- Tytuł:
- Local Phenomena in meta-mict Titanite
- Autorzy:
-
Bismayer, U.
Paulmann, C.
Groat, L.
Zhang, M. - Powiązania:
- https://bibliotekanauki.pl/articles/1550076.pdf
- Data publikacji:
- 2010-01
- Wydawca:
- Polska Akademia Nauk. Instytut Fizyki PAN
- Tematy:
-
23.60.+e
61.43.-j
62.23.-c
78.30.-j
81.40.-z - Opis:
- 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.
- Źródło:
-
Acta Physica Polonica A; 2010, 117, 1; 74-77
0587-4246
1898-794X - Pojawia się w:
- Acta Physica Polonica A
- Dostawca treści:
- Biblioteka Nauki
Artykuł