2004 Fiscal Year Final Research Report Summary
DESIGN OF CERAMICS BY COTROLLING GRAIN BOUNDARY CHARACTER AND QUANTUM STRUCTURES
| Project/Area Number |
14205100
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Structural/Functional materials
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| Research Institution | The University of Tokyo |
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Principal Investigator |
IKUHARA Yuichi The University of Tokyo, Graduate School of Engineering, Professor, 大学院・工学系研究科, 教授 (70192474)
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| Co-Investigator(Kenkyū-buntansha) |
MATSUNAGA Katsuyuki The University of Tokyo, Graduate School of Engineering, Assistant Professor, 大学院・工学系研究科, 助手 (20334310)
IWAMOTO Chihiro Kumamoto University, The Faculty of Engineering, Associate Professor, 工学部, 助教授 (60311635)
YAMAMOTO Takahisa The University of Tokyo, Graduate School of Frontier Sciences, Associate Professor, 大学院・新領域創成科学研究科, 助教授 (20220478)
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| Project Period (FY) |
2002 – 2004
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| Keywords | Grain boundary character / Bicrystal / Tricrystal / Ceramics / High resolution Electron Microscopy / Dopant / Grain boundary sliding / Grain boundary sliding |
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| Research Abstract |
The effect of grain boundary character on the properties in oxide ceramics by using bicrystals and tricrystals. The bicrystals of Al_2O_3,ZrO_2,ZnO and SrTiO_3 have systematically fabricated, and the grain boundary atomic structures, chemical bonding state and composition were characterized by HREM, EELS and EDS. In addition, the grain boundary energy, creep behavior and electronic properties in the respective bicrystals were measured, and the relationships of grain boundary structures, chemistry and properties were clarified from the view point of grain boundary character. The grain boundary structures in the respective bicrystals were thus analyzed by combination of HREM and static lattice calculation. HRTEM observation revealed that the present grain boundaries have asymmetrical structures with translation along the grain boundary plane. The most stable grain boundary models calculated by static lattice calculation well correspond with the HREM image. It was found that characters of
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grain boundary plane are an important factor to determine grain boundary atomic structures. The behavior of grain boundary sliding was also investigated by high temperature compressive creep test. The creep behavior due to grain boundary sliding was found to depend on the grain boundary structures and atomic density The [0001] tilt grain boundaries in pure alumina contained large open spaces along the boundary plane. The Y-doped boundary in alumina also exhibited a similar core structure, indicating that Y ions segregation did not change the grain boundary structure even at the atomic level. In addition, static lattice calculations showed that Y ions tended to be located around the open spaces at the grain boundary core. Therefore, it is thought that Y ions play a role for decreasing atomic diffusivity at the open grain boundary core even when their concentration is quite small. Based on the results mentioned above, importance of grain boundary atomic structures and characters were quantitatively understood, and an guideline to design ceramic grain boundary were proposed in this study. Less
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