Normal to Relaxor Ferroelectric Transition and Domain Morphology Evolution in (K,Na)(Nb,Sb)O3–LiTaO3–BaZrO3 Lead‐Free Ceramics
A normal to relaxor ferroelectric transition was induced by the substitution of BaZrO3 for LiTaO3 in a typical lead‐free (K,Na)(Nb,Sb)O3–LiTaO3–BaZrO3
system and this was found to accompany a tetragonal to rhombohedral phase structural transformation. The typical relaxor behavior characterized by diffuse phase transition and frequency dispersion was identified by the measurement of frequency‐dependent dielectric permittivity. The
transmission electron microscopy studies demonstrated that the above phenomenon would be closely related to the domain morphology evolution from normal micron‐sized lamellar domains, to tweed‐like domains and finally to polar nanodomains. Selected area and convergent beam electron
diffraction patterns further confirmed that the composition (2.5 mol% BaZrO3) exhibited rhombohedral and tetragonal phase coexistence. The evolution of domain morphology with temperature also disclosed the diffuseness of ferroelectric phase transition.