Chinese scientists have proposed a new method for direct fabrication of sub-10 nm nanopores in WO3 nanosheets using heavy ions are fast these days. The results have been published in Nano Letters.
The study was carried out by scientists at the Materials Research Center of the Institute of Modern Physics (IMP) of the Chinese Academy of Sciences (CAS) and their collaborators at the Joint Institute for Nuclear Research, Russia.
Fabrication of high quality solid-state nanopores is critical for single molecule detection applications, nanofluid devices and nanofiltration membranes. The most popular way to make nanopores in inorganic films, such as SiN, SiO2 and Al2HI3is to use a focused ion or electron beam.
However, a feedback system or direct imaging is required using this poring method, and only one nanopore can be created at a time, which limits mass production. Therefore, it is necessary to explore new poring methods that can create nanopores whose size and density can be controlled without a feedback system.
Based on the Heavy Ion Research Facility in Lanzhou (HIRFL), scientists have demonstrated the direct pore method in WO3 nanosheets using fast heavy ion irradiation.
Moreover, they applied molecular dynamics simulations to elucidate the underlying mechanisms. It was found that the viscosity and surface tension of the transient liquid phase induced by the fast heavy ions are key factors for the formation of nanopores.
By selecting ions from a variety of electronic energy losses, the scientists created nanopores with sizes from 1.8 to 7.4 nm in WO.3 nanosheets. They can control the density of the nanopores by applying different ionic influences.
This new poring method, which does not involve a chemical etching process, has certain potential for wide application. This opens the way to fabricate solid nanopores in materials with low viscosity and surface tension using fast heavy ions, providing new insights into the formation of latent ion pathways in solid materials.