Researchers in the Faculty of Materials Science and Engineering at the Technion have developed an innovative method for creating nanometer needles with practical potential
Technion researchers present an innovative method for creating nanometer needles. In this process, the needles are created from linear defects called dislocations that exist in metals. This is the first time that dislocations of one material form a template for creating needles of another material. The research was led by Prof. Beaz Pokroy and PhD student Lotan Portal from the Faculty of Materials Science and Engineering and the Russell Berry Nanotechnology Institute (RBNI), and it was published in the journalPNAS .
Dislocations are a significant phenomenon in materials science, as they affect the properties of the material at the micro and macro levels. For example, a high concentration of dislocations leads to an increase in the strength and hardness of the metal. The edges of the dislocations that appear on the surface of the metals, and the atoms located near these edges, tend to be more reactive in relation to the other atoms in the material and to carry out various chemical reactions such as corrosion.
The researchers in Prof. Pokroy's group created needles made of a gold-cyanide complex. In professional terms, it is a mechanism for the synthesis of inorganic systems of gold-cyanide (Au-CN) in the configuration of nano-needles that grow in an auto-catalytic process (self-catalysis of the reaction). The gold-cyanide complex is used in many fields such as ammonia (NH3) sensors, catalysis (acceleration) of conversion reactions of water from liquid to gas and more.
In a process developed by Prof. Pokroy's group, the nano-needles crystallize at the ends of the dislocations located on the surface of the original gold-silver alloy, and the resulting final structure is of classic spongy (nano-porous) gold with a layer of nano-needles growing out of it. The process of growing the needles occurs simultaneously with the process of separating the classic silver alloy from the system, and becomes possible only when the density of dislocations in the material reaches a critical value shown in the kinetic model developed in the article.
The model presented in the article provides a possible pathway for the growth of one-dimensional (1D) inorganic complexes, with possible control of the growth direction, shape and morphology of the crystal, according to the sliding systems of the original alloy. As mentioned, this scientific and technological achievement has many potential applications. The research was supported by an ERC grant from the European Commission for Research (European Union's Horizon 2020).
Link to the group's website - https://pokroylab.net.technion.ac.il/
for the article in the journal PNAS click here
