| 摘要 |
PROBLEM TO BE SOLVED: To provide a surface acoustic wave device, for an intermediate frequency, which is small and whose passband is wide and to provide a piezoelectric substrate, for the surface acoustic wave device, which has a high coupling coefficient and which has a low SAW speed. SOLUTION: The surface acoustic wave device is provided with the piezoelectric substrate 1 and a crossed finger-shaped electrode 2, which is formed on the piezoelectric substrate. The substrate 1 has a Ca3Ga2Ge4O14-type crystal structure, and it is expressed by a chemical formula of Sr3NbGa3Si2O14. If the cutting angle from a single crystal and the propagation direction of surface acoustic waves are expressed by Euler angle representation as (ϕ,θ,ψ) with reference toϕ,θandψ, the structure exists in a first region whereϕis -5 to 15 deg.,θis 0 to 180 deg. andψis -50 to 50 deg. or in a second region whereϕis 15 to 30 deg.,θis 0 to 180 deg. andψis -40 to 40 deg..
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