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Multifunctional lead-free La0.67Ca0.2Ba0.13Fe0.97Cr0.03O3 perovskite nanoceramics: Comprehensive structural, electrical, dielectric and gas sensing analysis
Authors: Toumi, M.; Dhahri, A.; Benali, A.; Dhahri, R.; Costa, B.F.O.; Dhahri, E.
Ref.: J. Alloys Compd. 1048, 185035 (2025)
Abstract: This study reports the development and comprehensive characterization of the complex La0.67Ca0.2Ba0.13-Fe0.97Cr0.03O3 using the auto-combustion technique. The work thoroughly assesses the perturbation of Cr insertion on its structural, electrical, and gas sensing attributes. X-ray scattering analysis confirmed the formation of an orthorhombic form with the Pnma space group. Complementary Raman spectroscopy confirmed the phase purity of the synthesized La0.67Ca0.2Ba0.13Fe0.97Cr0.03O3, revealing the characteristic pattern of its structure. Transmission electron microscopy (TEM) revealed the presence of fine nanoparticles, and Energy-Dispersive Xray Spectroscopy (EDAX) analysis further verified the targeted elemental stoichiometry. Impedance spectroscopy, conducted over the temperature interval of 160-360 K and frequency range of 102Hz to 106Hz, demonstrated significant modifications in the electrical response induced by Cr incorporation, as evidenced by lower resistance and activation energy. The Nyquist plots were analyzed using an equivalent circuit model to differentiate between grain and grain boundary contributions. The permittivity exhibited typical dielectric relaxation behavior. AC resistivity measurements suggested that electrical conduction obeys the non-overlapping small polaron tunneling (NSPT) mechanism. This was supported by the scaling of resistivity with frequency and temperature. Further, the study includes analysis of the electric modulus M", which also showed a clear relaxation peaks, and its scaling behavior, confirming the temperature-independent nature of the underlying relaxation mechanism. The Cr-doped sample exhibited improved dielectric characteristics. The complex showed high sensitivity to acetone and ethanol vapors, underscoring the effectiveness of co-replacements in tuning the multifunctional behavior of perovskite oxides for applications in electronics and gas sensing.
