Supersonic cluster beam deposition of bimetallic Sn-Pt nanogranular films: nanostructure control, segregation, and 2D intermetallic phases.

Nanogranular films obtained by the soft assembly of atomic clusters feature functional properties that are of interest in a variety of fields, ranging from gas sensing to neuromorphic computing, heterogeneous catalysis and the biomedical sector. Bimetallic nanogranular films, combining a post-transition metal (tin) and a catalytic metal (platinum), were produced using supersonic cluster beam deposition. By operating the cluster source with a double-rod cathode or sintered cathode configuration, completely different nanostructures were obtained. In the first case, segregated particle families of the two metals with their specific size distributions were observed, while in the second case, the formation of 2D layered intermetallic Sn-Pt phases embedded into Sn nanoparticles was observed. These phases are compatible with the Dirac nodal arc semimetal PtSn. Chemoresistive hydrogen gas sensing measurements are reported as an example of prospective application of nanogranular films containing segregated SnO and Pt nanoparticle families.