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While combining two metals in the same nanoparticle can lead to remarkable novel applications, the resulting structure in terms of crystallinity and shape remains difficult to predict. It is thus essential to provide a detailed atomistic picture of the underlying growth processes. In the present work we address the case of core-shell Fe-Au and Fe-Ag nanoparticles. Interface properties between Fe and the noble metals Au and Ag, computed using DFT, were used to parameterize Fe-Au and Fe-Ag pairwise interactions in combination with available many-body potentials for the pure elements. The growth of Au or Ag shells on nanometric Fe cores with prescribed shapes was then modelled by means of Monte Carlo simulations. The shape of the obtained Fe-Au nanoparticles is found to strongly evolve with the amount of metal deposited on the Fe core, a transition from the polyhedral Wulff shape of bare iron to a cubic shape taking place as the amount of deposited gold exceeds two monolayers. In striking contrast, the growth of silver proceeds in a much more anisotropic, Janus-like way and with a lesser dependence on the iron core shape. In both cases, the predicted morphologies are found to be in good agreement with experimental observations in which the nanoparticles are grown by physical deposition methods. Understanding the origin of these differences, which can be traced back to subtle variations in the electronic structure of the Au/Fe and Ag/Fe interfaces, should further contribute to the better design of core-shell bimetallic nanoparticles., SCOPUS: ar.j, DecretOANoAutActif, info:eu-repo/semantics/published

In nanoscience, one always has to question how the basic theories we use at the macro- and meso- scales (continuum elasticity and plasticity, etc) apply at the nanometre scale. Studying mechanical properties of nano-size objects also challenges the experimental approaches: how to implement reproducible and controllable mechanical loading? How to measure fields (displacement, stress, strain, etc) with the required nano-resolution? Moreover nanoscience is often tackling the limits of continuum theories and thus simulation is an increasingly important tool to evaluate the different scale transitions needed from atoms to nano-objects. This book provides an updated view of the rapidly growing field of mechanical properties of nano-objects like micropillars, nanowires, nano-particles, nano-precipitates, nano-twins, MEMS, NEMS and structured surfaces, etc. It addresses the theoretical and experimental issues that span the field of mechanics at small dimensions: the fundamentals of continuum mechanics and the mechanics of defects, a general state-of-the-art about modelling and simulation and an overview of the size dependent mechanical properties of nano-objects. Fascinating recent advances are shown in the evaluation of displacement fields at the nano scale by X-ray diffraction and transmission electron microscopy. Examples are given of systems where mastering mechanical properties in small dimensions is key to control the final aimed property (electrical, optical, mechanical, etc).

In nanoscience, one always has to question how the basic theories we use at the macro- and meso- scales (continuum elasticity and plasticity, etc) apply at the nanometre scale. Studying mechanical properties of nano-size objects also challenges the experimental approaches: how to implement reproducible and controllable mechanical loading? How to measure fields (displacement, stress, strain, etc) with the required nano-resolution? Moreover nanoscience is often tackling the limits of continuum theories and thus simulation is an increasingly important tool to evaluate the different scale transitions needed from atoms to nano-objects. This book provides an updated view of the rapidly growing field of mechanical properties of nano-objects like micropillars, nanowires, nano-particles, nano-precipitates, nano-twins, MEMS, NEMS and structured surfaces, etc. It addresses the theoretical and experimental issues that span the field of mechanics at small dimensions: the fundamentals of continuum mechanics and the mechanics of defects, a general state-of-the-art about modelling and simulation and an overview of the size dependent mechanical properties of nano-objects. Fascinating recent advances are shown in the evaluation of displacement fields at the nano scale by X-ray diffraction and transmission electron microscopy. Examples are given of systems where mastering mechanical properties in small dimensions is key to control the final aimed property (electrical, optical, mechanical, etc).

In nanoscience, one always has to question how the basic theories we use at the macro- and meso- scales (continuum elasticity and plasticity, etc) apply at the nanometre scale. Studying mechanical properties of nano-size objects also challenges the experimental approaches: how to implement reproducible and controllable mechanical loading? How to measure fields (displacement, stress, strain, etc) with the required nano-resolution? Moreover nanoscience is often tackling the limits of continuum theories and thus simulation is an increasingly important tool to evaluate the different scale transitions needed from atoms to nano-objects. This book provides an updated view of the rapidly growing field of mechanical properties of nano-objects like micropillars, nanowires, nano-particles, nano-precipitates, nano-twins, MEMS, NEMS and structured surfaces, etc. It addresses the theoretical and experimental issues that span the field of mechanics at small dimensions: the fundamentals of continuum mechanics and the mechanics of defects, a general state-of-the-art about modelling and simulation and an overview of the size dependent mechanical properties of nano-objects. Fascinating recent advances are shown in the evaluation of displacement fields at the nano scale by X-ray diffraction and transmission electron microscopy. Examples are given of systems where mastering mechanical properties in small dimensions is key to control the final aimed property (electrical, optical, mechanical, etc).