Intrinsic and extrinsic dielectric contributions to the electrical properties in CaZrO₃-doped KNN-based electrical/optical multifunctional ceramics

In this work, (0.9985 − x)(K_0.49Na_0.49Li_0.02)(Nb_0.8Ta_0.2)O₃–0.0015Ho₂O₃–xmol%CaZrO₃ (KNLNT–Ho–xCZ) lead-free piezoelectric ceramics were prepared by traditional solid-state reaction method. Dielectric, ferroelectric, photoluminescence properties and Rayleigh behavior were studied. The addition of CaZrO₃ caused the orthorhombic to tetragonal phase transition temperature T_O–T to decrease, and when x ≥ 0.02, the phase structure was converted from orthorhombic–tetragonal coexistence phases to pseudo-cubic one. With the addition of CaZrO₃, grain size showed a decreasing trend. Under a wavelength of 453 nm excitation, a strong green emission (~ 551 nm) was observed, corresponding to the transitions of ⁵S₂ → ⁵I₈. Furthermore, Rayleigh analysis showed that doping CaZrO₃ reduced the grain size and clamped the domains, making the domain wall movement and domain switching difficult, thus weakening the extrinsic contribution of ceramics.