关键词: 单质非晶金属, 玻璃形成, 五重对称, 纳米限域, DNA 折纸

Abstract: Elemental amorphous metals, composed of a single metallic element, provide important model systems for investigating fundamental aspects of glass formation, local atomic structure, and crystal nucleation and growth. Unlike multicomponent alloys, elemental metals generally have well-defined and thermodynamically stable crystalline structures, and their crystallization does not require long-range compositional diffusion. They therefore crystallize readily, making the amorphous state exceptionally difficult to obtain. Experimentally realized elemental amorphous metals have so far been found mainly in low-dimensional forms, such as thin films and nanoparticles. This review summarizes the principal synthesis methods, structural characteristics, and discusses their glass formation from the perspectives of rapid cooling, interfacial and size effects, and competition among local atomic configurations. Particular attention is given to our recent work on the formation of amorphous Ag using a near-fivefold-symmetric DNA-origami template. Under ambient temperature and pressure, an amorphous Ag region approximately 3 nm in size forms at the center of the template. Template-free control experiments, time-resolved observations under electron-beam irradiation, and molecular-dynamics simulations with different boundary symmetries show that nanoscale confinement together with near-fivefold geometrical constraints can effectively suppress crystal nucleation in Ag, providing a new route to the formation of amorphous elemental metals. Finally, we discuss current approaches to structural identification, the mechanisms underlying amorphous formation, and the relationship between structure and properties in elemental amorphous metals, and highlight several questions that remain to be resolved.