Detection of Sixfold Co-ordinated Si at Grain Boundaries of Sintered α-Al_2O_3

摘要

High-resolution transmission electron microscopy and analytical electron microscopy have been carried out on Si-doped sintered α-Al_2O_3. High-Resolution Transmission Electron Microscopy (HRTEM) shows that there is no amorphous phase at grain boundaries. Si was found significantly segregated at grain boundaries, electron microscopy with Electron Energy Loss Spectroscopy (EELS) reveals the existence of sixfold co-ordinated Si at the grain boundaries for the first time. The results of theoretical calculations, by molecular orbital method, support the one obtained by electron energy loss spectroscopy.