Assessing the amount of the anatase and rutile phases of TiO2 by optical reflectance measurements

The anatase (A) and rutile (R) phases of a series of titanium dioxide (TiO2) samples were investigated by optical diffuse reflectance spectroscopy. The samples consisted of commercial A and R high-purity TiO2 powders mixed together according to the Rmass/(Rmass + Amass) rutile mass ratio. The optical reflectance spectra of the A + R TiO2 mixtures are very distinctive and their derivatives presented a clear relationship with the rutile mass fraction − according to which the phase composition of TiO2 can be estimated with good precision. The optical bandgaps of the A + R TiO2 mixtures were also determined and correlated with the rutile mass ratio. In its current form, this work shows the potential of optical reflectance spectroscopy to (fast and reliably) estimate the amount of rutile (or anatase) phase in TiO2-based materials.