TY  - JOUR
AU  - Beirau, T.
AU  - Mihailova, B.
AU  - Malcherek, T.
AU  - Paulmann, C.
AU  - Bismayer, U.
AU  - Groat, L. A.
TI  - Temperature-induced P21/c to C2/c phase transition in partially amorphous (METAMICT) titanite revealed by Raman spectroscopy
JO  - The Canadian mineralogist
VL  - 52
IS  - 1
SN  - 1499-1276
CY  - Ottawa
PB  - Assoc.
M1  - PUBDB-2014-04231
M1  - BMBF-Projekt 05K13GU1
SP  - 91 - 100
PY  - 2014
N1  - (c) Mineralogical Association of Canada. Post referee fulltext in progress.
AB  - In situ temperature-dependent Raman spectroscopic measurements of two partially amorphous (metamict) titanite samples with accumulated radiation doses  1.2 × 1018 α-events/g (E2335) and  2.2 ×1018 α-events/g (M28696) and amorphous fractions of 0.24 and 0.5, respectively, provide evidence for a thermally induced transformation analogous to the phase transition P21/c ↔ C2/c, which is characteristic of endmember titanite (CaTiSiO5). Quantitative analysis of the temperature evolution of the wavenumbers and widths of Raman-active vibrations in both partially amorphous titanites reveals an anomaly near 500 K which is consistent with the P21/c ↔ C2/c phase-transition temperature of titanite close to its endmember composition. The observed spectral changes are not due to structural recovery of the radiation-damaged structure because synchrotron X-ray diffraction experiments of M28696 titanite show that relevant recrystallization occurs at annealing temperatures above 600 K. The structural transformation near 500 K is observed by Raman spectroscopy even in heavily radiation-damaged and chemically inhomogeneous titanite (M28696). The microstructure of the samples consists of coexisting crystalline and amorphous domains, with the P21/c to C2/c phase-transition occurring in the latter.
LB  - PUB:(DE-HGF)29 ; PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000336185600007
DO  - DOI:10.3749/canmin.52.1.91
UR  - https://bib-pubdb1.desy.de/record/192654
ER  -