Impact of Mn doping on structural, optical and dielectric properties of titanium-based double perovskite La2CuTi1-xMnxO6

A new series of La₂CuTi_1-xMn_xO₆ (x = 0.00, 0.05, 0.10, 0.15, 0.20, and 0.25) material was synthesized using the conventional solid-state method, and their structural, optical, and dielectric properties were studied using various techniques, including X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, Field-emission scanning electron microscopy (FESEM), High-Resolution Transmission Electron Microscopy (HRTEM), Electrical impedance spectroscopy (EIS), and UV–Vis spectroscopy. XRD and Rietveld refinement confirmed that Mn was successfully incorporated at the Ti site in an orthorhombic structure with Pnma space group. FESEM images indicated that grain sizes increased with increased doping while HRTEM images revealed high crystallinity. X-ray Photoelectron Spectroscopy (XPS) analysis findings confirmed the stability of La³⁺, Cu²⁺, and Ti⁴⁺ across both compositions of La₂CuTi_1-xMn_xO₆ (x = 0.00 and 0.20), while Mn⁴⁺ was effectively integrated into the doped sample. Additionally, the analysis revealed the presence of oxygen vacancies, which could enhance critical properties like charge transport and conductivity. The UV–Vis analysis showed that the band gap energy dropped from 2.06 eV to 1.62 eV as the doping level went from x = 0.00 to x = 0.25. Dielectric analysis indicated that both dielectric constants and tangent losses were higher at lower frequencies and decreased as the frequency increased. Significantly, La₂CuTi_1-xMn_xO₆ (x = 0.05) exhibited a higher dielectric constant than the parent compound, La₂CuTiO₆, highlighting the ability of doping to alter the dielectric properties of double perovskite materials.