Patent ID: 7183694

Claim:
A piezoelectric/electrostrictive device comprising: a ceramic substrate having a frame-like thick portion, a thin diaphragm portion disposed integrally on an end surface of the thick portion in such a manner as to cover the thick portion, and a cavity formed by the thick portion and the thin diaphragm portion in such a manner as to communicate with the outside; and a piezoelectric/electrostrictive element having a layered structure fixed to an outer surface of the thin diaphragm portion of the ceramic substrate and including a lower electrode, a piezoelectric/electrostrictive film, and an upper electrode, the thin diaphragm portion of the ceramic substrate being vibrated in conjunction with driving of the piezoelectric/electrostrictive element, while changing an internal volume of the cavity, wherein the thin diaphragm portion has an outward protruding arch shape that is one of a rectangular shape, an elongated circular shape, and an elliptical shape having an aspect ratio of 1.5 or more, and in the piezoelectric/electrostrictive element, there remains a tensile stress of 50 MPa to 200 MPa parallel to a fixed surface of the piezoelectric/electrostrictive element with respect to the thin diaphragm portion.