We present a bottom-up fabrication route based on the sputtering gas aggregation source that allows the generation of nanoparticles with controllable and tunable chemical composition while keeping the control of the cluster size. We demonstrate that the chemical composition of the particles can be monitored by the individual adjustment of the working parameters of the magnetrons inserted in a gas aggregation zone. Such control of the parameters leads to a fine control of the ion density of each target material and hence to the control of the chemical composition of the nanoparticles. In particular, we show through X-ray photoemission, atomic force microscopy, and high-resolution transmission electron microscopy that it is possible to generate bimetallic (AgAu) and trimetallic (AgAuPd) alloy nanoparticles with well-defined and tunable stoichiometries from three targets of pure Ag, Au, and Pd. The proposed route for the generation of nanoparticles opens new possibilities for the fabrication of nanoparticles using a physical method that, for some applications, could be complementary to the chemical methods.
Complex core@shell and core@shell@shell nanoparticles are systems that combine the functionalities of the inner core and outer shell materials together with new physico-chemical properties originated by their low (nano) dimensionality. Such nanoparticles are of prime importance in the fast growing field of nanotechnology as building blocks for more sophisticated systems and a plethora of applications. Here, it is shown that although conceptually simple a modified gas aggregation approach allows the one-step generation of well-controlled complex nanoparticles. In particular, it is demonstrated that the atoms of the core and the shell of the nanoparticles can be easily inverted, avoiding intrinsic constraints of chemical methods.
Multiple Ion Cluster Source (MICS) is the new optimized route of a standard technique based on a sputtering gas aggregation source, the Ion Cluster Source. The single magnetron used in the standard Ion Cluster Source is replaced by three magnetrons inside the aggregation zone, and they are controlled individually in order to fabricate nanoparticles with the desired and tunable chemical composition. Apart from the working parameters of each magnetron, it is also reported that the relation between the working parameters of individual magnetrons is of prime importance for the control of both the size and density of the nanoparticles. The influences of fluxes of the sputtering gas applied to each magnetron, the total gas flux in the aggregation zone, the position in the aggregation zone of Ag magnetron, and the relative position of the magnetrons in the aggregation zone have been studied through the operation of one of the magnetrons loaded with a silver target.
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