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 d(33)*(= S-Max/E-Max) 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 d(33)* was observed, with a slight variation <= 8 of S-Max, 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 d(33)* 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.
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