The invention claimed is:
1. A piezoelectric element comprising a lower electrode, a piezoelectric layer made from potassium-sodium niobate, which is a perovskite type compound represented by a general formula ABO 3 , and an upper electrode,
wherein the piezoelectric layer is present between the lower electrode and the upper electrode, and
the piezoelectric layer has a characteristic such that the intensity of a diffraction peak, where the angle of 2θ is within the range of 21.1°≦2θ23.4° in the X-ray diffraction pattern (2θ/θ), divided by the intensity of a diffraction peak, where the angle of 2θ is within the range of 30.1°≦2θ≦33.3°, is 0.04 or less.
2. The piezoelectric element according to claim 1 , wherein the lower electrode is made from an electrically conductive substance oriented in the {001} face orientation and is in contact with the piezoelectric layer.
3. The piezoelectric element according to claim 2 , wherein the electrically conductive substance is platinum.
4. A piezoelectric actuator comprising the piezoelectric element according to claim 1 .
5. A piezoelectric sensor comprising the piezoelectric element according to claim 1 .
6. A hard disk drive comprising the piezoelectric actuator according to claim 4 .
7. An ink-jet printer device comprising the piezoelectric actuator according to claim 4 .