A piezoelectric layer made of potassium sodium niobate which is a perovskite type compound represented by the formula ABO3, wherein, in the Raman spectroscopy measurement of the piezoelectric layer which is performed while the piezoelectric layer is rotated in the in-plane direction, the measured intensity of the lattice vibration region of the perovskite type compound in the Raman spectrum obtained in polarized Raman spectroscopy measurement (yx) has a periodicity of approximately 90°, wherein, the polarized Raman spectroscopy measurement (yx) is performed while the piezoelectric layer is rotated in the in-plane direction and Raman scattering light is polarized in a direction perpendicular to that of the incident light.
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