No abstract

Emerging functional room-temperature liquid metals generally include gallium-based and bismuth-based alloys. Their excellent electrical conductivity, thermal conductivity, flexibility, fluidity, and reflectivity can enable their application in many fields. However, there are quite a few problems that need to be solved before their application. For example, liquid metals are often difficult to adhere and diffuse on solid substrates due to their high surface tension and fluidity, which hinders the application and promotion. Herein, we report a method to develop multiphase soft metals from gallium- and bismuth-based alloys. Particularly, room-temperature multiphase soft metals of GaBiInSn alloys developed from Ga67In20.5Sn12.5 and Bi33.1In51.3Sn15.6 alloys via compositing, mixing, and heating treatment are first reported, which include the solid phase, liquid phase, and paste phase, respectively. The free metal alloy grains are dispersed in GaBiInSn alloys and transition constantly among different phases. More importantly, the structure, size, density, and other characteristics of free metal alloy grains can be modified by adjusting the mass ratio of each component. The surface morphology, structure, wettability, adhesion, work function, and photoelectric characteristics of multiphase soft metals can be controlled and optimized by controlling phase transition. As a result, the wettability of the obtained Ga50.25Bi8.28In28.2Sn13.27 is obviously improved (the contact angle decreased from 118.5° to 94°), with a high work function (4.75 eV), high reflectivity (78.14%), low electrical resistivity (2.94 × 10–7 Ω m). Meanwhile, several typical applications of the multiphase materials were demonstrated. The results of this work will offer a promising strategy to directly prepare liquid metal flexible electrodes on PI, PET, and silk, and also, the stability can be kept well under large deformation and curling conditions.

Liquid metals (LMs) have emerged as promising functional materials that combine the properties of both liquid and metal. These characteristics enabled them to find applications in many fields. However, the LMs usually can only display a silver-white physical appearance, which limits their further applications in the fields with the imposition of stringent requirements for color and aesthetics. Herein, we report that the surface of LMs was transformed directly from metal to fluorescent semiconductor layer by an example of eutectic GaInSn (eGaInSn) induced by thermal oxidation. Specifically, a core–shell structure is formed from the fluorescent layer and the LMs. The shell endows the LMs with fluorescence without affecting their interior fluidity and conductivity. In particular, the formation process as well as the degree of crystallization, phase transformation, and light emission of the fluorescent oxide shell on the surface of LMs is regulated by the component content. A thorough analysis of surface morphology, composition, structure, and properties of the fluorescent shell suggests that the Ga2O3 layer is formed on the surface of gallium-based LMs after their immersion in deionized water. Subsequently, thermal oxidation results in the formation of the β-Ga2O3 shell on the surface of liquid metals. Importantly, abundant oxygen vacancies (VO) in β-Ga2O3 as the donors and the gallium vacancies (VGa), gallium–oxygen vacancy pairs (VO–VGa), defect energy levels, and intrinsic defects as the acceptors enabled the light emission. The fluorescent LMs have promising potential for flexible lighting and displays, anticounterfeiting measures, sensing, and chameleon robots.

Cocrystallization has been applied widely for material synthesis. Recently cocrystal of organic molecules has been developing rapidly, taking the advantages of the flexibility and self-assembly of organic molecules. Here we report an experimental study of a cocrystal of copper-phthalocyanines and fluorinated ones. We have grown the samples via the vapor-phase deposition of the mixture with different mass ratios from 1:13.5 to 6:1. As suggested by our scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman spectroscopy, new crystal structures and morphologies through our novel strategy for the cocrystallization of these molecules have been found. Our work will provide a solid foundation to systematically synthesize the cocrystal of phthalocyanine molecules with new crystal structures, thus providing the opportunity to advance material properties.

The further applications of liquid metals (LMs) are limited by their common shortcoming of silver‐white physical appearance, which deviates from the impose stringent requirements for color and aesthetics. Herein, a concept is proposed for constructing fluorescent core–shell structures based on the components and properties of LMs, and metal halides. The metal halides endow LMs with polychromatic and stable fluorescence characteristics. As a proof‐of‐concept, LMs‐Al obtained by mixing of LMs with aluminum (Al) is reported. The surface of LMs‐Al is transformed directly from Al to a multi‐phase metal halide of K3AlCl6 with double perovskites structure, via redox reactions with KCl + HCl solution in a natural environment. The formation of core–shell structure from the K3AlCl6 and LMs is achieved, and the shell with different phases can emit a cyan light by the superimposition of the polychromatic spectrum. Furthermore, the LMs can be directly converted into a fluorescent shell without affecting their original features. In particular, the luminescence properties of shells can be regulated by the components in LMs. This study provides a new direction for research in spontaneous interfacial modification and fluorescent functionalization of LMs and promises potential applications, such as lighting and displays, anti‐counterfeiting measures, sensing, and chameleon robots.