Structural, morphological and optical investigations of θ-Al2O3 ultrafine powder

Single-phase θ-Al2O3 nanopowder has been synthesized by co-precipitation technique. The synthesized powders were sintered at a temperature ranging from 900 to 1200 °C. A stable monoclinic phase is observed for the whole sintering temperature range. The purity, chemical bonds, morphology and optical properties of the powders were investigated by different characterization techniques. X-ray diffraction and Brunauer–Emmett–Teller analysis confirms the existence of ultrafine alumina powders with particle diameter of ∼5 nm and surface area of 100 m2/g. The novel optical results such as band gap of 5.8 eV would reveal the viability of observed phase of alumina in advanced semiconductor applications.