In situ TEM observation of decomposition of high-purity sapphire

摘要

The decomposition of alpha-Al_2O_3 under 200 keV electron irradiation has been investigated by in situ high-resolution electron microscopy (HREM). It was confirmed that aluminium precipitated from alpha-Al_2O_3 under 200 keV electron irradiation for less than 1 min over the temperature range from 700 to 1273 K. The electron dose rate was of the order of 10~(23)em~(-2)s~(-1) and the vacuum level of the microscope was better than 10~(-6)Pa. The mechanisms of alpha-Al_2O_3 decomposition were discussed based on two possible decomposition models: the thermally activated atom movement and the forced atom displacement.