Influence of synthesis route and calcination temperature on the structural and surface characteristics of anatase TiO₂ nanoparticles

This study comparatively investigates anatase TiO₂ nanoparticles synthesized via precipitation and sol–gel routes, followed by controlled calcination at 350 °C and 500 °C. Structural evolution was examined by X-ray diffraction (XRD) and Raman spectroscopy, while textural properties were analyzed using N₂ adsorption–desorption (BET/BJH). Optical characteristics were evaluated by diffuse reflectance UV–Vis spectroscopy and Tauc analysis.All samples exhibited phase-pure anatase after calcination, with crystallite sizes ranging from approximately 8–24 nm depending on synthesis pathway and thermal treatment. The sol–gel route at 350 °C delivered the highest specific surface area (∼119 m² g⁻¹), whereas higher calcination temperature led to crystallite growth and surface area reduction for both synthesis methods. A consistent inverse correlation between crystallite size and surface area was observed. Band-gap energies varied slightly between 3.03 and 3.11 eV, reflecting differences in crystallinity and structural order. The results demonstrate that synthesis route and calcination temperature jointly govern microstructural development and surface characteristics of anatase TiO₂ nanoparticles, providing a clear structure–property relationship relevant for photocatalytic and surface-driven applications.