Metastable Bi under extreme conditions investigated by combined XAS and XRD

We report the results of a detailed experimental study carried out at the European Synchrotron Radiation Facility (ESRF) providing an unprecedented insight into the metastable phase diagram of Bi. In particular we focus the attention on a novel metastable crystalline structure of Bi compatible with the beta-tin structure. It is reasonable to identify the new structure with the unknown stable Bi-II' structure. These findings have been achieved using the single energy x-ray absorption detection (SEXAD) technique and angular dispersive x-ray diffraction (ADXD) both combined with a "Paris-Edinburgh" V5 large volume press at the BM29 beamline. The results obtained show that the combination of SEXAD and ADXD is a unique and reliable tool for detecting subtle structural modifications in condensed matter.