Superplastic flow stress and electronic structure in yttria-stabilized tetragonal zirconia polycrystals doped with GeO{sub 2} and TiO{sub 2}

Journal Article · Mon Nov 08 04:00:00 EST 2004 · Acta Materialia

DOI:https://doi.org/10.1016/j.actamat.2004.08.017· OSTI ID:20634806

Kuwabara, Akihide ^[1]; Nakano, Manabu ^[2]; Yoshida, Hidehiro ^[3]; Ikuhara, Yuichi ^[4]; Sakuma, Taketo ^[2]

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1. Department of Materials Science and Engineering, Kyoto University, Yoshida, Sakyo-ku, Kyoto 606-8501 (Japan)
2. Department of Advanced Materials Science, Graduated School of Frontier Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)
3. Natinal Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan)
4. Institute of Research Innovation, School of Engineering, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656 (Japan)

Superplatic flow in 3 mol%-yttria-doped tetragonal zirconia polycrystal (3Y-TZP) with tetravalent cation, Ge and Ti, has been examined by high temperature tensile testing. These cations are effective to suppress the flow stress of 3Y-TZP and to improve tensile ductility. First principles molecular orbital calculations using model clusters reveal that substituted Ge and Ti ions have strong covalent bonds with neighboring oxygen ions than Zr ion. Such high covalency of Ge-O and Ti-O bonds is due to large bonding components in valence band. Addition of Ti and Ge ions leads to reduction in the ionicity in 3Y-TZP. From our high temperature tensile tests and theoretical calculations for GeO{sub 2}- and TiO{sub 2}-doped TZP, flow stress is observed to correlate with an effective ionic bonding strength. It is expected that the ionicity is a major parameter to control the diffusivity of cation and to hence affect the superplastic flow of 3Y-TZP.

• OSTI ID: 20634806
• Journal Information: Acta Materialia, Journal Name: Acta Materialia Journal Issue: 19 Vol. 52; ISSN 1359-6454; ISSN ACMAFD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BOUND STATE
COVALENCE
DOPED MATERIALS
DUCTILITY
ELECTRONIC STRUCTURE
FLOW STRESS
GERMANIUM IONS
GERMANIUM OXIDES
OXYGEN IONS
PLASTICITY
POLYCRYSTALS
TITANIUM IONS
TITANIUM OXIDES
VALENCE
ZIRCONIUM IONS
ZIRCONIUM OXIDES