Low-temperature polyol synthesis of AuCuSn₂ and AuNiSn ₂: Using solution chemistry to access ternary intermetallic compounds as nanocrystals

Ternary intermetallic compounds, which possess a wide variety of important properties with both academic and technological relevance, are typically synthesized using traditional high-temperature methods. Here, we demonstrate that the polyol method, which is used extensively to synthesize nanocrystals and nanocrystalline powders of metals and simple binary compounds, serves as an effective low-temperature exploratory medium for synthesizing new ordered ternary intermetallics as nanocrystals. Accordingly, we describe the synthesis and structural characterization of AuCuSn₂ and AuNiSn₂, which adopt an ordered NiAs-type superstructure that is not observed using equilibrium synthetic methods. AuCuSn₂ forms in solution of 120 °C as well-formed nanocrystals, and the ordered phase is stable up to 450 °C. AuNiSn₂ behaves similarly to AuCuSn₂.