• journal_title：American Mineralogist
• Contributor：Ming Zhang ; Ekhard K.H. Salje ; Ulrich Bismayer ; Lee A. Groat ; Thomas Malcherek
• Publisher：Mineralogical Society of America
• Date：2002-
• Format：text/html
• Language：en
• journal_abbrev：American Mineralogist
• issn：0003-004X
• volume：87
• issue：7
• firstpage：882
• section：Articles

Radiation damage and the recrystallization of natural titanite (CaTiSiO₅) were studied using infrared spectroscopy in the spectral range from 50 to 7500 cm⁻¹. The results show that radiation damage leads to systematic changes in spectral features: decreasing absorption and reflectivity, line broadening, and loss of orientational dependence. Strongly damaged titanite shows hydroxylate bands between 2200 and 3500 cm⁻¹. The band most affected by radiation damage is the Ti-O stretching band near 670 cm⁻¹. It shifts to 710 cm⁻¹ in the most damaged samples, possibly indicating the presence of TiO₅ complexes in metamict titanite. Titanite glasses (quenched melts of CaTiSiO₅) show spectral features different from those of radiation-damaged titanite, especially in the Ti-O and Si-O stretching regions.

Annealing radiation-damaged titanites at high temperatures results in the recovery of damaged crystalline regions. Recrystallization near 900 K is characterized by an increase in reflectivity, integrated absorbance, and line sharpening. Different infrared bands show recovery at different temperatures. The restoration of the Ti-O stretching band near 670 cm⁻¹ and an infrared band near 285 cm⁻¹ took place at temperatures of 1200–1400 K. Temperature-induced changes of the OH-absorption bands could be responsible for the previously reported differences in the temperature evolution of infrared spectra of OH species between in situ and quench experiments.