Structural and Optical Properties of Ca₂Mn₂O₆ Double Perovskite: Insights into its Potential for Photocatalytic Applications

Calcium manganite double perovskite, Ca₂Mn₂O₆, was synthesized by a solid-state method to explore its photocatalytic potential, governed by the Mn⁴⁺/ Mn³⁺ redox couple. The structural and phase characteristics were analyzed using X-ray diffraction (XRD), Raman, and Fourier transform infrared (FTIR) spectroscopies. Raman analysis confirmed the existence of Jahn-Teller distortions in the lattice arising from Mn³⁺ and Mn⁴⁺ ions, suggesting the presence of tensile strain in the material. Additionally, infrared spectra identified the functional groups in the material, showing a Mn-O stretching vibration at 525 cm^-1 and a Mn-O-Mn bending vibration at 479 cm^-1. Optical investigations through UV-vis spectroscopy revealed a higher Urbach energy, further confirmed by photoluminescence (PL) emissions in the visible region, which were associated with defect states. A low optical band gap of 2.50 eV was observed, enhancing photocatalytic activity under white-light irradiation due to the strong oxidizing power of photogenerated holes. Additionally, magnetic studies confirmed the paramagnetic characteristics of Ca₂Mn₂O₆, attributed to transition metal Mn ions in the structure. Compared with previously studied calcium manganese oxides, Ca₂Mn₂O₆ exhibits unique structural and optical properties, making it a viable option for photocatalytic and energy-related applications.