Synthesis, optical and raman spectra of cobalt ditellurite, CoTe2O5 single crystal

Cobalt ditellurite (CoTe₂O₅) is a promising material for optical and vibrational applications; However, previous studies rarely combine structural and spectroscopic investigations to correlate crystal structure with optical behavior. The objective of this study is to synthesize and systematically analyze CoTe₂O₅ single crystals and establish the relationship between their structural and optical properties. The crystals were grown using slow-cooling flux technique with SiO and TiO₂ precursors and characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR), Raman, and UV-visible spectroscopy. Origin Pro and Python-based spectral peak-fitting tools were employed to perform Gaussian deconvolution and quantitative peak analysis. XRD confirmed an orthorhombic structure with the PNAB space group. FTIR spectra revealed six absorption bands within 550-3500 cm⁻¹ associated with Co-O and Ti-O vibrations, while Raman spectra displayed dominant modes at 430 and 630 cm⁻¹ corresponding to CoO₆ octahedral vibrations. Using the direct Tock relation (αhν)² versus hν the optical band gap was determined as 4.36 eV, indicating suitable insulating behavior for the optical material. Python-assisted spectral fitting reduced peak-fitting error by approximately 18% compared to manual fitting, thereby improving spectral interpretation reliability. These results confirm the structural integrity and optical capability of CoTe₂O₅ single crystals.