1999 Fiscal Year Final Research Report Summary
SYNTHESIS OF NANOSTRUCTURED TRANSPARENT BaTiO_3 CERAMICS WITH NOVEL ELECTRONIC AND OPTICAL PROPERTIES
| Project/Area Number |
09305043
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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 |
Inorganic materials/Physical properties
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| Research Institution | UNIVERSITY OF TOKYO |
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Principal Investigator |
KUWABARA Makoto UNIVERSITY OF TOKYO, GRADUATE SCHOOL OF ENGINEERING, PROFESSOR, 大学院・工学系研究科, 教授 (40039136)
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| Co-Investigator(Kenkyū-buntansha) |
MATSUDA Hirofumi UNIVERSITY OF TOKYO, GRADUATE SCHOOL OF ENGINEERING, RESEARCH ASSOCIATE, 大学院・工学系研究科, 助手 (00282690)
MIYAZAWA Kun'ichi UNIVERSITY OF TOKYO, GRADUATE SCHOOL OF ENGINEERING, LECTURER, 大学院・工学系研究科, 講師 (60182010)
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| Project Period (FY) |
1997 – 1999
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| Keywords | Barium titanate / Sol-gel method / Transparent crystalline gels / Translucent ceramics / Ferroelectric property / Optical property / Pore size distribution / Grain size effect |
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| Research Abstract |
The objective of this study is to establish a procedure nanostructured transparent (or translucent) barium titanate ceramics with novel electronic and optical properties by high concentration sol-gel processing, which was individually developed by us, to introduce an important innovation in the field of electroceramics.
The obtained results are summarized as follows :
1) Synthesis of transparent BaTiO_3 monolithic gels : We succeeded in synthesizing transparent BaTiO_3 monolithic gels from highly concentrated Ba, Ti alkoxides solution (1.0 mol/L) by hydrolyzing with water vapor at 0℃, followed by aging for several days at 30-500℃. The gel's properties, including the degree of crystallization and pore structure, were characterized quantitatively on the basis of the influenced of the amount of hydrolysis water and the hydrolysis temperature upon the properties.
2) Clarification of the creation mechanism of BaTiO_3 nanocryst allites : It has been found that nanocryst alline BaTiO_3 particles
… More
are formed directly from the precursor solution when a sufficient amount of hydrolysis water is used.
3) Analysis of the pore structure and optical properties of transparent gels : Using an N_2 absorption-desorption porosimeter the pore structure of transparent BaTiO_3 gels has been characterized to have a narrow distribution of pores in the range of 3 to 10nm. The optical absorption edge of the cryst alline BaTiO_3 particles was found to be larger than that of bulk Batio_3 crystal due to probably the size effect.
4) Preparation of translucent BaTiO_3 ceramics : We succeeded in producing translucent BaTiO_3 ceramics by sintering transparent gels with a specific pore structure at 1100℃ in an O_2 at mosphere, which gels showed an unusual densification behavior that is characterized by a significant densification starting at a low temperature below 500℃.
5) Characterization of dielectric and optical properties of translucent BaTiO_3 ceramics : The dielectric properties of translucent BaTiO_3 ceramics with sub-micrometer grain sizes have been measured. The translucent ceramics have been found to exhibit ferroelectric properties, which was demonstrated by a distinct dielectric peak at the Curie temperature and a well-defined hysteresis loop at room temperature. A distinct electro-optic effect of light scattering was observed for a large grain-sized translucent BaTiO_3 ceramic, though, unfortunately, novel optical properties due to the size effect was not observed for the present translucent BaTiO_3 ceramics because of their large grain sizes. Less
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