| 摘要 |
PROBLEM TO BE SOLVED: To provide the surface acoustic wave provided with a langasite single crystal substrate having an apex temperature around rom temperature and indicating an excellent temperature characteristic. SOLUTION: Let a segmented angle of a langasite and a propagation direction of a surface acoustic wave be (ϕ,θ,ψ) in the Euler angle representation, and an electrode has a normalized film thickness h/λthat satisfies expressions 8.52×10-7×(TP-TPO)3+4.15×10-4×(TP-TPO)2+1.01×10-3×(TP-TPO)+6.57×10-3>=h/λand h/λ>=-5.58×10-6×(TP-TPO)3+2.05×10-4×(TP-TPO)2+1.22×10-3×(TP- TPO)+4.00×10-3, where TP is a desired apex temperature and TPO is an apex temperature of a surface acoustic wave propagated along the surface of a substrate with a normalized film thickness h/λ=0 atϕ=-5 to 5 degrees.θ=125-150 degrees, andψ=20-30 degrees.
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