Study of the structure and ferroelectric properties of 1 % barium doped KNN-based ceramics using combined analytical methods

The problem of assessing the quality of non-toxic, environmentally safe pure KNN-based ceramics is of vital importance for potential applications in various fields including actuators, piezoelectric gages, and ferroelectric memory (FeRAM). In this work, we carried out a combined study of the chemical composition (XPS), structure (XRD), and ferroelectric properties (PFM) aiming at understanding the effect of doping with 1 mol.% Ba and solid-state synthesis conditions on the quality of KNN-based ceramics. The microstructural images and element maps have been obtained using SEM and EDX. The dielectric permittivity of the material has been studied as a function of temperature. The composition of the secondary P4/mbm K₆Nb_10.8O₃₀ phase has been identified. We show that Ba doping during two-stage solid-state synthesis reduces the secondary phase content from 15 % to 8 % and improves the ferroelectric properties of the material. However, it was found that the synthesis method has a predominant effect on the secondary phase content. The use of two-stage synthesis instead of one-stage synthesis reduces the secondary phase content from 30 % to 8 %.