Domain configurations in relaxor ferroelectric single crystals Pb(Mg_1/3Nb_2/3)O₃–PbTiO₃

The 90° macrodomains in tetragonal Pb(Mg_1/3Nb_2/3)O₃–PbTiO₃ (PMNT) crystals take the shape of coarse and straight strips under optical microscopes and scanning electron acoustic microscopes. However, 71° or 109° domains in rhombohedral PMNT crystals are relatively poor in contrast and become clearer, coarser and straighter as their composition becomes closer to morphotropic phase boundaries, showing an evolution series of micro-to-macro domain transformation. Moreover, domain configurations are also dependent on the nucleation and growth rate of domains, the crystal defects, and the cooling rate through Curie temperature. The appearance of macrodomains arises from the strengthening of depolarization field and the weakening of random field.