In Situ Observation of the Phase Transition Behavior of Shocked Baddeleyite

Baddeleyite (ZrO2) is used to infer shock pressures and understand the impact history of planetary bodies. Although the high-pressure phase transition behavior of baddeleyite has been intensively investigated under hydrostatic conditions, there is little information on the dynamic response of phase transitions under shock-loading conditions. We performed in situ X-ray diffraction measurements on shock-loaded baddeleyite using a synchrotron X-ray pulse at beamline NW14A of the Photon Factory Advanced Ring, High Energy Accelerator Research Organization (KEK), Japan. A phase transition from monoclinic to orthorhombic-I ZrO(2)occurs at 3.3 GPa during shock compression and immediately returns to the monoclinic phase during subsequent release. Orthorhombic-II ZrO(2)is not observed up to 15 GPa. This study refines the phase transition behavior of baddeleyite under shock conditions up to 15 GPa, and the phase transition boundary is determined from direct observations. These findings improve the understanding of the shock history of planetary bodies.