Geomimetic Approaches in the Design and Synthesis of Ordered L10-Type Structure Platinum-Based Noble High-Entropy Alloys at Low Temperature

Abstract

The recent discovery of new Pt-based minerals has opened up the opportunity to generate new synthetic materials. Here, geologically inspired approaches to designing and synthesizing novel platinum alloys, from ternary to high-entropy alloys (HEAs), are showcased. Empirical mathematical models of thermodynamic parameters were used to predict the formation of solid solutions with single-phase structures in the (Pt_3–xPd_x)(Cu_2–yNi_ySn) system. Five new single-phase compounds, having ordered L1₀-type structures, have been obtained at comparatively low temperatures by solid-state reactions. Two of those phases are new noble metal HEAs, (Pt₂Pd)(Cu_1.7Ni_0.3Sn) and (Pt₂Pd)(Cu_1.4Ni_0.6Sn). Additionally, other three new multiprinciple element alloys (mixture of ordered L1₀-type and disordered FCC-type structures) were also obtained. SEM/EDX measurements gave no indication of chemical inhomogeneities on a micrometer length scale. A phase diagram is proposed. All products are thermally stable at up to 1100 K, and the two-phase samples show a tendency for nitrogen absorption. The results show that using geomimetic approaches in the design and synthesis of novel materials opened new opportunities for future materials design.