Solid-state Ti-47,Ti-49 NMR determination of the phase distribution of titania nanoparticles

Ti-47,Ti-49 solid-state NMR spectra are reported from TiO2 nanoparticles. P articles heated below 700 degreesC are predominantly anatase. The correspon ding 47,49Ti NMR spectra can be simulated by using the NMR interaction para meters determined from bulk polycrystalline TiO2 with an additional Lorentz ian smoothing, which increases as the particle size, as determined by X-ray diffraction, decreases. Above 700 degreesC conversion to rutile increases with increasing calcination temperature. XRD and solid-state NMR/provide co mplementary quantification of the phase distribution with very good agreeme nt between the techniques when there are comparable quantities of rutile an d anatase present. At low anatase content NMR is more sensitive to the phas e distribution.