Patent ID: 8143762

Claim:
An elastic wave device comprising: a piezoelectric body including a LiNbO 3 substrate; a first dielectric layer including a SiO 2 layer located on the piezoelectric body; a second dielectric layer located on the first dielectric layer and having an acoustic velocity higher than that of the first dielectric layer; and an IDT electrode disposed at an interface between the piezoelectric body and the first dielectric layer, which includes a multilayer structure in which a first electrode film including at least one layer including Pt or a Pt-based alloy and a second electrode film including Al or an Al-based alloy are laminated; wherein φ and θ of Euler angles (φ, θ, ψ) of the LiNbO 3 substrate are in a range of φ=0±about 2° and the range of about 80°≦θ≦about 130°, respectively; and the elastic wave device uses an elastic wave the principal component of which is an SH wave; and ψ is in a range of about 5°≦ψ≦about 30°, and where a wavelength of the elastic wave is λ and a thickness of the first electrode film is h, a normalized thickness h/λ and ψ satisfy the following expression: h/λ× 100≦about 0.0019×ψ2+about 0.0115×ψ+about 3.0.