PIEZOELECTRIC COMPOSITION AND METHOD FOR PRODUCING SAME, PIEZOELECTRIC ELEMENT/NON-LEAD PIEZOELECTRIC ELEMENT AND METHOD FOR PRODUCING SAME, ULTRASONIC PROBE AND DIAGNOSTIC IMAGING DEVICE

The present invention is a piezoelectric composition and a piezoelectric element using the piezoelectric composition, the composition being characterized by: having a Perovskite structure represented by general formula ABO3; being represented by composition formula x(Bi0.5K0.5)TiO3-yBi(Mg0.5Ti0.5)O3-zBiFeO3, x+y+z=1 in the composition formula above; and in a triangular coordinate using x, y and z in the composition formula above, having a composition represented by a region which is surrounded by a pentagon ABCDE with apexes of point A (1, 0, 0), point B (0.7, 0.3, 0), point C (0.1, 0.3, 0.6), point D (0.1, 0.1, 0.8) and point E (0.2, 0, 0.8) and which does not include the line segment AE that connects point A (1, 0, 0) and point E (0.2, 0, 0.8).