Process for producing a piezoelectric element using a first SOL and a second SOL having a lead content greater than the first SOL

A process for producing a piezoelectric element comprising a piezoelectric film, an upper electrode and a lower electrode with the piezoelectric film held therebetween, said process comprising:

• a) applying, at least once, a first sol for use in forming the piezoelectric film on a substrate having the lower electrode formed thereon to form a lower film;
• b) drying the lower film by subjecting to heat treatment at a first temperature;
• c) pyrolyzing the lower film by subjecting to heat treatment at a second temperature which is higher than the first temperature;
• d) applying a second sol having a greater lead content than the first sol to form an upper film;
• e) drying the upper film by subjecting to heat treatment at the first temperature;
• f) pyrolyzing the upper film by subjecting to heat treatment at the second temperature;
• g) crystallizing the lower and upper films by subjecting to heat treatment at a third temperature which is higher than the second temperature after step f);
• h) performing a cycle comprising steps a) to f);
• and
• i) crystallizing the films by subjecting to heat treatment at a fourth temperature which is higher than the third temperature, after step h);
• wherein a cycle comprising steps a) to g) is performed at least once.