Combined energy dispersive x-ray absorption and diffraction under high pressure

Abstract

Combined x-ray absorption spectroscopy (XAS) and x-ray diffraction experiments (EDX) on powders, both in the dispersive mode, may enable the determination of structural parameters as a function of pressure. After phase transitions, it may even be possible to determine the structure of the high pressure phases. The EDX enables the determination of the cell parameters, and eventually the space group from the systematic extinctions. On the other hand, the XAS provides information on the local environment of an atomic species, i.e., the coordination number and the first (eventually even second) neighbour distances with a high precision.

The combination of these two techniques has been successfully used to determine the high pressure structure of ZnTe and HgTe. We present here recent results obtained on the high pressure properties of chalcopyrites and of berlinites. Finally, recent developments and future possibilities with the new synchrotron sources are presented.

Key Words:

• X-ray absorption
• x-ray diffraction
• high pressure
• GaPO₄