Scientists at UNIST have developed a new novel method to grow elastic diamonds and their study has been published in journal Science.
Researchers say that brittle diamonds can be bent and stretched elastically when made into ultrafine needles. The team demonstrated that their nanoscale diamond needles could flex and stretch by as much as nine percent without breaking, then return to their original shape. The team is optimistic that their work could open up unprecedented possibilities for tuning its optical, optomechanical, magnetic, phononic, and catalytic properties through elastic strain engineering.
Ordinary diamond in bulk form has a limit of well below one percent stretch, according to the researchers. In the study researchers handled the chemical calculation and the analysis of the crystal structure of diamond and ascribed that the ultrahigh elasticity of the diamond nanoneedles is due to the paucity of internal defects and the relatively smooth surface.
Via detailed simulations researchers determined precisely how much stress and strain the diamond needles could accommodate without breaking. They determined the corresponding maximum local stress was close to the known theoretical limit achievable with a perfect, defect-free diamond. He noted that defect-free diamonds can stretch by as much as 12% without breaking.
The research team from the City University of Hong Kong succeeded in fabricating nanoscale diamond needles by plasma-induced etching of diamond thin films deposited on Si substrates through bias-assisted chemical vapor deposition (CVD). As a result, the team was able to demonstrate ultralarge, fully reversible elastic deformation of nanoscale (~300 nanometers) single-crystalline and polycrystalline diamond needles.
The team measured the bending of the diamond needles, which were grown through a chemical vapor deposition process and then etched to their final shape, by observing them in a scanning electron microscope while pressing down on the needles with a standard nanoindenter diamond tip. They demonstrated experimentally that single-crystalline needles are simultaneously ultrastrong and susceptible to large elastic deformation, with fully reversible mechanical deformability of up to a maximum of 9% of elastic tensile strain.
The research team expects that their findings could lead to performance enhancement in applications, involving bioimaging and biosensing, strain-mediated nanomechanical resonators, drug delivery, data storage, and optomechanical devices, as well as ultrastrength nanostructures.