Controlling the size distribution of embedded Au nanoparticles using ion irradiation

Abstract

Samples composted of chemically synthesized Au nanoparticles (NPs) (16.0±2.0 nm) embedded within a planar silica film are used as model system to investigate the evolution of a second phase under irradiation when the temperature and the ion stopping power are changed. Samples are irradiated with 4 MeV Au2+ ions and 4 MeV Br2+ ions for temperature ranging from 30 °C up to 800 °C and for fluences up to 8×1016 cm−2. We show that at room temperature the complete dissolution of the NPs leads to the formation of smaller precipitates with a narrower size distribution, i.e., 2.0±0.3 nm. However, when the temperature is increased and/or the nuclear stopping power is decreased, a reduction in the dissolution rate was observed. This leads to the formation of a bimodal size distribution. Finally, the evolution of the density of the precipitates with the temperature is discussed in term of the thermal stability of the irradiation-induced defects within the silica matrix.

Three-Dimensional Modeling of Embedded Nanoparticles Formation by Ion Beam Implantation

“…This was the well-known growth process of Ostwald ripening, and had been confirmed in many similar experimental observations of ion implantations. [30][31][32][33] For a condition of very high ion fluence, a buried layer of implanted atoms in the matrix would form by coalescence, as shown in Figure 2 These simulation results were fully consistent with many experimental observations, [30][31][32][33][34][35][36][37] and well explained the spatial and size distributions of implanted ions during ion implantation. For a condition of increasing ion mass, the distribution profile of implanted ions in the theoretical calculation was changed to the curve of Figure 1(b), while keeping all other simulation parameters the same as those in Figure 2.…”

On the evolution of the steady state in gold-silica nanocomposites under sustained irradiation

“…The crossover between these two regimes can be accounted for by considering the mobility of the defects within the host matrix. Indeed, the transition temperature is in agreement with the existing results indicating that irradiationinduced defects become mobile above 750-800 K. [33][34][35][36][37][38][39][40][41][42] The experimental data are fitted using the Dienes and Damask model. 37 The latter predicts the existence of two temperature regimes for the diffusion.…”

Nanoscale structuration and optical properties of thin gold films on textured FTO

“…Au nanoparticles (NPs) are obtained on the glass/FTO substrate by nanosecond laser irradiation of sputterdeposited Au films. Among bottom-up methods, used to obtain nanoscale metal structures [19][20][21][22][23][24][25][26][27][28], the application of ultrafast lasers for material nano-processing allows to obtain a wide variety of nanostructures as a result of laserinduced melting and solidification dynamics [29][30][31][32][33][34][35][36][37][38][39][40]. The main advantages of laser-based approaches include local processing down to the micrometer and sub-micrometer range; minimized thermal damage to the substrate and neighboring regions; non-contact nature; and non-planar processing.…”