| Project/Area Number |
10555111
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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 |
電子デバイス・機器工学
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| Research Institution | Tohoku Institute of Technology (1999)
Tohoku University (1998) |
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Principal Investigator |
YAMANOUCHI Kazuhiko Department of Electronics, Tohoku Institute of Technology Professor, 工学部, 教授 (00006230)
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| Co-Investigator(Kenkyū-buntansha) |
HIROYUKI Odagawa Research Institute of Electrical Communication, Tohoku University, Research Associate, 電気通信研究所, 助手 (00250845)
TSUYOSHI Takano Department of Communication, Professor, 工学部, 教授 (50085411)
目黒 敏靖 東北大学, 電気通信研究所, 助手 (50182150)
長 康雄 東北大学, 電気通信研究所, 助教授 (40179966)
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| Project Period (FY) |
1998 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥13,100,000 (Direct Cost: ¥13,100,000)
Fiscal Year 1999: ¥2,400,000 (Direct Cost: ¥2,400,000)
Fiscal Year 1998: ¥10,700,000 (Direct Cost: ¥10,700,000)
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| Keywords | Surface Acoustic Wave / KNbO_3 single crystal / Zero TCF Substrate / Elastic Convolver / Piezoelectric Single Crystals / Wide Band Filters / Spread Spectrum Communication / Mobile Communication / KNbO3単結晶 / 零温度係数基板 / 超高結合材料 / 弾性表面波コンボルバ / KNbO_3 / 圧電薄膜 |
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| Research Abstract |
Surface Acoustic Waves (SAW) are applied for the key devices of the future mobile communication as the high performance, light weight and small size, and mass production devices. The properties of SAW devices mainly depend on the choice of piezoelectric substrate materials. The important properties required for SAW substrates are large electromechanical coupling coefficient (k^2) and small temperature coefficient of frequency (TCF). Especially, super high coupling substrates are very important for fabricating the wideband SAW filters with small insertion loss. KNbO_3 single crystal has extremely large electromechanical coupling coefficient (K_2=53%) and zero TCF around a room temperature [1]. Also, single crystal growth technologies with a large size are very important for device applications.
In this research, we obtained the following results :
(1) The KNbO_3 single crystal growth with a large size are investigated. The Top Seeded Solution Growth Techniques (TSSG) and the large size of
… More
crucible of 60mm φ Platinum are applied in order to obtain a large size of KNbO_3 single crystal. The results show the 50x50x15mm^3 single crystals are obtained. Also, the poling techniques of KNbO_3 crystal are investigated by using the nonlinear scanning dielectric microscope and the poling direction is determined.
(2) The results of the experimental SAW properties of the above KNbO_3 single crystal substrates agree with the theoretical ones. Also the KNbO_3 substrates showed experimentally the zero temperature coefficients of frequency (TCF) around 20℃. We are now trying to apply for zero TCF and wide band SAW filters.
(3) We determined the nonlinear piezoelectric constants of KNbO_3. Also, the high efficient (+25dB higher than that of LiNbO_3) SAW elastic convolvers using KNbO_3 crystals than LiNbO_3 crystals are obtained.
(4) The theoretical SAW propagation characteristics with the k^2 of about100% are analyzed and the physical phenomena of those are discussed.
The above investigating results are very useful for the information technology of the next generation, especially for the mobile communication technology. Less
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