Configurations of ferroelectric domains in bismuth- and Zinc-modified Pb(Ni1/3Nb2/3)O3-PbTiO3-PbZrO3 ceramics

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Abstract

Transmission electron microscopy was used to investigate the domain structures of the (Pb0.985Bi0.01)(Ni1/4Zn1/12Nb2/3)0.2(ZrσTi1−σ)0.8O3 (0.30 ≤ σ ≤ 0.70) ceramics, which are located in the ferroelectric tetragonal and rhombohedral phase regions, and also near the morphotropic phase boundary (MPB). The results show that the lamellar twinning domains and the δ-fringe contrast are most frequently observed in the compositions located in the ferroelectrc tetragonal phase region. In the compositions near the MPB, a banded domain structure similar to herringbone pattern is observed, which contains many parallel bands forming 90° or 70° angles whereas they are inconsistent with one another on both sides of the herringbone domain patterns. The morphology of the herringbone domain structure observed in the bismuth- and zinc-modified PNN-PZ-PT ceramics with composition near the MPB can be described by a space-stacking succession of two crystallographically equivalent plates whereas made from different twin-related domains, with the same habit plane parallel to the (011)-type plane. In the compositions located in the rhombohedral phase region, the stripelike domains are observed, and a local random contrast representing short-range-ordered ‘island’-typed polar clusters or nanodomains is also found, which is attributed to the existence of the polar microregions with the dispersed nanometer-sized short-range-ordered domains in the rhombohedral matrix, because the free energy of the ensembl e of the polar microregion is lowered, and the relative thermodynamic stability is increased with increasing the content ratio of Zr to Ti. In addition, the wavy character in the thickness fringe is commonly observed at the fringe of thin foil, which is due to continuous bending of the thin foil at various equivalent directions.

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