Piezoelectric thin-film element, piezoelectric sensor and vibration generator
Abstract:
A piezoelectric thin-film element includes a substrate, a lower electrode layer formed on the substrate, a piezoelectric thin-film layer that is formed on the lower electrode layer and includes potassium sodium niobate having a perovskite structure represented by the composition formula of (K1-xNax)NbO3 (0.4≦x≦0.7), and an upper electrode layer formed on the piezoelectric thin-film layer. The piezoelectric thin-film layer is formed such that a value of (Ec−+Ec+)/2 is not less than 10.8 kV/cm and a value of (Pr−+Pr+)/2 is not more than −2.4 μC/cm2 where Ec− and Ec+ are intersection points of a polarization-electric field hysteresis loop and the x-axis indicating an electric field and Pr− and Pr+ are intersection points of the polarization-electric field hysteresis loop and the y-axis indicating polarization.
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