抄録
We directly observed laser shock-induced, anomalous elastic compression of highly oriented pyrolytic
graphite (HOPG) and subsequent phase transition to lonsdaleite at a longitudinal stress of ~30 GPa using
an X-ray Free Electron Laser (XFEL). The observed phase transition is diffusionless and most likely
relaxes a strong shear stress in the highly elastically compressed lattice. Our experimental results show
that this diffusionless transformation depends on the mosaic spread of Highly Oriented Pyrlolytic
Graphite (HOPG) samples.