Composite Ni@Ti nanoparticles produced in arrow-shaped gas aggregation source

Abstract

A modified version of Haberland type gas aggregation source with an arrow-shaped aggregation chamber set with two magnetrons was used for the production of core@shell Ni@Ti nanoparticles. This configuration that had two separate magnetrons in one aggregation chamber gave the possibility to independently control the power to each magnetron and thus to control the structure of created nanoparticles. Furthermore, the chosen geometry resulted, under optimized conditions, in the suppression of the formation of single-material nanoparticles that is a common problem in the case of conventionally used planar arrangement of magnetrons in the aggregation chamber.

Continuous gas-phase synthesis of core–shell nanoparticles via surface segregation

“…Typically, the composition of gas phase synthesized nanoparticles is investigated by interrogating a large number of particles simultaneously. 25,26,71,72 This approach provides a good sample of ensemble-averaged properties of many particles, but cannot provide information on compositional variance between particles. Indeed, to the best of our knowledge, the compositional uniformity between individual bimetallic nanoparticles synthesized from coagulating and/or coalescing monometallic particles in the gas-phase is not well-documented.…”

“…Recently, gas-phase synthesis techniques based on low-pressure multi-magnetron gas aggregation sourceswhere one target acts as the source of the core material and the others as one or more sources coating materialshave enabled the fabrication of core-shell particles with tunable sizes and shapes. 23,24 Apart from the demanding high vacuum requirements, 25 these methods oen suffer from nucleation of pure-element byproducts, [24][25][26] and achieving uniformity in bimetallic morphology is challenging as the nanoparticles generated by non-equilibrium, fast kinetics processes that do not include an additional annealing process oen include random and unpredictable metastable phases. 27,28 Having control over size, composition, and morphology is desirable, as it enables investigations of the nanoparticle properties' effects on various applications.…”

Hybrid approaches coupling sol–gel and plasma for the deposition of oxide-based nanocomposite thin films: a review

“…More recently, gas aggregation nanocluster sources (GAS) have been used for the preparation of metal [76][77][78][79][80][81][82] or metal oxide nanoparticles such as TiO 2 ones [83][84][85][86], mainly based on vacuum metal evaporation or magnetron sputtering. This takes place in an aggregation chamber enclosed by an orifice through which the expanding gas (usually an inert gas such as Ar or N 2 ) carries the clusters into the low-pressure deposition chamber (typically ultrahigh vacuum one) [87].…”

Enhancing composition control of alloy nanoparticles from gas aggregation source by in operando optical emission spectroscopy

“…[ 39 ] In such a GAS, the NP sizes and size distributions are controlled by the magnetron power, gas flow, pressure, and aggregation length. [ 40 ] To produce alloy NPs inside such a GAS, three different ways are possible: the multiple magnetron approach, [ 40–44 ] the single‐alloy target approach, [ 45–47 ] and the multicomponent target approach. [ 48 ]…”

“…Recent approaches with multiple magnetrons in a single GAS apparatus have enabled good control over NP composition, but this approach is costly, needs huge source dimensions, and is experimentally challenging, because interferences between individual magnetrons make the plasma control sometimes difficult. [ 40–44 ] Nevertheless, this method also allows control over the structure, for example, core–shell, core–shell–shell, and so forth. However, it can be sometimes challenging to achieve only alloy particles without core–shell particles, because the magnetrons are separated from each other.…”