Synthesis and study of the structural and dielectric properties of La0.67Ca0.2Ba0.13Fe1−xMnxO3 ferrites (x = 0, 0.03 and 0.06)

Abstract

The La0.67Ca0.2Ba0.13Fe1−xMnxO3 perovskite compounds with different manganese concentrations (x = 0.0, 0.03, 0.06) were synthesized by the autocombustion method and annealed at 700 °C. The X-ray diffraction (XRD) data indicated that all obtained compounds crystallize in the cubic structure with the Pm $$\overline{3}$$ m space group. The increase in the substitution rate has been found to lead to the decrease in the crystallite size value characterized by X-ray diffraction. The dielectric properties of these samples, using a complex impedance spectroscopy technique, were also performed as a function of frequency and temperature. A suitable equivalent electrical circuit was used to assess the contributions of electrode, grains, and grain boundaries in the complex impedance results. Activation energies were determined from different methods. Nyquist plots were consistent with three circuits in series, each one with a capacitance in parallel with a resistance. The conduction mechanism follows the NSPT model for the three samples at T < 280 K, in which the rise in substitution rate increases the binding energy of carriers. Above 280 K, the appropriate model is the Correlated Barrier Hopping (CBH) for x = 0, while the overlapping large polaron tunneling (OLPT) process has been confirmed for both samples x = 0.03 and x = 0.06. Our compounds have high electrical properties, and good thermal and chemical stability. They are susceptible to many technological applications, such as gas sensors, capacitors, filters, resonators, new read heads, and solid oxide fuel cells.