Stability of rocksalt phase of zinc oxide under strong compression: Synchrotron X-ray diffraction experiments and first-principles calculation studies

The stability of rocksalt (B1) phase of ZnO under high pressure up to 2 Mbars was studied using angular dispersive x-ray diffraction at room temperature and compared to the structurally analogous CdO where both theoretical and experimental results are available. First-principles total energy calculations predict the B1-to-B2 (CsCl-type) phase transition in ZnO and CdO to occur at 261 and 83 GPa, respectively. The bulk moduli, K-0, of the B1 structure of ZnO were measured and the possible high pressure CsCl-type (B2) structure was looked for. The potential application of ZnO as an internal pressure marker in x-ray diffraction study at the megabar range is proposed. (c) 2006 American Institute of Physics.