2, Nevada National Security Site, Las Vegas, Nevada, United States
3, BOKU, Vienna, , Austria
4, SLAC National Accelerator Laboratory, Menlo Park, California, United States
5, NASA Ames, Mountain View, California, United States
6, Osaka University, Osaka, , Japan
7, Sogang University, Seoul, , Korea (the Republic of)
8, XFEL, Pohang Accelerator Laboratory, Pohang, , Korea (the Republic of)
11, HPSTAR, Beijing, , China
13, University of Edinburgh, Edinburgh, , United Kingdom
9, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
10, Technical University of Denmark, Lyngby, , Denmark
14, U.K. Atomic Energy Authority, Abingdon, , United Kingdom
12, HPSTAR, Shanghai, , China
15, CEA, Grenoble, , France
Single crystals of diamond have high mechanical strength and are very resilient to high-intensity X-ray radiation. Diamonds are thus irreplaceable in applications across X-ray optics and high-pressure physics, serving as windows, monochromators, and anvils in high pressure cells. The physics underlying diamond’s unusual properties stems from its strong sp3 covalent bonds and simple symmetry. As diamonds eventually damage under ultra-high intensity X-ray radiation, the tetrahedrally bound sp3 carbon atoms are known to graphitize to trigonal bipyramidal sp2 hybridized carbon atoms. This change in local symmetry mechanically destabilizes the material by adding low-energy pathways along which the crystal may deform. Studies of the mechanism by which high-energy X-rays graphitize diamond and the resulting changes to the mechanical properties have been limited. Few characterization techniques can measure the lattice defects and microstructure of a crystal deep beneath its surface—especially as the material responds to external stimuli.
We use ultrafast dark-field X-ray microscopy to directly image changes to the phase, strain and lattice tilt with ultra-high sensitivity as diamond responds to the high intensity X-ray radiation at an X-ray free electron laser. With these results, we demonstrate how minor changes to the microstructure of diamond from the incident radiation cascade into large-scale deformations. This work demonstrates how this novel high-sensitivity technique can give us a new view of the link between radiation and mechanical damage in diamond, informing applications across X-ray science, high-pressure science and astrophysics.
This work was performed in part under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.