2002 Fiscal Year Final Research Report Summary
BISMUTH-BASED FERROELECTRICS AND THEIR APPLICATIONS TO LEAD-FREE PIEZOELECTRIC DEVICES
| Project/Area Number |
13555176
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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 | 展開研究 |
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| Research Field |
Inorganic materials/Physical properties
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| Research Institution | FUCULTY OF CIENCE AND TECHNOLOGY, TOKYO UNIVERSITY OF SCIENCE |
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Principal Investigator |
TAKENEKA Tadashi FACULTY OF SCIENCE AND TECHNOLOGY, TOKYO UNIVERSITY OF SCIENCE, PROFESSOR, 理工学部, 教授 (70096709)
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| Co-Investigator(Kenkyū-buntansha) |
NOMURA Takeshi MATERIALS RESEARCH CENTER, TDK CORPORATION, DIRECTOR, 基礎材料研究所, 取締役・所長
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| Project Period (FY) |
2001 – 2002
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| Keywords | PIEZOELECTRICS / ELECTROMECHANICAL COUPLING FACTOR / LEAD-FREE PIEZOELECTRICS / FERROELECTRICS / BISMUTH PEROVSKITES / BISMUTH LAYER-STRUCTURED FERROELECTRIS / RESIBATOR / MECHANICAL QUALIY, FACTOR |
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| Research Abstract |
Recently, lead-free piezoelectric materials have been attracting attention as new materials in place of PZT materials for environments. Among of many lead-free piezoelectric materials, bismuth layer-structured ferroelectric (BLSF) ceramics will be a superior candidate because of their low dielectric constant ε s, high Curie temperature, T c, and large anisotropy in electromechanical coupling factors k t/k p or k33/k31
In this research, one of BLSF, Srx-_1Bi_4-_xTi2-_xTaxO9 (x=1〜2) [SBTT2] and Bi_3-_xLax TiTaO9 [BLTT2] ceramics are studied on their ferroelectric and piezoelectric properties which are applied to lead-free piezoelectric devices. Also new lead-free piezoelectric devices were designed and prepared to evaluate the piezoelectric properties. (1) The SBTT2 and BLTT2 ceramic shows high mechanical quality factors, Qm under the proper poling conditions with high temperatures and high electric field. (2) BLSF ceramics with high Curie temperatures and large coercive field have essentially high Qm which are able to be obtained by the high temperature poling process of 250〜300 ℃. (3) A resonator which is one of lead-free piezoelectric devices was designed and prepared by using of SBTT2 ceramics. The characteristics of the device were evaluated and compared with those of the lead-based devices. (4) The overall results in this research show that SBTT2 and BLTT2 ceramics seem to superior candidate materials for lead-free high functional piezoelectric devices of key components for mobile communication in next generation
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