Ceramics of the quasi-binary concentration section (0.1 ≤ x ≤ 0.2, Δx = 0.025) of the ternary solid solution system (0.5 − x)BiFeO₃-0.5PbFe_0.5Nb_0.5O₃-xPbTiO₃ were prepared by the conventional solid-phase reaction method. An X-ray study at different temperatures revealed that (0.5 − x)BF-0.5PFN-xPT ceramics have a cluster morphology. Clusters have different modulation, crystal lattice symmetry, and chemical composition. The presence of a cluster structure in a solid solution with heterovalent substitution, consisting of regions rich in Ti⁺⁴, Nb⁺⁵, or Fe³⁺, has led to the appearance of Maxwell–Wagner polarization in the studied ceramics. The study of the dielectric characteristics revealed the relaxor-like behavior of the studied ceramics. The grain morphology, dielectric, pyroelectric, and piezoelectric properties of the selected solid solutions were investigated. The highest piezoelectric coefficient, d₃₃ = 280 pC/N, was obtained in the 0.3BiFeO₃-0.5PbFe_0.5Nb_0.5O₃-0.2PbTiO₃ ceramics. Study of the dielectric characteristics of all samples revealed relaxor ferroelectric behavior and a region of diffuse phase transition from the paraelectric to ferroelectric phase in the temperature range of 140–170 °C.

This paper investigates the processes of phase formation of solid solutions of (1 − x)BaTi_0.85Zr_0.15O₃ − xAgNbO₃ where x = 0, 0.03, 0.06, 0.09. The optimal temperatures of synthesis and sintering are determined. From the results of X-ray diffraction analysis, it follows that all solid solutions have a perovskite-type structure. Analysis of the microstructure showed that the average grain size decreases at concentrations x = 0.03 and 0.06. Correlations between the cationic composition and dielectric characteristics of the studied solid solutions have been established. The values of the total stored energy and efficiency are determined. The maximum stored energy was found for a solid solution with x = 0.03 and amounted to 0.074 J∙cm⁻³ with an efficiency of 76.5%.

The physicochemical properties of solid solutions [Ba_1–xNa_x][Ti_1–yZr_yNb_x]O₃ with varying concentrations of NaNbO₃ (x = 0.02, 0.04) and BaZrO₃ (y = 0.00, 0.05, 0.10) are investigated. The samples are synthesized using a two-stage solid-state reaction method with preliminary mechanoactivation. X-ray diffraction analysis reveals that all samples feature a perovskite-like structure with minor impurity phases. Increasing the Zr⁴⁺ concentration leads to broadening of diffraction peaks and the appearance of diffuse maxima; this may indicate modulation effects and inhomogeneous cation (Zr⁴⁺, Ti⁴⁺, Nb⁵⁺) distribution. The unit cell parameter gradually increases from 4.009 to 4.037 Å as Zr⁴⁺ content grows from 0 to 10 mol %. The relative density of the ceramics reaches a maximum of 88.50% at y = 0.10. SEM analysis reveals an underdeveloped fine-grained microstructure (average grain size ≈ 2 μm) with pronounced porosity, attributed to low-melting eutectics forming a liquid phase during sintering. Studies of dielectric hysteresis loops demonstrate an increase in total energy density from 0.998 to 1.551 J/cm³, accompanied by a sharp decrease in energy efficiency from 56.1 to 10.8% when Zr⁴⁺ increases. The highest energy storage density is expected in the concentration range 0 ≤ y < 0.05. The results obtained can be applied to the development of lead-free ceramics based on BaTi_(1–y)Zr_yO₃.