%0 Journal Article
%A Beirau, T.
%A Mihailova, B.
%A Malcherek, T.
%A Paulmann, C.
%A Bismayer, U.
%A Groat, L. A.
%T Temperature-induced P21/c to C2/c phase transition in partially amorphous (METAMICT) titanite revealed by Raman spectroscopy
%J The Canadian mineralogist
%V 52
%N 1
%@ 1499-1276
%C Ottawa
%I Assoc.
%M PUBDB-2014-04231
%M BMBF-Projekt 05K13GU1
%P 91 - 100
%D 2014
%Z (c) Mineralogical Association of Canada. Post referee fulltext in progress.
%X 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.
%F PUB:(DE-HGF)29 ; PUB:(DE-HGF)16
%9 ReportJournal Article
%U <Go to ISI:>//WOS:000336185600007
%R 10.3749/canmin.52.1.91
%U https://bib-pubdb1.desy.de/record/192654