Abstract
High-temperature creep resistance in polycrystalline A12O3is highly improved by doping with 0.05 mol% lanthanoid (Ln) oxide (Ln = Sm, Eu, Tm or Lu) at 1250°C. The improvement in creep resistance probably occurs as a result of retardation of the grain-boundary diffusion in A12O3due to grain-boundary segregation of dopant cations. The change in chemical bonding state in grain boundaries with the segregation of Ln cations is examined by a first-principles molecular orbital calculation using the discrete variational-Xα method based on [Al5O21]27−model cluster. The result of the calculation indicates that the ionic bonding between Al and O ions, and the covalent bonding between Al and the surrounding cation, are strengthened by the presence of Ln ions. A correlation is found between the creep resistance and product of net charges of the constituent ions. The improved creep resistance must be explained in terms of a change in chemical bonding strength around the Al ion.
| Original language | English |
|---|---|
| Pages (from-to) | 511-525 |
| Number of pages | 15 |
| Journal | Philosophical Magazine A: Physics of Condensed Matter, Structure, Defects and Mechanical Properties |
| Volume | 82 |
| Issue number | 3 |
| DOIs | |
| Publication status | Published - 2002 Feb 1 |
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Materials Science(all)
- Condensed Matter Physics
- Physics and Astronomy (miscellaneous)
- Metals and Alloys