| Budget Amount *help |
¥7,400,000 (Direct Cost: ¥7,400,000)
Fiscal Year 1996: ¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1995: ¥5,400,000 (Direct Cost: ¥5,400,000)
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| Research Abstract |
In this study, we have developed a new method of determining the acoustical physical constants associated with piezoelectric crystals, using two systems of line-focus-beam acoustic microscopy and bulk ultrasonic spectroscopy, and have determined precisely all the independent constants of LiNbO_3 and LiTaO_3 single crystals, including the density.
1. In order to improve reliability and reproducibility of the two systems, the measurement environment of temperature has been stabilized and a laser interferometer has been introduced to measure the absolute distance. Absolute accuracy of better than (]SY.+-。[)0.01% in velocity has been achieved.
2. Many crystalline plane specimens of LiNbO_3 and LiTaO_3 with optically polished surfaces and excellent parallelism of front and back surfaces have been prepared from one ingot for each crystal.
3. A new method of determining the acoustical physical constants, viz., stiffness, piezoelectric, and dielectric constants, has been developed using the two systems for velocity measurements.
4. The acoustical physical constants of LiNbO_3 and LiTaO_3 have been determined, which provide five significant digits for bulk and surface acoustic wave velocities.
5. The elastic constants for multi-domain LiTaO_3 crystals have been also determined, for the first time, and have been compared with those for single-domain LiTaO_3 crystals. It has been shown that the poling operation to introduce piezoelectricity is responsible for the differences of elastic properties between single-and multi-domain crystals.
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