Local Phenomena in meta-mict Titanite

• Authors: U. Bismayer , C. Paulmann , L. Groat , M. Zhang
• Languages of publication: EN

Abstracts

EN

Pure titanite is a mineral with chemical composition CaTiSiO_{5}. Its structure consists of corner linked TiO_{6}-octahedra, SiO_{4}-tetrahedra and sevenfold coordinated Ca positions. In nature various impurities like U and Th can be incorporated in the structure showing alpha and beta radiation. On meta-mictization, a process which occurs in nature when a mineral is exposed to radioactive irradiation, strong modifications of the structure are observed. Recoil processes due to alpha radiation change over geological time scales the originally periodically structured material into a quasi-amorphous state with persisting short-range order but destroyed long-range order. We report IR and Raman spectra as well as X-ray diffraction data of meta-mict and heat treated titanite from the Cardiff mine, Canada. IR as well as the Raman modes are strongly broadened in the meta-mict material and sharpen on annealing. The OH-stretching mode at 3486 cm^{-1} indicates strong changes in the local environment of OH in meta-mict titanite. The appearance of the Raman excitations between 620 and 750 cm^{-1} in meta-mict titanite, which in IR spectra are due to Ti-O stretching from TiO_{6} octahedra, indicates the breakdown of the Raman selection rules. This points to the breaking of the octahedral symmetry of TiO_{6} polyhedra.

Keywords

EN

23.60.+e; 61.43.-j; 62.23.-c; 78.30.-j; 81.40.-z

Discipline

• 62.23.-c: Structural classes of nanoscale systems(see also 81.07.-b Nanoscale materials and structures: fabrication and characterization in materials science)
• 61.43.-j: Disordered solids(see also 81.05.Gc Amorphous semiconductors, 81.05.Kf Glasses, and 81.05.Rm Porous materials; granular materials in materials science; for photoluminescence of disordered solids, see 78.55.Mb and 78.55.Qr)
• 23.60.+e: α decay
• 81.40.-z: Treatment of materials and its effects on microstructure, nanostructure, and properties
• 78.30.-j: Infrared and Raman spectra(for vibrational states in crystals and disordered systems, see 63.20.-e and 63.50.-x, respectively; for Raman spectra of superconductors, see 74.25.nd)

• Publisher: Institute of Physics, Polish Academy of Sciences
• Journal: Acta Physica Polonica A
• Year: 2010
• Volume: 117
• Issue: 1
• Pages: 74-77

Dates

published

2010-01

Contributors

author

U. Bismayer

• Mineralogisch-Petrographisches Institut, Universität Hamburg, Grindellee 48, 20146 Hamburg, Germany

author

C. Paulmann

• Mineralogisch-Petrographisches Institut, Universität Hamburg, Grindellee 48, 20146 Hamburg, Germany

author

L. Groat

• Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada

author

M. Zhang

• Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EQ, U.K.

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Identifiers

DOI

10.12693/APhysPolA.117.74