Metals can be squeezed into sheets just a few atoms thick

Scientists Develop Technique to Create Two-Atom-Thick Metal Sheets

Scientists have successfully developed a groundbreaking technique that enables the creation of metal sheets just two atoms thick. By subjecting molten droplets to high pressure between two sapphire crystals, these thin metal sheets could have significant implications across various industries including industrial chemistry, optics, and computing.

Previously, researchers had managed to produce a single-atom-thick gold sheet, referred to as “goldene,” inspired by graphene, a material composed of a single layer of carbon atoms. However, the production of other 2D metals had proven to be a challenge until now. The innovative technique, pioneered by Luojun Du and his team at the Chinese Academy of Sciences, can now generate 2D sheets of metals such as bismuth, gallium, indium, tin, and lead that are as thin as their atomic bonds permit.

The process involves using two flat sapphire crystals with a thin layer of molybdenum disulfide (MoS₂) as a vice to compress the metal. The powdered metal is heated to 400°C to form a droplet, which is then crushed at pressures of up to 200 megapascals. The metal is compressed to a thickness of just a few atoms, with bismuth reaching a remarkable two-atom thickness. After cooling, the 2D metal is sandwiched between the MoS₂ layers, which easily detach from the sapphires once the pressure is released.

Although the concept for this process was conceived eight years ago, it was only recently that the team discovered the stabilizing effect of the MoS₂ layers on the thin metal sheets. According to Du, the development of entirely new techniques was essential due to the inherent instability of a single layer of free-standing metal atoms. Despite its apparent simplicity, the process has proven to be highly effective.

In addition to creating ultra-thin layers of atoms, the researchers were able to precisely adjust the pressure to produce metal plates with varying thicknesses, ranging from three to four atoms thick. Du believes that these 2D metals could exhibit unique properties that could facilitate the exploration of macroscopic quantum phenomena and superconductivity. Furthermore, they could potentially lead to the development of ultra-low power transistors, transparent displays for computers, and highly efficient catalysts for chemical reactions.

One challenge associated with the MoS₂ encapsulation of the metal sheet is the difficulty in removing it. However, experiments have shown that this does not hinder electrical conductivity, making the 2D metal suitable for use in electronic devices.