Fully Crystalline Faceted Fe–Au Core–Shell Nanoparticles

Abstract

Fe-Au core-shell nanoparticles displaying an original polyhedral morphology have been successfully synthesized through a physical route. Analyses using transmission electron microscopy show that the Au shell forms truncated pyramids epitaxially grown on the (100) facets of the iron cubic core. The evolution of the elastic energy and strain field in the nanoparticles as a function of their geometry and composition is calculated using the finite-element method. The stability of the remarkable centered core-shell morphology experimentally observed is attributed to the weak elastic energy resulting from the low misfit at the Fe/Au (100) interface compared to the surface energy contribution.

Effect of van der Waals corrections on DFT-computed metallic surface properties

“…Al(111), Cu(111), Au(111), Ni(111), Co(0001) and Fe(110). Five of the six metals studied are transition metals and all have been chosen because of their frequent use as molecular adsorption substrates or as stable facets of nanoparticles [28][29][30]. We tested one example for each of the two most representative classes of vdW correction methods (non-local correlation functional and semi-empirical additive DFT-D).…”

How the crystal structure and phase segregation of Au–Fe alloy nanoparticles are ruled by the molar fraction and size

“…This is surprising as in accordance with the Hume-Rothery rule, 15 miscibility of Au and Fe defines the system as mostly immiscible (bulk solubility at room temperature: 3% Au in Fe and 0.3% Au in Fe) 5 because of the differences in the lattice parameters (Au FCC 4.076 Å; Fe BCC 2.866 Å) and in the surface energies (Au 1.5 J m −2 ; Fe 2.4 J m −2 ). 16,17 Based on this, the segregated phase (CS) should be the only thermodynamically stable phase. To examine this phenomenon in more detail, we determined the crystal structure of the generated Au-Fe NPs by X-ray powder diffraction (XRD) including Rietveld refinement and the calculation of lattice parameters for FCC and BCC phases ( Fig.…”

Alloy, Janus and core–shell nanoparticles: numerical modeling of their nucleation and growth in physical synthesis

“…Most recent research efforts went into raising the complexity of the material and multicomponent systems are increasingly researched in order to combine several properties within the same NP [20][21][22]. For binary systems, three different types of morphology are observed (1) alloy [23][24][25][26], (2) core-shell [27][28][29][30][31][32] and (3) Janus [11,[33][34][35].…”

“…Owing to their simplicity and their ability to generate a wealth of structures, physical synthesis methods represent an appealing alternative to more traditional soft chemistry routes and should be crucial to reach an ondemand synthesis of nanomaterials in general [27,32,[36][37][38][39][40][41][42][43][44]. Physical synthesis methods include laser ablation [45][46][47][48], flame pyrolysis [49][50][51], or magnetron sputtering [45,52,53] and always start with the production of an initially hot gas.…”

“…These methods are highly versatile and easily controllable via experimental parameters. The out-of-equilibrium state during the growth process and the formation kinetics both play a crucial role in determining particle properties [54,55] and should therefore help obtaining new exotic structures and morphologies [27,32,38,39,43]. * julien.lam@ulb.ac.be However, due to their complexity, details of the NP formation processes are still not very well understood.…”