Regensburg 2013 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 18: Computational Materials Modelling - Phase Stability I

MM 18.2: Vortrag

Dienstag, 12. März 2013, 10:30–10:45, H24

A joint DFT and experimental study of the competing phases of Calcium at high-pressures and low-temperatures — •Deepa Kasinathan¹, Carina Boerrnert¹, Michael Hanfland², Jens Hunger¹, Helge Rosner¹, and Ulrich Schwarz¹ — ¹MPI CPfS-Dresden — ²ESRF, Grenoble

One of the most unanticipated developments in superconducting critical temperatures (T_c) in the past decade has been the achievement of much higher values of Tc in elemental superconductors by the application of high pressure. Surprisingly, these superconducting states evolve from simple metals that are non-superconducting at ambient pressure. Calcium undergoes a series of structural changes under pressure and superconducts with a T_c as high as 26 K near 160 GPa. There has been a long standing discrepancy among and between various experiments and as well as density functional theory based calculations to correctly identify the various high-pressure phases in calcium. Here, we report on a combined experimental and theoretical work on the multitude of structural phase transitions observed at low-temperatures and high-pressures. In our study, we have performed high-pressure X-ray diffraction experiments at the ESRF synchrotron beam-line (ID09A) to examine, verify and validate the complex phase diagram of calcium.