Impedance Spectroscopy of Fe and La-Doped BaTiO₃ Ceramics

A wide range of the interesting properties of electroceramics Ba0.996La0.004Ti0.999O3 (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 Ba0.996La0.004Ti1−yFeyO3 (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.