Deep insights into the conduction mechanisms in lead free perovskites Ba_0.75Sr_0.25Ti_1-xSn_xO₃ (0 ≤ x ≤ 0.10) ceramics

The lead-free perovskite Ba_0.75Sr_0.25Ti_1-xSn_xO₃ (x = 0, 0.03, 0.05, 0.1) was synthesized via the sol-gel method. X-ray diffraction (XRD) analysis confirmed the formation of a pure phase with a tetragonal structure belonging to the P4mm space group. Further Rietveld refinement provided in-depth insight into the structural parameters. Deconvoluted Raman spectra corroborated the tetragonal symmetry and revealed the presence of characteristic vibrational modes. Scanning electron microscopy (SEM) images demonstrated uniformly dense, cubic-shaped grains with well-defined grain boundaries, while energy-dispersive X-ray (EDX) analysis confirmed the presence of all constituent elements in the desired stoichiometric ratios. The dielectric and electrical properties were systematically investigated, and the Quantum Mechanical Tunneling (QMT) and Correlated Barrier Hopping (CBH) models were identified as suitable theoretical frameworks to describe the conduction mechanisms, based on temperature-dependent frequency exponent (S₁ and S₂) values. Moreover, the observed increase in DC conductivity with temperature confirms the semiconducting behavior of these ceramics.