Evolution of domain structure in 0.96(K_0.48Na_0.52)(Nb_0.96Sb_0.04)O₃0.04(Bi_0.50Na_0.50)ZrO₃ ceramics with poling and temperature

Domain structure often has significant influences on both piezoelectric properties and piezoelectric temperature stability of a ferroelectric ceramic. In-depth studies on the characters of domain structure should be helpful for the better understanding of piezoelectric performance. In this work, the evolution of domain structure in large-d₃₃ 0.96(K_0.48Na_0.52)(Nb_0.96Sb_0.04)O₃−0.04(Bi_0.50Na_0.50)ZrO₃ ceramics with poling and temperature was systematically investigated via comparing the various domain patterns that are obtained by acid-etching. It was found that domain structure changes greatly upon poling and varies largely with temperature. Complex domain patterns consisting of long narrow parallel stripes or herringbone structure separated by 180°-domain boundaries are observed in the unpoled ceramics at room temperature. Domain patterns become less complicated upon poling, due to the collective polarization reversals of parallel-stripe domain clusters and banded fine-stripe domain segments. Parallel stripes and herringbone bands become much wider upon poling, as some narrow stripes and herringbone bands coalesce into broad ones, respectively. Hierarchical domain structure is commonly seen in the domain patterns acid-etched at room temperature, but is less frequently recognized at elevated temperatures. Schematic models of domain configurations were proposed to explain the domain structure and its evolution with poling.