Effect of Temperature on AuPd Nanoparticles Produced by Inert Gas Condensation

Abstract

Bimetallic nanoparticles of AuPd were synthesized using the inert gas condensation technique, where the material is sputtered from a target and the particles are formed in an inert condensation zone. Throughout the synthesis process and jointly with the control of the atmosphere conditions, the region after the condensation chamber was kept at a fixed temperature, and several experimental runs were performed at 700 and 1000°C. The synthesis conditions were set to produce particles of 5 nm of diameter, and almost all of the resulting nanoparticles were icosahedral in shape with small deviations from the mean size. We analyzed the particles by high-angle annular dark field and bright field scanning electron microscopy imaging with a resolution high enough to acquire atomic detail and to measure the distance between planes. From the micrographs and their fast Fourier transform patterns, we found that the lattice detail depends on the thermal treatment with larger lattice fringe displacements in the particles produced at 700°C. Electron energy loss spectroscopy analysis in one and two dimensions shows that irrespective of the temperature the particles keep their icosahedral shape, and both chemical species are distributed nonuniformly all over the volume of the particles, but without forming core-shell structures.

Size and alloying induced changes in lattice constant, core, and valance band binding energy in Pd-Ag, Pd, and Ag nanoparticles: Effect of in-flight sintering temperature

“…In physical methods of Pd-alloy NP synthesis, sequential or coevaporation of the two components using e-beam, thermal heating, sputtering, and laser ablation has been employed for growing Pd alloy thin films, nanocrystalline, and nanoparticulate layers. [7][8][9][10] These techniques normally yield alloy thin films or nanoparticulate layers of undefined topography, having large variations in composition or metallic and alloy multiphases in the same sample. In chemical methods, electrochemical synthesis, chemical reduction, and thermal decomposition of Pd or Pd-alloy complexes are widely reported.…”

Metal/Metal-Oxide Nanoclusters for Gas Sensor Applications

“…A summary of those methods is presented in Figure 4. Although examples of the usage of nanoclusters synthesized using different methods for gas sensing applications will be presented in this review, special focus will be given to nanocluster synthesis using the inert gas condensation technique because of its many advantages as discussed below [42][43][44][45].…”

Molecular dynamics of coalescence and collisions of silver nanoparticles

“…The icosahedral shape was selected due to its common appearance on silver (and other metal) particles at this range of sizes (Perez-Tijerina et al 2010), and because with this choice, a small number of nonequivalent orientations can be used to form the set of starting configurations. Ten different orientations were considered in this study: (i) edge-to-edge, (ii) edge-to-face, (iii) edge-to-vertex, (iv) edge-to-random, (v)face-to-face, (vi) face-to-vertex, (vii) face-torandom, (viii) vertex-to-vertex , (ix) vertex-to-random, and (x) random-to-random.…”

“…Different velocities were tested for each orientation, ranging from 0 m/s (pure coalescence at contact) to 500 m/s; this range of velocities covers the typical conditions at which the particles collide in an inert gas condensation process (Perez-Tijerina et al 2010). It was found that in this range only the velocity of 500 m/s gave the particles the enough kinetic energy to deform the original nanoparticles to promote the creation of a new nanoparticle, with a well-defined center.…”