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This paper describes the 3D printing of a ternary composite of polydimethylsiloxane (PDMS) and nanoparticles of iron oxide and barium titanate. The composite was printed using a commercially available 3D printer. Thermal curing of the composite during printing allowed for overall low process times of a few minutes. Scanning electron microscopy indicated uniform composite layers. The resulting composite films showed ferromagnetic behaviour, and applicability in magnetic actuation and piezoelectric energy harvesting. 

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 (<2.5 nm) had a truncated octahedral shape, bound by 〈111〉 and 〈100〉 facets, as predicted by lowest-energy thermodynamics. However, as particle size increased, the higher-energy 〈110〉 facets became increasingly common, leading to a large population of non-equilibrium truncated cuboctahedra. The observed trends were explained by combining atomistic simulations (both molecular dynamics and an empirical square-root bond-cutting model) with Boltzmann statistics. Overall, this study demonstrates experimentally how thermal energy leads to shape variation in populations of metal nanoparticles, and reveals the dependence of shape distributions on particle size. The prevalence of non-equilibrium facets has implications for metal nanoparticles applications from catalysis to solar energy. 

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.