TY - JOUR
T1 - A change in the chemical bonding strength and high-temperature creep resistance in A12O3with lanthanoid oxide doping
AU - Yoshida, H.
AU - Yamamoto, T.
AU - Ikuhara, Y.
AU - Sakuma, T.
N1 - Funding Information:
ACKNOWLEDGEMENT The authors wish to express their gratitude to the Ministry of Education, Science and Culture, Japan, for the financial support by grants-in-aid for developmental scientific research (2)-10450254, (2)-11355028 and (2)-13750647 for fundamental scientific research.
PY - 2002/2/1
Y1 - 2002/2/1
N2 - 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.
AB - 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.
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U2 - 10.1080/01418610208239613
DO - 10.1080/01418610208239613
M3 - Article
AN - SCOPUS:3142735249
VL - 82
SP - 511
EP - 525
JO - Philosophical Magazine A: Physics of Condensed Matter, Structure, Defects and Mechanical Properties
JF - Philosophical Magazine A: Physics of Condensed Matter, Structure, Defects and Mechanical Properties
SN - 0141-8610
IS - 3
ER -