Dopant effect on grain boundary diffusivity in polycrystalline alumina

Journal Article · Mon Jan 10 04:00:00 EST 2005 · Acta Materialia

DOI:https://doi.org/10.1016/j.actamat.2004.09.038· OSTI ID:20637126

Yoshida, Hidehiro ^[1]; Hashimoto, Shinsuke ^[2]; Yamamoto, Takahisa ^[2]

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1. Fine-grained Refractory Materials Group/ICYS, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan)
2. Department of Advanced Materials Science, School of Frontier Science, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa Chiba 277-8581 (Japan)

The densification behavior during sintering in 0.1 mol% MgO-, MnO-, SrO-, LuO{sub 1.5}-, TiO{sub 2}-, ZrO{sub 2}- or PtO{sub 2}-doped Al{sub 2}O{sub 3} was investigated at the sintering temperature of 1300-1500 deg C in order to systematically examine the dopant effect on grain boundary diffusivity in Al{sub 2}O{sub 3}. The densification behavior was monitored from room temperature to the sintering temperature using a laser-scanning system, which allows in situ, non-contact measuring of the specimen's dimensions. The grain boundary diffusivity in Al{sub 2}O{sub 3} is sensitively affected by the dopant cation which segregates at the grain boundaries. The dopant effect on the grain boundary diffusivity is related to the ionicity in Al{sub 2}O{sub 3}; a lower energy level of the dopant element's outer shells provides a higher value of diffusivity in the divalent or tetravalent cation-doped Al{sub 2}O{sub 3}. A first-principle molecular orbital calculation revealed that the grain boundary diffusivity correlates well with the net charge of the Al and O ions in the cation-doped Al{sub 2}O{sub 3}. The ionic bond strength in the vicinity of the grain boundaries dominates the high-temperature grain boundary diffusion in polycrystalline Al{sub 2}O{sub 3}.

• OSTI ID: 20637126
• Journal Information: Acta Materialia, Journal Name: Acta Materialia Journal Issue: 2 Vol. 53; ISSN 1359-6454; ISSN ACMAFD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM OXIDES
BOUND STATE
CATIONS
DIFFUSION
DOPED MATERIALS
ENERGY LEVELS
GRAIN BOUNDARIES
LUTETIUM OXIDES
MAGNESIUM OXIDES
MANGANESE OXIDES
OXYGEN IONS
PLATINUM OXIDES
POLYCRYSTALS
SINTERING
STRONTIUM OXIDES
TEMPERATURE RANGE 0273-0400 K
TITANIUM OXIDES
ZIRCONIUM OXIDES