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

In this work, (0.9985 − x)(K0.49Na0.49Li0.02)(Nb0.8Ta0.2)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 TO–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.