The structural behaviour of CuInSe(2) under high pressure has been studied up to 53 GPa using angle-dispersive x-ray powder diffraction techniques. The previously reported structural phase transition from its ambient pressure tetragonal structure to a high pressure phase with a NaCl-like cubic structure at 7.6 GPa has been confirmed. On further compression, another structural phase transition is observed at 39 GPa. A full structural study of this high pressure phase has been carried out and the high pressure structure has been identified as orthorhombic with space group Cmcm and lattice parameters a = 4.867(8) Å, b = 5.023(8) Å and c = 4.980(3) Å at 53.2(2) GPa. This phase transition behaviour is similar to those of analogous binary and trinary semiconductors, where the orthorhombic Cmcm structure can also be viewed as a distortion of the cubic NaCl-type structure.

identifying known polymorphs of organic molecules, but also completely new polymorphs, and solvates, as illustrated by the nootropic drug piracetam, for which new polymorphs and hydrates were prepared and characterised at pressures below 1.0 GPa [3].We believe that this methodology has the potential to make a significant impact for the discovery of new polymorphs and solvates.

To support various applications for high-pressure research in Thailand, an experimental setup for X-ray powder diffraction under high-pressure conditions using synchrotron radiation, which is based on station 9.1 at the Daresbury Synchrotron Radiation Source, is being developed on the bending magnet beamline BL8 at the Siam Photon Laboratory. Monochromatic X-rays with a photon energy of 9 keV are provided by a fixed-exit double crystal monochromator equipped with Ge(220) crystals. In a recent experiment, we could record a complete diffraction pattern of the hexagonal phase of ZnO using an image plate area detector. However, diffraction intensity should be improved by adding focusing optics. In this work, we propose the use of a double multilayer monochromator in combination with a focusing mirror. Results from ray-tracing simulation for the proposed optics will be presented.

No abstract