Epitaxial Growth of a Gold Shell on Intermetallic FeRh Nanocrystals

In contrast with bimetallics, multimetallic nanoparticles (NPs) can combine different chemical orders in the same NP, which favors an enhanced tuning of their properties. In this work, trimetallic (Fe, Rh, Au) nanocrystals with controlled composition and chemical distribution were grown through a physical vapor deposition route using a two-step process. First FeRh nanocrystals, 8.5 nm of mean diameter, were formed according to a Volmer-Weber growth mode. The growth conditions were tuned so as to achieve the atomic scale chemical order displayed by the intermetallic B2-FeRh phase. Then the gold layer was deposited at a lower temperature. Evidence is given for the complete coverage of the gold shell, which grows epitaxially over the B2-FeRh core exposed facets. These different features are particularly promising for further applications.