Abstract
Single crystal X-ray diffraction studies under virtually extinction-free conditions have been carried out using 10-micrometer-sized small crystals and the synchrotron radiation at the beamline 14A, Photon Factory, KEK. A case study for CaYAIO4 is described. Results were compared with those obtained by the conventional rotating-anode four-circle diffractometer using Ag Kα. It' was revealed that the extinction-correction included in the least-squares procedure sometimes causes serious artefacts in the deformation density maps and may lead to incorrect interpretation. Collection of virtually extinction-free diffraction data is indispensable for precise structure analyses to elucidate structures containing a lesser degree of disorder, as well as for charge density analyses.
