| abstract |
A piezoelectric element includes a substrate, and a lower electrode layer, a piezoelectric layer, and an upper electrode layer sequentially formed on the substrate. The substrate has a linear thermal expansion coefficient higher than that of the piezoelectric layer, and the piezoelectric layer includes a polycrystalline body having an in-plane stress in a compressive direction. Thus, the piezoelectric element realizes the piezoelectric layer having a high orientation in a polarization axis direction, high proportionality of a displacement amount with respect to an applied voltage, and a large absolute value of the displacement amount. |