Generating pressures of 500 GPa using nanocrystalline diamond as second stage anvils
Single crystal diamond is the hardest known material and widely used in studies on materials under extreme conditions. Nanocrystalline diamond (NCD) possesses hardness comparable to that of single crystal diamond, while also demonstrating increased fracture toughness and yield strength. Thus, NCD’s is a candidate material as second stage anvils to extend the maximum pressure in static high pressure technology. A research team, using Microwave Plasma Chemical Vapor Deposition, has successfully grown NCD on single crystal diamond anvil surface (Figure). The team used HPCAT facility and is able to generate static pressure of 500 GPa (0.5 TPa) on a tungsten sample as measured by synchrotron x-ray diffraction using the grown NCD as second stage micro-anvils. Atomic force microscopy analysis after decompression from ultrahigh pressures showed that the detachment of the NCD stage occurred in the bulk of the SCD and not at the interface, suggesting significant adhesive bond strength between nanocrystalline and single crystal diamond anvil. More in S.L. Moore, et al., Sci. Rep., 8, 1402, 2018.