Thin film piezoelectric device and ink jet recording head comprising the same

A process for producing a thin film piezoelectric device comprising (a) a piezoelectric film which is polycrystalline and (b) two electrodes by which the piezoelectric film is sandwiched, wherein the size of crystal grains of the piezoelectric film is 0.4 .mu.m-3 .mu.m and is equal to or less than the thickness of the piezoelectric film, and wherein the piezoelectric film has a thickness of 1 .mu.m-5 .mu.m, said method comprising the steps of

• forming a precursor film of the piezoelectric film on a first electrode,
• a first heating step of heating the electrode on which the precursor film is formed at a temperature of 500 to 700.degree. C. in an oxygen-containing atmosphere to crystallize the precursor film, thereby obtaining a polycrystallized film having crystal grains,
• a second heating step of heating, without cooling the electrode after the first heating step, the electrode on which the polycrystallized film is formed at a temperature of 750 to 1,200.degree. C. in an oxygen-containing atmosphere to control the size of the crystal grains and to form the piezoelectric film wherein the size of crystal grains of the piezoelectric film is 0.4 .mu.m-3 .mu.m and is equal to or less than the thickness of the piezoelectric film, and wherein the piezoelectric film has a thickness of 1 .mu.m-5 .mu.m, and
• providing a second electrode on the piezoelectric film so that the piezoelectric film is sandwiched between the first and second electrodes.