Dehydration of metamict titanite: An infrared spectroscopic study

We carried out a study of dehydration in natural metamict and crystalline samples of titanite between 20 and 1060 K. Infrared absorption spectra of crystalline titanite show at least five O-H stretching bands in the region between 2000 and 4500 cm(-1) Metamict samples show a broad distribution of stretching modes between 2500 and 3700 cm(-1). The annealing of metamict titanite was studied by LR absorption spectroscopy under in situ and ex situ heating conditions. Heating a sample at high temperature leads to an irreversible decrease of the absorption signal of the O-H stretching bands, together with a significant sharpening of the band profile. The O-H bands in the metamict material show no preferential polarization. Annealing leads to a dramatic anisotropy of the IR absorption spectra. We believe that the recrystallization behavior of a metamict sample is correlated with its dehydration.