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

Abstract

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.