Gallium-Based Liquid Metal Amalgams: Transitional-State Metallic Mixtures (TransM²ixes) with Enhanced and Tunable Electrical, Thermal, and Mechanical Properties

Metals are excellent choices for electrical- and thermal-current conducting. However, either the stiffness of solid metals or the fluidity of liquid metals could be troublesome when flexibility and formability are both desired. To address this problem, a reliable two-stage route to improve the functionalities of gallium-based liquid metals is proposed. A series of stable semiliquid/semisolid gallium-based liquid metal amalgams with well-controlled particle packing ratios, which we call TransM²ixes, are prepared and characterized. Through effectively packing the liquid metal with copper particles (which are found to turn into intermetallic compound, CuGa₂, after dispersing), remarkable enhancements in electrical conductivity (6 × 10⁶ S m^-1, ∼80% increase) and thermal conductivity (50 W m^-1 K^-1, ∼100% increase) are obtained, making the TransM²ixes stand out from current conductive soft materials. The TransM²ixes also exhibit appealing semiliquid/semisolid mechanical behaviors such as excellent adhesion, tunable formability, and self-healing ability. As a class of highly conductive yet editable metallic mixtures, the TransM²ixes demonstrate potential applications in fields like printed and/or flexible electronics and thermal interface materials, as well as other circumstances where the flexibility and conductivity of interfaces and connections are crucial.