1998 Fiscal Year Final Research Report Summary
3C*6H Polytypic Transition Mechanism of SiC and Factors Affecting on Phase Transformation
| Project/Area Number |
09640663
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Inorganic chemistry
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| Research Institution | Nagoya University |
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Principal Investigator |
SEO Wonseon Grad.School of Eng., Nagoya Univ., Assistant Professor, 大学院・工学研究科, 助手 (30242829)
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| Co-Investigator(Kenkyū-buntansha) |
SUZUKI Yutaka Grad.School of Eng., Nagoya Univ., Assistant Professor, 大学院・工学研究科, 助手 (60023214)
KUWABARA Katsumi Grad.School of Eng., Nagoya Univ., Assistant Professor, 大学院・工学研究科, 講師 (40023262)
KOUMOTO Kunihito Grad.School of Eng., Nagoya Univ., Professor, 大学院・工学研究科, 教授 (30133094)
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| Project Period (FY) |
1997 – 1998
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| Keywords | Silicon Carbide / Phase Transformation / Stacking Faults / Mechanism / Grain Growth / Carbothermal Reduction / Dislocation |
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| Research Abstract |
Carefully controlled experiments were carried out to clarify phase transformation mechanism. The effects of stacking fault, the impurity, and morphology on the phase transformation were also investigated. The following conclusions can be drown from the present study.
1)Previous phase transformation mechanism
Though polytypic transformations in SiC have been studied by many researchers, the transformation mechanisms are still controversial because there is no indisputable evidence for the proposed mechanisms. However, recent development of HREM technique and single crystal growth technique give us a chance to clarify the polytypic transformation mechanism for SiC.
2) Factors affecting on the phase transformation
The impurity, stacking faults, and grain morphology are closely related to the phase transformation of SiC.The 3C*4H transformation occur directly for the starting powder with high stacking fault density, while 3C*6H transformation occur for the starting powder with low stacking fault density. It is considered that stacking faults is acted as a seed for 3C*4H phase transformation.
3)New phase transformation mechanism
From the observation of HREM in partially transformed SiC single crystal, we confirmed that polytypic transformation is caused by the slip of separated successive 2 layers and their repetition. Transformation is accomplished by slip due to only dislocation without forming the specialized habit plane and glide plane.
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