Studies of phase transitions in PETN at high pressures

We have performed X-ray powder diffraction experiments in the 0–36 GPa region and investigated phase transitions in the high-explosive, pentaerythritol tetranitrate (PETN) using different pressurizing media (nitrogen, no medium (neat)) and different rates of compression. The results provide strong evidence on the role of sheer stress in the initiation of phase transitions in the material, observed around 7 GPa during compression of the neat material.