SAED and TEM investigations of domain structure in bismuth- and zinc-modified Pb(Ni1/3Nb2/3)O3-PbTiO3-PbZrO3 ceramics at morphotropic phase boundary

Transmission electron microscopy and electron diffraction investigations of the ferroelectric domain structures in the Bi- and Zn-modified Pb(Ni1/3Nb2/3)O-3-PbTiO3-PbZrO3 (PNN-PT-PZ) ceramics at the morphotropic phase boundary (MPB) revealed the triplet splitting of electron diffraction spots due to the coexistence of the tetragonal (T-1 and T-2) and rhombohedral (R) phases at the microscopic Ferroelectric-domain level. The angular values formed between the parallel stripes in the herringbone domain pattern can be explained by a model of spatial domain configuration previously proposed for BaTiO3 ceramics. A succession model of ferroelectric domain structures T-1 RT 2RT(1)...is proposed to explain the coexistence of T and R phases in:the same ceramic grain at the MPB. The elastically stored energy in the mixed T-R wall was estimated, and its uniform distribution confirms this succession model.