1. (a) Room-temperature XRD patterns of the various unpoled KNN ceramics and (b) enlarged parts in (a)

2. Temperature dependence of dielectric permittivity ε' of two representative unpoled KNLNST ceramics, prepared by conventional sintering and two-step sintering, respectively. Inset is partially enlarged curves of dielectric temperature peak of the phase transition from orthorhombic to tetragonal phase

3. Typical SEM images of domain patterns observed in the two unpoled representative KNLNST ceramics

4. (a) Typical SEM image of microstructure and domain pattern of a poled KNLNST-CS ceramic, (b) a partially enlarged image in (a)

5. Typical SEM images of microstructure and domain patterns observed in a poled KNLNST-TSS ceramic.

Table 1. Physical property of KNLNST ceramics prepared under different sintering conditions