Dielectric and ferroelectric study of KNN modified NBT ceramics synthesized by microwave processing technique

Morphotropic phase boundary (MPB) composition, 0.93Na0.5Bi0.5TiO3–0.07K0.5Na0.5NbO3/NBT–KNN was synthesized by microwave heating. The optimized calcination conditions for single perovskite phase formation were 800 °C for 40 min, whereas the sintering was carried out at 1150 °C for 20, 30 and 40 min. The MPB composition, sintered for 30 min, showed better properties: nearly uniform and larger grain size of ∼2.52 μm, room temperature (RT) dielectric constant (εr) ∼1180 at 1 kHz, a relatively high bulk density (ρ) ∼5.49 g/cc, remnant polarization (2Pr) ∼3.3μC/cm2 and coercive field (Ec) ∼5.8 kV/cm. Diffuse phase transition was observed for all the ceramics with highest diffusivity factor, γ∼1.65 in MPB composition sintered for 30 min.