The effects of the Zr doping in fine-grained alumina (α-Al2O3) on fine structures are studied. The combination of high-resolution transmission electron microscopy (HRTEM) and field emission scanning transmission electron microscopy has been a powerful tool for material investigations and it was employed to investigate grain-boundary structures, chemical composition and chemical bonding of 1000 ppm Zr-doped polycrystalline α-Al2O3. HRTEM revealed that the atomic structure of grain-boundary regions was not strongly distorted from that of the surrounding bulk, α-Al2O3. It was found that there was no amorphous phase at any grain boundaries. Energy-dispersive X-ray spectroscopy (EDS) and electron—energy-loss spectroscopy in a dedicated scanning transmission electron microscope used for analytical investigations provided spatial difference information about elemental-composition since the electron probe size in the scanning transmission electron microscope is as small as 3 Å. It was shown by the EDS that Zr segregated in the grain-boundary regions with the Zr-to-Alatomic ratio of 1.6 ± 0.2%. Normalization and subtraction of the matrix spectra from the interface spectra yield grain-boundary-sensitive near-edge structure of energy-loss near-edge structure (ELNES). Similar features are found for both the OK edge and the Al L2.3 edge ELNES at the boundary. The origin of these features is ascribed to the heavily misshapen defects at the random boundary.
|ジャーナル||Philosophical Magazine A: Physics of Condensed Matter, Structure, Defects and Mechanical Properties|
|出版ステータス||出版済み - 5 1998|
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