Published online by Cambridge University Press: 01 February 2011
The optical band gap related to the electronic structures as well as the refractive index function of the electronic polarizability of the network can be tailored by changing the nature and the number of anions into the vicinity of cations. New routes have been developed in order to prepare new divided Ti(IV)-based oxyfluorinated compounds. In these compounds, the optical absorptions appear at the UV-Vis frontier and the refractive index is always smaller than the one of equivalent oxides. The chemical bonding, the hybridation and the density of the network play key roles in the variation of the optical band gap and the refractive index. For this family of titanium-based oxyfluorides containing mixed anions, chemical compositions and structural features have been correlated to the optical band gap and the refractive index, i.e. the complex index of materials n(λ) + ik(λ). Several examples will be given in order to illustrate the potentialities of these new inorganic compounds by changing the F/Ti ratio and the cationic substitution.