Titanium solid-state NMR in anatase, brookite and rutile

We report 47Ti and 49Ti NMR spectra of powdered samples of the three common phases of titania, TiO2. The linewidths are dominated by the electric quadrupole interaction. The relative linewidths of the three samples cannot be explained in terms of simple structural symmetry using point charges. This indicates that a significant amount of the TiO interaction is covalent in nature.