1996 Fiscal Year Final Research Report Summary
Pase decomposition in zirconia ceramics
| Project/Area Number |
07455277
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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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 |
SAKUMA Taketo Dept.of Mater.Sci., Fac.of Eng., Professor, 大学院・工学系研究科, 教授 (50005500)
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| Project Period (FY) |
1995 – 1996
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| Keywords | zirconia / phase transition / oxygen vacancies / phase diagram / mechanical alloying |
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| Research Abstract |
The cubic-tetragonal (c-t) two-phase equilibria in ZrO_2-CeO_2 and ZrO_2-R_2O_3 (R : rare earths) systems and related phenomena were examined. The results obtained are summarized as follows.
(1) The c-t transformation in near-stoichiometric ZrO_2-CeO_2 is regarded as a second-order phase transition.
(2) In nonstoichiometric (Zr, Ce) O_2-x, -oxygen ions are regularly displaced in the <111> direction in a cubic form. A variety of forbidden reflections appear in the diffraction patterns by the displacement in cubic fluorite structure.
(3) The c-t transformation in nonstoichiometric (Zr, Ce) O_2-x has a nature of first-order phase transition.
(4) The c-t two-phase field in ZrO_2-R_2O_3 systems is dependent on the type of R^<3+> ions. Thermodynamic assessment is successful to describe the observed two-phase fields in vaious ZrO_2-R_2O_3 systems on the assumption that the c-t transformation is of a second-order type.
(5) It is possible to obtain ZrO_2-ZrN solid solutions by mechanical alloyins,
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