Journal of Electron Microscopy 51:S219-S224 (2002)
© 2002 Oxford University Press
Full-length paper |
Ion-beam-induced structural changes in MgAl2O4 and TiO2

1The Institute of Scientific and Industrial Research, Osaka University, Mihogaoka, Ibaraki, Osaka 567-0047, Japan and
2Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
To whom correspondence should be addressed. E-mail: ishimaru{at}sanken.osaka-u.ac.jp
Microstructures of ion irradiated magnesium-aluminate spinel (MgAl2O4) and rutile (TiO2) were examined in detail using cross-sectional transmission electron microscopy (TEM). Single crystalline (111)-oriented MgAl2O4 and (100)-oriented rutile wafers were used for irradiation experiments. Based on selected area electron diffraction patterns, high-resolution TEM images, and their Fourier transforms, the following results were obtained. (1) Prior to amorphization, an ordered MgAl2O4 spinel transforms into a disordered rock salt-like phase, in which all cations reside on octahedral interstices within a pseudo-cubic close-packed oxygen anion sublattice. (2) Ion beam irradiation of rutile induces a reoriented surface layer which consists of rutile crystallites, some with the same orientation as the original substrate, and some with different orientations compared to the original single crystal.
Keywords ion irradiation, spinel, rutile, structural changes, high-resolution transmission electron microscopy, selected area electron diffraction