Koala
(Laue diffractometer)
Dr Michael Gardiner of the University of Tasmania undertakes research in organometallic chemistry which has applications in catalysis, synthesis and materials. His first proposal for neutron beam-time on KOALA sought to establish whether a material prepared by M.Sc. student Anung Riapanitra contains an hydridic ligand. We are also tackling the question whether the two structures determined via X-ray diffraction for this material are actually distinct structures and whether the material is polymorphic.
Neutron diffraction images were collected at 150K (top) and 100K (bottom) demonstrating that a change of structure to one with a unit cell of doubled volume occurs on cooling. The reversibility of this phase change was demonstrated by cycling between the two temperatures with no apparent loss of crystallinity thus demonstrating that the two structures correspond to different phases of a single chemical compound. Data collection on the higher temperature phase has been completed and the results are being prepared for publication. Further experiments are envisaged to probe the specifics of the transformation to the low temperature phase.
Spot the difference: One material, two different diffraction patterns, a case of a polymorphic catalyst.