DIELECTRIC ELEMENT BASE MATERIAL, METHOD FOR PRODUCING SAME, AND PIEZOELECTRIC ELEMENT USING SAID DIELECTRIC ELEMENT BASE MATERIAL

摘要

A dielectric element substrate includes a board, a diffusion layer, a first isolation layer, and a lower electrode layer. The diffusion layer is provided on the board. The first isolation layer is provided on and unitarily with the diffusion layer. The lower electrode layer is provided on the first isolation layer at an opposite side with respect to the diffusion layer of, and is isolated from the diffusion layer by the first isolation layer. The diffusion layer is formed by allowing a first metal element and a second metal element to diffuse from the board to the same composition material as that of the first isolation layer. The first isolation layer is free from the first and second metal elements. A coefficient of thermal expansion of the diffusion layer decreases monotonously from the board to the first isolation layer.