FERROELECTRIC OXIDE AND METHOD FOR PRODUCING THE SAME, PIEZO ELECTRIC CRYSTAL AND PIEZOELECTRIC ELEMENT

摘要

PROBLEM TO BE SOLVED: To provide a ferroelectric oxide excellent in piezoelectric performance.

SOLUTION: In a ferroelectric oxide having the composition represented by the general formula (a1): ABO3(a1) which has the crystal symmetry of a specific structure, composing elements are determined by selecting an A site element A having an ionic radius and an ionic valence which can serve as the A site element and a B site element B having an ionic radius and an ionic valence which can serve as the B site element. The composition is determined so that the Born effective charge of Bi element when an electric field is applied to the ferroelectric oxide having the crystal symmetry of a specific structure in the direction of spontaneous polarization to cause it to be displaced in the direction of spontaneous polarization is larger than the Born effective charge of Bi element of BiFeO3of the same specific structure. The ferroelectric oxide of this composition is produced. In the formula (a1), A is one or more A site elements essentially comprising Bi; B is one or more B site elements; and O is oxygen.

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