The (100), (110) and (111) planes were studied by using atomic force microscopy. It was noted that the surface structures were different to the bulk ones, and that surface defects existed on each surface. It was suggested that the surface free energy and polarization played an important role in altering the surface structures. It was concluded that all of the bright spots in the atomic force microscopic images corresponded to the positions of O atoms.

H.Takeda, M.Tsujimoto, K.Nogi, T.Sakata, K.Ogino: Journal of the Japan Institute of Metals, 1993, 57[5], 555-60