Unmodified lead ferroniobate (PFN) and samples modified with 1 wt % Li₂CO₃ (PFNL) and 1 wt % MnO₂ (PFNM) have been prepared by solid-state reactions followed by sintering by a conventional ceramic processing technique. The modifiers have been shown to change the nature of the recrystallization sintering process, reduce the optimal sintering temperature of the material, increase its average grain size, stabilize its dielectric properties, and improve its piezoelectric performance. The observed effects are interpreted in terms of the crystal-chemical specifics of the modifiers and their location in the structure of the parent compound.

Pure and superstoichiometric modified by 2[ ]wt.% Bi₂O₃ and 2[ ]wt.% manganese oxide (Mn₂O₃) ceramic samples of the binary system 0.71BiFeO₃-0.29BaTiO₃ were fabricated using conventional ceramic technology by double solid-phase synthesis with following sintering. Mechanical activation of synthesized powders was carried out at the stage of manufacturing press powders prepared for sintering. X-ray analysis at room temperature showed that all studied ceramics have pseudo-cubic symmetry. Grain morphology, dielectric and piezoelectric properties of selected solid solutions were investigated. The modification increased the homogeneity of the material, dielectric constant and piezomodulus [ ] and also resulted in a decrease in the dielectric loss tangent. The highest piezoelectric coefficient [ ] [ ]pC/N was obtained. Dielectric characteristics of ceramics revealed ferroelectric relaxor behavior and region of diffuse phase transition from the paraelectric to ferroelectric phase in the temperature range of 740–770[ ]K.

Ceramic samples of solid solutions of the binary system (1−x)BiFeO₃-xBaTiO₃ + 2 wt.% Bi₂O₃ (0.29 ≤ x ≤ 0.33, Δx = 0.01) were prepared using the conventional solid-phase reaction method with and without mechanical activation. Using X-ray studies, it was found that the objects have a pseudocubic crystal structure, and limited solubility occurs in solid solutions of the studied composition, as evidenced by the presence of regions with an increased Bi or Ba content and similar cell parameters. A diffuse phase transition occurred from the FE to PE state in the temperature ranges of (650–850) K. Relaxor-like behavior and the smearing of the phase transition in the studied ceramics can be associated with the presence of non-interacting regions with an increased content of Bi or Ba, different modulation, and crystal lattice symmetry. The grain morphology and dielectric characteristics of the selected solid solutions were investigated. The highest piezoelectric coefficient, d₃₃ = 120 pC/N, was obtained in the mechanically activated ceramics 0.71BiFeO₃-0.29BaTiO₃ + 2 wt.% Bi₂O₃.