Growth and lattice dynamics of Co nanoparticles embedded in Ag: A combined molecular-dynamics simulation and Mössbauer study

Abstract

We use Mössbauer spectroscopy in combination with atomic scale modeling in order to gather a comprehensive understanding of the growth and the dynamics of cobalt nanoprecipitates in silver. The modeling makes use of classical molecular dynamics in the canonical ensemble by means of the Rahman-Parinello technique. Atomic interactions are governed by an embedded atom model, which is validated for the static Co-Ag interaction by means of a comparison with extended x-ray absorption fine structure measurements and for the dynamical interaction with Mössbauer spectroscopy data. This allows us to identify the cluster size dependent atomic arrangements at the cluster-matrix interface, where strong relaxation takes place. A detailed analysis of the Mössbauer spectra taken at two temperatures after annealing at different temperatures allows us not only to characterize the cluster size dependence of magnetic properties, but also to evidence a possible Ostwald ripening growth mechanism. The mean and interface Debye temperatures are deduced from the Mössbauer spectra and found quite consistent with the model predictions. On this basis, the atomic scale modeling allows us to identify detail of atomic vibrational properties as a function of distance from the cluster center and a discontinuity of the vibration amplitudes at the precipitate-matrix interface is evidenced.PRB 62 5121 GROWTH AND LATTICE DYNAMICS OF Co . . .

Size‐, dimensionality‐, and composition‐dependent Debye temperature of monometallic and bimetallic nanocrystals in the deep nanometer scale

“…From Fig. 3, it can be seen that the size effects on Q D (x, r, d) of Zr 90 Al 10 and Zr 84 Al 16 nanoparticles are different. This is ascribed to the strong composition effect in bimetallic nanocrystals, in particular for the mixture of alloy components with distinct lattice constants.…”

Size Dependent Debye Temperature and Total Mean Square Relative Atomic Displacement in Nanosolids under High Pressure and High Temperature

“…It is interesting to note that the surface mode contribution of nanoclusters can largely influence the MSRD. Also, Hou and co-workers 10 revealed that the strong relaxation takes place at the Co cluster-Ag matrix interface due to cluster size dependent atomic arrangements. The atomic vibrational properties at the interface depend functionally on cluster size and a discontinuity of the amplitudes at the Co/Ag interface.…”

“…However, little has been known insofar from the perspective of the atomistic origin about the quantitative MSRD in nanosolids under the conditions of coupling effects of high pressure and high temperature. 10,13 In this paper, we developed a solid size, pressure, and temperature dependence of Debye temperature to elucidate the total MSRD of a nanosolid. Importantly, the theoretical predictions made on the basis of the proposed model are in agreement with the experimental measurements and simulations results.…”

Size dependence of phase transition temperatures of ferromagnetic, ferroelectric and superconductive nanocrystals

“…(13) with d = 0, 1 and 2 for the nanoparticles, the nanowires or nanorods and the thin films, respectively, while the computer simulation results are done with d = 0 [117,122]. The ∞ ∞ ∞ granular films cannot be described as a continuous film [108,118] since they are of high densities of inner surfaces or grain boundaries.…”