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)

• 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.

References

• 1. J.A. Speer, G.V. Gibbs, Am. Mineral. 61, 238 (1976)
• 2. S. Kek, M. Aroyo, U. Bismayer, C. Schmidt, K. Eichhorn, H.G. Krane, Z. Kristallogr. 212, 9 (1997)
• 3. F.C. Hawthorne, L.A. Groat, M. Raudsepp, N.A. Ball, M. Kimata, F. Spike, R. Gaba, N.M. Halden, G.R. Lumpkin, R.C. Ewing, R.B. Greegor, F.W. Lytle, T.S. Ercit, G.R. Rossman, F.J. Wicks, R.A. Ramik, B.L. Sherriff, M.E. Fleet, C. McCammon, Am. Mineral. 76, 370 (1991)
• 4. F. Farges, Am. Mineral. 82, 44 (1997)
• 5. M. Zhang, E.K.H. Salje, U. Bismayer, L.A. Groat, T. Malcherek, Am. Mineral. 87, 882 (2002)
• 6. C. Paulmann, U. Bismayer, L.A. Groat, Z. Kristallogr. 215, 678 (2000)
• 7. R.C. Ewing, A. Meldrum, LuMin Wang, ShiXin Wang, Rev. Mineral. Geochem., Min. Soc. America 39, 319 (2000)
• 8. T. Malcherek, C. Paulmann, M.C. Domeneghetti, U. Bismayer, J. Appl. Crystallogr. 34, 108 (2001)
• 9. H.-W. Meyer, U. Bismayer, G. Adiwidjaja, M. Zhang, L. Nistor, G. Van Tendelo, Phase Transit. 67, 271 (1998)
• 10. H.W. Meyer, M. Zang, U. Bismayer, E.K.H. Salje, C. Schmidt, S. Kek, W. Morgenroth, T. Bleser, Phase Transit. 59, 39 (1996)
• 11. I. Tanaka, T. Obuchi, H. Kohima, J. Cryst. Growth 87, 169 (1988)
• 12. U. Bismayer, Rev. Mineral. Geochem. 39, 265 (2000)
• 13. P. Tolédano, U. Bismayer, J. Phys., Condens. Matter 17, 6627 (2005)

Identifiers

DOI

10.12693/APhysPolA.117.74