A wide range of the interesting properties of electroceramics Ba_0.996La_0.004Ti_0.999O₃ (BLT4) undoubtedly deserves differentiation and optimization. For this purpose, the corresponding donor oxide dope Fe₂O₃ was introduced in excess quantities into the base ceramics. In this way, an innovative ceramic material with the general formula of Ba_0.996La_0.004Ti_1−yFe_yO₃ (BLTF), for y = 0.001, 0.002, 0.003, 0.004, has been produced. The crystal structure of BLTF ceramics was investigated using X-ray diffraction. The diffraction peaks in XRD confirm the formation of the tetragonal perovskite phase. The electrical properties of BLTF ceramics have been tested using impedance spectroscopy, in the frequency range of 20 Hz–2 MHz and the temperature range of 20–580 °C. To gain absolute certainty on the consistency of the measured data, the obtained impedance spectra were analyzed using the Kramers–Kronig method. The usage of an equivalent circuit, proposed by the authors, allowed grain and grain boundary resistivity to be obtained. Based on the diagram of the natural logarithm of the mentioned resistivity versus the reciprocal absolute temperature, the activation energies of the conductivity processes have been determined. The values of activation energies indicated that the admixture of iron introduced into the BLT4 ceramics played a crucial role in the conductivity of grains and intergranular borders.

The solid solution of the perovskite type structure Ba_0.996La_0.004Ti_1−yFe_yO₃ (BLTF) for varying iron content (y = 0.1−0.4 mol.%) was obtained as a result of a solid state reaction using the conventional method. At room temperature (Tr < T_C), the as-received ceramics reveals a single-phase, tetragonal structure and a P4mm space group. An increase in the iron content causes a slight decrease in the volume of the elementary cell. In addition, this admixture significantly reduces the maximum permittivity value (ε_m) and the shift of the phase transition temperature (T_C) towards lower temperatures. The BLTF solid solution shows a classical phase transition and low values of dielectric loss tangent (tgδ), both at room temperature and in the phase transition area. The Curie–Weiss temperature (T₀) and Curie constant (C) were also determined on the basis of the dielectric measurements results. The analysis of temperature changes in DC conductivity revealed presence of the positive temperature coefficient of resistivity (PTCR) effect in the phase transition area.

In the present study BaTiO₃ and Ba_1-xLa_xTiO₃ (0.1-0.4mol.% La) ceramic powders were synthesized by the conventional mixed oxide method (MOM). The characterization of the ceramic powders was carried out using a simultaneous thermal analysis (STA), with a combined DTA/TG/DTG system (Netzsch STA409). The results of thermal analysis allowed to determine the optimal temperature of synthesis. Microstructure was investigated by scanning electron microscopy (SEM), crystalline structure was studied by X-ray diffraction method (XRD). The EDS investigations showed that samples exhibited conservation of stoichiometry according to the chemical composition formula. The X-ray diffraction analysis confirmed formation of the desired crystalline structure both pure and La3+-doped BaTiO₃ ceramics exhibiting a perovskite-type structure ABO3 with tetragonal symmetry P4 mm.

Lanthanum-modified BaTiO₃ electroceramic materials have superior dielectric and piezoelectric properties. Ba_0.996La_0.004Ti_0.999O₃ (BLT4) seems to be a serious candidate for ultracondensator applications. This manuscript describes the results of hafnium and europium modification of BLT 4 ceramics. The pure and doped ceramic materials were synthesized by the conventional mixed oxide method. The microstructure of obtained samples was examined by scanning electron microscope. The investigations reveal strong correlations between the presence of admixture and the grain size, which was especially visible in the case of the hafnium dopant. The frequency and temperature dielectric characteristics measurements revealed a decrease in electric permittivity. Moreover, the impedance spectroscopy investigations showed severe changes in grains and grain-boundary resistivity, which was connected with changes in electric conductivity.

This paper describes the properties of a lead-free ceramic material based on barium titanate, designed for the construction of ultracapacitors and sensors used in mechatronic systems. The admixture of lanthanum (La³⁺) served as a modifier. The ceramic powders were obtained by the solid phase reaction method (conventional method—mixed oxides method—MOM). Technological conditions of the synthesis process were determined on the basis of thermal analysis. The obtained samples are characterized, at room temperature (T_r < T_C), by a single-phase tetragonal structure and a P4mm space group. Properly developed large grains (d = 5 µm) contributed to the increase in electric permittivity, the maximum value of which is at the level of ε_m ≈ 112,000, as well as to a strong decrease in specific resistance in the ferroelectric phase, whereas above the Curie temperature, by creating a potential barrier at their boundaries, there was a a rapid increase in resistivity. The temperature coefficient of resistance of the obtained posistor is 10.53%/K. The electrical properties of the obtained ceramics were examined using impedance spectroscopy. In order to analyze the obtained results, a method of comparing the behavior of the real object and its replacement system in a specific frequency region was used, whereas the Kramer–-Kroning (K–K) test was used to determine the consistency of the measured data. The proper selection of the stoichiometry and synthesis conditions resulted in the creation of an appropriate concentration of donor levels and oxygen gaps, which in turn resulted in a significant increase in the value of electrical permittivity, with small values of the angle of dielectric loss tangent. This fact predisposes the discussed material for certain applications (in the construction of ultracapacitors, among others).