Figure 2: Transition from pyrolytic graphite to diamond.
From: Nanosecond formation of diamond and lonsdaleite by shock compression of graphite
X-ray diffraction data of (a) cold and (b–d) compressed pyrolytic graphite samples, driven parallel to the graphite c axis; t0 is denoting the start of the drive laser pulse. For 19 GPa, diffraction shows graphite, which is mainly compressed along the c axis, together with some cold material from the rear side of the sample not reached by the shock. For 60 GPa at exactly the moment when VISAR records the shock having traversed the whole sample, every signature from graphite vanishes. In this case, only a broad cubic diamond (111) diffraction peak remains. For higher pressures (for example, 122 GPa), the width of the peak decreases due to the reduced transition time and we observe the formation of a sharp Bragg reflection within 1 ns.
