Highly ordered graphite (HOPG) to hexagonal diamond (lonsdaleite) phase transition observed on picosecond time scales using ultrafast x-ray diffraction
Abstract
The response of rapidly compressed highly oriented pyrolytic graphite (HOPG) normal to its basal plane was investigated at a pressure of ∼80 GPa. Ultrafast x-ray diffraction using ∼100 fs pulses at the Materials Under Extreme Conditions sector of the Linac Coherent Light Source was used to probe the changes in crystal structure resulting from picosecond timescale compression at laser drive energies ranging from 2.5 to 250 mJ. A phase transformation from HOPG to a highly textured hexagonal diamond structure is observed at the highest energy, followed by relaxation to a still highly oriented, but distorted graphite structure following release. We observe the formation of a highly oriented lonsdaleite within 20 ps, subsequent to compression. This suggests that a diffusionless martensitic mechanism may play a fundamental role in phase transition, as speculated in an early work on this system, and more recent static studies of diamonds formed in impact events.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Aug 01, 2022
- Source ID
- 10.1063/5.0085297
Entities
People
- Alexander Goncharov
- Arianna E. Gleason-Holbrook
- Bob Nagler
- Clemens Prescher
- Eduardo Granados
- Elissaios Stavrou
- Evan J Reed
- Hae Ja Lee
- Harry B. Radousky
- Inhyuk Nam
- Jonathan L Belof
- Matthew P Kroonblawd
- Michael R. Armstrong
- Nicholas Holtgrewe
- Nir Goldman
- Oliver Tschauner
- Paulius Grivickas
- Peter Walter
- Ryan A. Austin
- Sergey Lobanov
- Shaughnessy Brennan Brown
- Vitali Prakapenka
Organizations
- Army Research Office
- Carnegie Institution for Science
- Defense Threat Reduction Agency
- Division of Earth Sciences
- Lawrence Livermore National Laboratory
- SLAC National Accelerator Laboratory
- Stanford University
- United States Department of Energy
- University of Freiburg
- University of Nevada, Las Vegas
- University of Potsdam