1992 Fiscal Year Final Research Report Summary
High Rate Growth of Large Diameter and High Quality Li_2B_4O_7 Piezoelectric Crystals and Practical Research on SAW Devices
| Project/Area Number |
03555060
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| Research Category |
Grant-in-Aid for Developmental Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
電子材料工学
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
SHIOSAKI Tadashi Kyoto Univ.DEPT. of Electronics Assist Prof., 工学部, 助教授 (80026153)
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| Co-Investigator(Kenkyū-buntansha) |
FUJIMURA Sigeto Nippon Mining Co. Ltd., Dept. of Q&E, Researcher, O&E事業部, 研究員
MIWA Kazuo Nipoon Mining Co., Ltd., Dept. of Q&E, Researcher, O&E事業部, 研究員
SHIMIZI Masaru Kyoto Univ.Dept. of Electronics Research, 工学部, 助手 (30154305)
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| Project Period (FY) |
1991 – 1992
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| Keywords | Single crystal / Li_2B_4O_7 / Czochralski method / Zero TCD / Surface acoustic wave / Photo refractive effect / LiNbO_3 / BaTiO_3 |
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| Research Abstract |
Transparent, core free and high quality single crystals of Li_2B_4O_7 were successfully grown from a congruent melt at rotation rate of 38.5rpm and growth rate of 3mm/h by the ADC(Automatic Diameter Con-trol) controlled Czochralski method. New Crystal growth methods adjusting the relationship between the rf-output power and the crystal rotation rate during the growth were proposed in order to improve the relatively low growth rate of Li_2B_4O_7. All the dielectric, elastic and piezoelectric constants and their first and second-order temperature coefficients have been measured.
The existence of an orientation with zero TCD(Temperature Coefficient of Delay) was predicted by a computer analysis and confirmed experimentally for the Raleigh and leaky SAW and BAW. There are useful substrate orientations for SAW devices with zero TCD around(0ﾟ,78ﾟ,90ﾟ), where K_S^2 is approximately 1%. There is also a useful substrate orientation for the leaky SAW devices with a small TCD and a large coupling of 1.8% around(0ﾟ,75ﾟ,75ﾟ). 900MHz SAW resonator filters were fabricated on Li_2B_4O_7 crystals.
Using the same Czochralski technique, LiNbO_3 and BaTiO_3 single crystals were successfully grown. The Photorefractive effect in these crystals were investigated for applications to phase conjugate genarator and optical associative memory.
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