Structural and nano-composite features of TiO2–Al2O3 powders prepared by sol–gel method

In this investigation titania–alumina nanocomposites containing various compositions of titania and alumina were successfully prepared by controlled sol–gel method in attempt to study the structure, nature of phases, particle size and morphology of the composite samples. The structural changes and phase analysis were monitored by XRD, FTIR and SEM where the surface area was estimated by BET analysis. The particle size of the composite samples is in nanometric dimensions (18–40 nm). The role of alumina content on the structural properties, phase transformation, surface area and particle size of titania was investigated. The resulting mixed oxides possess rutile phase at low alumina content (up to 20%) and anatase phase is predominant at high alumina content (40–90%). The XRD results reveal that the grain size of the mixed oxides is reduced upon increasing in the alumina content indicating that alumina can effectively prevent titania particles from further growing up in the process of calcination. This is confirmed by large increase in the specific surface area for the composite samples. In addition tialite (Al2TiO5) compound was detected in composites with high content of alumina.