| 摘要 |
A compact and wide band surface acoustic wave device for intermediate-frequency is disclosed. A piezoelectric substrate for use in a surface acoustic wave device having high electromechanical coupling factor and low SAW velocity is also disclosed. The surface acoustic wave device is constituted of a piezoelectric substrate 1 and inter-digital electrodes 2, 2 formed on the piezoelectric substrate 1. The piezoelectric substrate 1 has a crystal structure of Ca3Ga2Ge4O14 and is represented by the chemical formula, Sr3NbGa3Si2O14. A cut angle of the piezoelectric substrate 1 cut out of the single crystal and a direction of propagation of surface acoustic waves on the piezoelectric substrate represented in terms of Euler's angles (phi, theta, psi) are found in one of a first area represented by -5°<=phi<=15°, 0°<=theta<=180°, and -50°<=psi<=50° and a second area represented by 15°<=phi<=30°, 0°<=theta<=180°, and -40°<=psi<=40°.
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