Mechanical stability of (Li,Na,K)NbO3-based multilayered piezoceramics with Ag/Pd inner electrodes

Abstract

Lead-free (Li,Na,K)NbO3-based multilayered piezoceramics with Ag0.9Pd0.1 inner electrodes were prepared, and their large-signal piezoelectric properties under combined electrical and mechanical loadings were characterized at room temperature. The piezoelectric constant d33∗(=SMax/EMax) of the multilayer was 96 pm/V with an applied unipolar field of 5 kV/mm under zero stress. More importantly, a favorable stress stability of d33∗ was observed, with a slight variation ≤8% of SMax, when the uniaxial stress was increased from −5 to −80 MPa. Further investigations of temperature-dependent x-ray diffraction, permittivity, and an energy-dispersive x-ray spectrometer revealed that the mechanical stability of d33∗ was due to a shift in phase transition temperature caused by a solid solution of the Ag inner electrode to the A-site of (Li,Na,K)NbO3 piezoceramics.