Domain morphology evolution associated with the relaxor–normal ferroelectric transition in the Bi- and Zn-modified Pb(Ni1/3Nb2/3)O3–PbZrO3–PbTiO3 system

To understand the dielectric behavior from a viewpoint of domain configuration, the domain morphology evolution in (Pb0.985Bi0.01)(Ni1/4Zn1/12Nb2/3)0.2(Zr1-σTiσ)0.8O3 ceramics (0.30⩽σ⩽0.60) has been investigated by transmission electron microscopy and high resolution electron microscopy. The results indicated that the domain morphology evolved from the normal micron-sized domains to herringbone domain patterns, and finally to the polar nanodoamains approximately 3∼6 nm in size when the PT content was decreased from 60 to 30 mol%. The normal twin-related 90° macrodomains are closely correlated with the normal dielectric response of the composition with higher PT content, whereas the relaxor response of the composition with lower PT content is directly attributable to nanometer domains that contain 1:1 short-range ordering on the B-site sub-lattice. A model is proposed to describe the effect of the PbTiO3 content on the ferroelectric domain morphology evolution in the system.