Pressure-induced structural transitions at low temperature conditions

The researches on high pressure induced phase transitions are long time hot topics in condense matter physics. Many interesting behaviors, such as high Tc superconductivity, were reported recently, but the responsible structures are not well studied at correct P-T conditions and far away from fully understood. In this presentation, several selected systems were in situ studied, including powder and single crystal samples, under high pressure using lab base and synchrotron x-ray diffraction (XRD) techniques in diamond anvil cell at ambient temperature and low temperature conditions, will be presented. Selected cases, such as elements with record high Tc (Ti and Sc), metal hydrides (Ca-H, Lu-H, Hf-H), La-Ni-O system, would be discussed based on the recent XRD results and the first principle calculations, and then propose the possible general trend for their phase diagrams at low temperature and high pressure region.