the fibrous morphologies, and thus, they failed by cleavage along the closest-packed planes in the β crystal.