Fabrication and dielectric properties of textured Na _0.5 Bi _0.5TiO ₃-BaTiO ₃ ceramics by RTGG method

Grain-oriented Na _0.5Bi _0.5TiO ₃ -BaTiO ₃ (NBTBT) ceramics were fabricated by reactive-templated grain growth using plate-like Bi _2.5 Na _3.5Nb ₅O ₁₈ (BNN) as templates. The specimens are composed of NBTBT perovskite phase and BNN lay-structured phase. Textured ceramics have a brick-wall microstructure with strip-like grains aligning in the direction parallel to the casting plane and exhibit an {h00} preferred orientation. The texture fraction increases initially, and then decreases with increasing sintering temperature. The optimal sintering temperature is 1,185°C where the texture fraction has a maximum value of 0.58 and d ₃₃ is 98 pC/N. The textured NBTBT ceramics show evidence of relaxor ferroelectrics with diffuse phase transition and frequency dispersion because of composite biphasic structure.