| abstract |
A piezoelectric thin film which has good properties, for example, a high dielectric constant and a high piezoelectric strain constant is disclosed. A method for producing a piezoelectric film, which causes no crack during annealing, is also disclosed. The piezoelectric thin film has a thickness in the range of from 0.5 to 20 µm, comprises crystal grains having an average grain diameter of 0.005 to 0.2 µm, and is free from any multilayer structure in its cross section. The process for producing a piezoelectric thin film comprises that steps of: coating a substrate with a sol composition comprising a sol, of a metal component for constituting a piezoelectric film, and a polymer compound and then drying the coating to form a film; pre-sintering the film to form a porous thin film of gel comprising an amorphous metal oxide; pre-annealing the porous thin film of gel to bring the film to a film formed of a crystalline metal oxide; repeating the above steps at least once to form a laminated film formed of a crystalline metal oxide; and annealing the laminated film to grow crystal grains of perovskite type in the film into a larger size. |