We report on a real-time in situ TEM study of the coalescence of individual pairs of decahedral gold nanoparticles, which have been synthesized in solution. We observe the rate of growth of the neck that joins two particles during coalescence and compare this to classical continuum theory and to atomistic kinetic Monte Carlo simulations. We find good agreement between the observations and the simulations but not with the classical continuum model. This disagreement is attributed to the faceted nature of the particles.

Tungsten trioxide adopts a variety of structures which can be intercalated with charged species to alter the electronic properties, thus forming 'tungsten bronzes'. Similar optical effects are observed upon removing oxygen from WO3, although the electronic properties are slightly different. Here we present a computational study of cubic and hexagonal alkali bronzes and examine the effects on cell size and band structure as the size of the intercalated ion is increased. With the exception of hydrogen (which is predicted to be unstable as an intercalate), the behaviour of the bronzes are relatively consistent. NaWO3 is the most stable of the cubic systems, although in the hexagonal system the larger ions are more stable. The band structures are identical, with the intercalated atom donating its single electron to the tungsten 5d valence band. Next, this was extended to a study of fractional doping in the NaxWO3 system (0 ≤ x ≤ 1). A linear variation in cell parameter, and a systematic change in the position of the Fermi level up into the valence band was observed with increasing x. In the underdoped WO3−x system however, the Fermi level undergoes a sudden jump into the conduction band at around x = 0.2. Lastly, three compounds of a layered WO4 · α,ω-diaminoalkane hybrid series were studied and found to be insulating, with features in the band structure similar to those of the parent WO3 compound which relate well to experimental UVvisible spectroscopy results.

In situ synchrotron x-ray diffraction experiments on bare palladium nanoclusters prepared by inert-gas aggregation and size selected ͑1.7-6.0 nm͒ show significant changes in lattice parameter upon hydrogen loading and a narrowing of the miscibility gap, as the cluster size decreases. The results show that the miscibility gap is open for all cluster sizes studied, in contrast to previous literature results from surfactantencapsulated palladium clusters. We interpret these results by showing that the nature of the surface is critical in the hydrogenation behavior of the nanoclusters.