Abstract: Further improvements in circuit-element performance of surface-acoustic wave devices are anticipated by being able to produce a diamond substrate on which is formed a Li(NbxTa1−x)O3 (wherein 0≦x≦1) thin film whose c-axis orientation is favorable and whose piezoelectric characteristics are satisfactory. A diamond substrate on which a highly c-axis oriented, piezoelectrically satisfactory Li(NbxTa1−x)O3 (wherein 0≦x≦1) thin film is formed can be obtained by using a laser ablation technique to form a Li(NbxTa1−x)O3 (wherein 0≦x≦1) thin film onto a (110)-oriented gas-phase synthesized polycrystalline diamond substrate, that is superficially mirror-surface processed and superficially covered with an amorphous layer. By utilizing a diamond substrate on which a piezoelectric-substance thin film is formed, surface-acoustic wave devices having high propagation speeds can be offered.

Abstract: Provided are a substrate for a surface-acoustic-wave device and a surface-acoustic-wave device, in which an intermediate layer for controlling crystal characteristics of a piezoelectric layer does not easily separate from a diamond layer.