Intermediate structures in radiation damaged titanite (CaTiSiO5): a Raman spectroscopic study

Area of Science:

• Mineral physics
• Materials science
• Geochemistry

Background:

• Natural titanite (CaTiSiO(5)) is a common accessory mineral in various igneous and metamorphic rocks.
• Understanding its structural response to radiation damage and thermal treatment is crucial for geological dating and material science applications.

Purpose of the Study:

• To investigate the effects of radiation damage and thermal annealing on the crystal structure of natural titanite using Raman spectroscopy.
• To clarify the structural symmetry of well-crystallized titanite and the evolution of its structure under different conditions.

Main Methods:

• Raman spectroscopy was employed to analyze natural titanite samples with varying degrees of radiation damage.
• Samples were subjected to thermal annealing at different temperatures to observe structural recovery and phase transformations.

Main Results:

• Well-crystallized titanite exhibits P2(1)/a symmetry, differing from previously reported A2/a symmetry.
• Radiation damage from impurities like U and Th leads to amorphization, characterized by spectral changes.
• Annealing promotes structural recovery, restoring the P2(1)/a symmetry in weakly damaged samples.
• Highly damaged titanite recrystallizes into an A2/a phase upon annealing, with further modifications at higher temperatures, but recovery remains incomplete.

Conclusions:

• The crystal structure of titanite is sensitive to radiation damage and thermal history.
• Raman spectroscopy is effective in characterizing structural changes and symmetry in titanite.
• The degree of initial damage significantly influences the effectiveness of thermal annealing for structural restoration.