Domain structures in hot-press sintered SrBi2Ta1.6Nb0.4O9 and SrBi2Ta2O9 ferroelectric ceramics

SrBi2Ta1.6Nb0.4O9 (SBTN) and SrBi2Ta2O9 (SBT) ceramics with typical bismuth layered perovskite structure were synthesized by hot-press sintering at 1000 °C for 2 h. The maximum relative density of as-sintered SBTN and SBT materials is 98.97%. The domain structure of SBTN and SBT was systemically characterized by means of TEM and HRTEM. The 90° domain walls were identified by the 90° rotation relationship of the electron diffraction pattern along the [0 0 1] zone axis. Irregular shaped and highly curved 180° domain wall were also observed in SBTN ceramics. The traditional α-fringes can be found in SBT, which are the evidence of large strains in hot-press sintering ceramics. Rod-like SrTa2O6 precipitates are also analyzed as well as its interface with the matrix.