Method of producing a piezoelectric/electrostrictive film element

A method of producing a piezoelectric/electrostrictive film element comprising:

• a zirconia substrate having at least one window, and a diaphragm portion formed as an integral part of said zirconia substrate and closing each of said at least one window;
• and a film-like piezoelectric/electrostrictive unit including a lower electrode, a piezoelectric/electrostrictive layer and an upper electrode, which are formed in the order of description on an outer surface of said diaphragm portion by a film-forming process, said method comprising the steps of:
• preparing said zirconia substrate which has been sintered and in which at least said diaphragm portion contains alumina in an amount of 1.1-5.0 parts by weight;
• forming, by a film-forming process, said lower electrode on said outer surface of said diaphragm portion, and said piezoelectric/electrostrictive layer on said lower electrode by using a piezoelectric/electrostrictive material which contains magnesia or a component which gives magnesia, in an independent form or in a compound form;
• and
• firing said piezoelectric/electrostrictive layer, so as to deposit particles consisting principally of a compound of alumina and magnesia at least on an interface between said diaphragm portion and said lower electrode, said interface being located right under said piezoelectric/ electrostrictive layer.