Non-180° domains formation mechanism in LiTaO3 grains of an Al2O3/LiTaO3 composite

High density (>99.5%) Al2O3/LiTaO3 (ALT) composite was obtained by hot pressing at 1300 °C/25 MPa in nitrogen atmosphere. The microstructure, which included a domain structure in LiTaO3 grains, was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Most of the domains observed in LiTaO3 grains of the Al2O3/LiTaO3 (ALT) composites belong to a non-180° type domain, which cannot exist in LiTaO3 single crystals. This non-symmetry domain microstructure belongs to ferroelectric twinning with {1¯012} twin composition plane. The non-180° domains formation mechanism was proposed.