Abstract
The electric field-induced strain in lead-free piezoceramics is generally limited to less than 0.4%, which hinders their practical applications such as actuator. Herein we report a new composition of 0.94Bi0.5Na0.5TiO3-0.06Ba0.85Ca0.15Ti0.9Zr0.1O3-xLi0.06(K0.5Na0.5)0.94NbO3 (BNT-BCZT-xLKNN) ceramics by adding two modifiers (i.e., Li0.06(K0.5Na0.5)0.94NbO3 and Ba0.85Ca0.15Ti0.9Zr0.1O3) featuring with a morphotropic phase boundary (MPB) into the Bi0.5Na0.5TiO3 system. The BNT-BCZT-0.02LKNN shows a high strain of 0.5% as well as a strain-electric field ratio (Smax/Emax) of 625 pm/V, which is one of the best performances compared with reported lead-free piezoceramics. Rietveld refinement and microstructure analysis confirmed the existence of tetragonal (P4bm) and rhombohedral (R3c) phases, and a small part of ferroelectric domains embedded into relaxors according to the PFM, both facilitating the relaxor-to-ferroelectric transformation under an external electric field. As a result, a high strain is obtained in the BNT-BCZT-LKNN system. Our work provides an effective strategy for designing novel lead-free materials with high strain.
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