Growth of Piezoelectric <Li_2> <B_4> <O_7> Single Crystal and its Applications to Ultra High Frequency Surface Acoustic Wave Devices

压电<Li_2><B_4><O_7>单晶的生长及其在超高频声表面波器件中的应用

• 批准号: 60460122
• 负责人: SHIOSAKI Tadashi
• 金额: $ 4.48万
• 依托单位: Kyoto University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (B)
• 财政年份: 1985
• 资助国家: 日本
• 起止时间: 1985 至 1986
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-60460122/
• 关键词: Lithium Tetraborate; Surface Acoustic Wave; Bulk Acoustic Wave; Temperature Coefficient of Delay; Coupling; 表面波共振子; 機械的品質係数; 結合係数

Lithium tetraborate ( <Li_2> <B_4> <O_7> ) has attracted much attention as a promising candidate for the new surface acoustic wave (SAW) and also as bulk acoustic wave (BAW) materials because of its very low temperature coefficient of frequency (TCF) and high coupling. The object of this project is growth of good quality <Li_2> <B_4> <O_7> (LBO) crystal and its applications. The abstract is as follows:1. Transparent, core-free and good quality single crystals of <Li_2> <B_4> <O_7> , up to 23mm in diameter and 80mm in length, have been successfully grown from a congruent melt at rotation rates around 40rpm and growth rate of 1.7mm/h by an automatic diameter control (ADC) of the Czochralski method. It has been pointed out that the growth rate will become higher by making the rotation rate higher and the temperature profile steeper at the solid-melt boundary.2. All the dielectric, elastic and piezoelectric constants and their first- and second-order temperature coefficients have been determined in detail by measuring resonant and antiresonant frequencies.3. The existance of orientations of lithium tetraborate with zero temperature coefficient of delay or frequency have been predicted on the basis of the material constants determined by the present authors, and confirmed experimentally for the Rayleigh and leaky SAW and BAW. There are useful substrate orientations for SAW devices with zero TCD around (0゜,78゜,90゜), (0゜,90゜,78゜) and (45゜,90゜,90゜), where <k_s^2> is approximately 0.8-1%. However, among these substrates, the (45゜,90゜,90゜) is the most suitable substrate, Further, it has been confirmed that the temperature compensated cuts for rotated Y-cut bulk wave devices exist at <theta> of 32゜ for the quasi-longitudinal mode and <theta> of 53゜ for the quasi-shear mode.4. The resonater with Q of 3400 have been successfully fabricated.

四硼酸锂（<Li_2> <B_4> <O_7>）由于其极低的温度频率系数（TCF）和高耦合性，作为新型表面声波（SAW）和体声波（BAW）材料备受关注。本课题的目的是生长优质的<Li_2> <B_4> <O_7> (LBO)晶体及其应用。论文摘要如下：1。利用Czochralski法的自动直径控制（ADC），以40rpm的转速和1.7mm/h的生长速度，成功地在等量熔体中生长出了透明、无芯、质量良好的<Li_2> <B_4> <O_7>的单晶，单晶直径可达23mm，长80mm。在固-熔边界处，转速越高，温度曲线越陡，生长速率越高。通过测量谐振频率和反谐振频率，详细测定了介质常数、弹性常数和压电常数及其一阶和二阶温度系数。本文在确定材料常数的基础上，预测了四硼酸锂存在温度延迟系数为零或频率为零的取向，并对瑞利型和漏态SAW和BAW进行了实验验证。对于TCD为零的SAW器件，在（0、78、90）、（0、90、78）和（45、90、90）周围有有用的衬底方向，其中<k_s^2>约为0.8-1%。然而，在这些衬底中，（45,90,90）是最合适的衬底。此外，已经证实旋转y形切割体波器件的温度补偿切割存在于准纵向模式下< 32的theta>和准剪切模式下< 53的theta>。成功地制作了Q值为3400的谐振腔。

项目成果

塩崎忠: to be published in Proceedings of IEEE 1986 International Symposium on the Applications of Ferroelectrics,IEEE New York,(June,9-11,1986;Bethlehem,Pennsylvania). (1987)

Tadashi Shiozaki：发表于 IEEE 1986 国际铁电体应用研讨会论文集，IEEE 纽约，（1986 年 6 月 9 日至 11 日；宾夕法尼亚州伯利恒）（1987 年）。

Masatoshi Adachi: "Temperature Compensated Piezoelectric Lithium Tetraborate Crystal for High Frequency Surface Acoustic Wave and Bulk Wave Device Applications" 1985 IEEE Ultrasonic Symposium Proceedings (Oct. 16-18, 1985, San Francisco, California). 85CH

Masatoshi Adachi：“用于高频表面声波和体波器件应用的温度补偿压电四硼酸锂晶体”1985 IEEE 超声波研讨会论文集（1985 年 10 月 16-18 日，加利福尼亚州旧金山）。

Masatoshi Adachi: "Crystal Growth of Lithium Tetraborate ( <Li_2> <B_4> <O_7> )" Proceedings of the 5th Meeting on Ferroelectric Materials and Their Applications Kyoto 1985, Japanese Journal of Applied Physics, Suppl. 24-3. 24. 72-75 (1985)

Masatoshi Adachi：“四硼酸锂（<Li_2> <B_4> <O_7>）的晶体生长”第五届铁电材料及其应用会议记录，京都 1985 年，日本应用物理学杂志，增刊。

安達正利: 1985 IEEE Ultrasonics Symposium Proceedings,85CH2209-5(Oct.16-18,1985,San Francisco,California). 1. 228-232 (1986)

Masatoshi Adachi：1985 年 IEEE 超声波研讨会论文集，85CH2209-5（1985 年 10 月 16-18 日，加利福尼亚州旧金山）1. 228-232 (1986)。

Tadashi Shiosaki: "Elastic, Piezoelectric, Acousto-Optic and Electro-Optic Properties of <Li_2> <B_4> <O_7> " Proceedings of the 5th Symposium on Ultrasonic Electronics, Tokyo 1984 Japanese Journal of Applied Physics, Suppl. 24-1. 24. 25-27 (1985)

Tadashi Shiosaki：“<Li_2> <B_4> <O_7> 的弹性、压电、声光和电光特性”，第五届超声波电子学研讨会论文集，东京 1984 年 日本应用物理学杂志，增刊。