Abstract
Single crystal X-ray structure refinements of one ideally ordered and two partially disordered dolomites provide structural data about the thermally induced, cation disordering process. Most refined parameters show progressive and gradual changes as disorder increases. It was found that completely disordered crystals could not be recovered using piston-cylinder methods owing to reordering during the quench. This factor limited the range over which disorder in quenched specimens could be studied, although some parameters are extrapolated to complete disorder. New experiments confirm that disorder is complete by 1150°C.
Electron density maps based on intensity data from specimens which exceeded the critical disordering temperature suggest CO3 group disorder of a rotational kind.
