Seminars Archive

Crystal structure and phase transitions in leucites. Past, present and future.

Abstract
Synchrotron X-ray powder diffraction, in conjunction with MAS-NMR, electron diffraction and neutron powder diffraction, have been used to study the crystal structures of synthetic analogues of the silicate tetrahedral framework mineral leucite (KAlSi2O6). Two previously unknown ambient temperature leucite crystal structures, with ordered framework cations, have been determined at room temperature. A high temperature phase transition has also been observed in which the leucite crystal structure changes from ordered to disordered framework cations. A previously unknown crystal structure has been determined above this phase transition temperature.