A change in the chemical bonding strength and high-temperature creep resistance in A12O3with lanthanoid oxide doping

H. Yoshida, T. Yamamoto, Y. Ikuhara, T. Sakuma

Research output: Contribution to journalArticlepeer-review

27 Citations (Scopus)

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 languageEnglish
Pages (from-to)511-525
Number of pages15
JournalPhilosophical Magazine A: Physics of Condensed Matter, Structure, Defects and Mechanical Properties
Volume82
Issue number3
DOIs
Publication statusPublished - 2002 Feb 1
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Materials Science(all)
  • Condensed Matter Physics
  • Physics and Astronomy (miscellaneous)
  • Metals and Alloys

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