Synthesis and Characterization of CaFe₂O₄: Catalytic and Bactericidal Evaluation at High Temperatures

CaFe₂O₄ is a p-type ferrite semiconductor of interest for photo-assisted environmental remediation due to its narrow band gap and high chemical stability. In this work, CaFe₂O₄ powders were synthesized via the Pechini polymeric precursor method and calcined between 550 and 850 °C to investigate the influence of calcination temperature on structural order and material properties. X-ray diffraction combined with Rietveld refinement revealed the progressive stabilization of the orthorhombic Pnma phase, accompanied by relaxation of the FeO₆ octahedral framework. Raman and FT-IR spectroscopies confirmed a significant increase in vibrational coherence with increasing calcination temperature, quantified by a nearly three-fold increase in the global Raman order parameter and phonon lifetimes. Nitrogen physisorption showed a modest specific surface area and a pore system dominated by interparticle meso-macroporosity, typical of thermally treated ferrites. Removal tests using ciprofloxacin under UV-A irradiation showed limited photo-assisted activity, while agar diffusion assays against Escherichia coli and Staphylococcus aureus revealed no inhibition halos, indicating the absence of detectable antibacterial activity under the experimental conditions employed. Overall, CaFe₂O₄ combines photo-assisted response with good structural stability, highlighting its potential as a chemically stable ceramic material with no detectable antibacterial activity under the tested conditions.