Characterization of metamict minerals with complex crystalchemical properties – allanite example

Čobić, Andrea (2015) Characterization of metamict minerals with complex crystalchemical properties – allanite example. Doctoral thesis, Faculty of Science > Department of Geology.

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Abstract

Recrystallization of allanite with different degrees of metamictization is induced by annealing of samples in air, inert and reductive atmosphere at chosen temperatures. Up to 800°C metamict samples of allanite partially recrystallize to allanite crystal structure, but with heavily metamictized samples, already at these temperatures, new phases such as cerianite and hematite, occur. It is impossible to accomplish complete recrystallization in these conditions due to oxidation of Fe2+ and Ce3+, and escape of OH- anion from the structure, and at higher temperatures (> 900°C), allanite crystal structure breaks down to a mixture of simple oxides (cerianite an hematite), phosphate (britholite) and silicate (anorthite). Thus, chosen samples were hydrothermally treated at lower (150 -250°C), and higher (400-800°C) temperatures when complete recrystallization, without additional phases and regardless of the degree of metamictization, occurs. One allanite sample was bombarded with neutron flux, in order to destroy its crystal structure, what was partially accomplished. All processes were monitored by X-ray powder diffraction, high-resolution transmission electron microscopy coupled with electron diffraction, IR, Raman and Mössbauer spectroscopy, and thermal methods.

Item Type: Thesis (Doctoral thesis)
Keywords: allanite, complex crystal-chemical properties, metamictization, recrystallization
Supervisor: Bermanec, Vladimir
Date: 2015
Number of Pages: 193
Subjects: NATURAL SCIENCES > Geology > Mineralogy and Petrology
Divisions: Faculty of Science > Department of Geology
Depositing User: Danica Vujičić
Date Deposited: 01 Jul 2015 12:27
Last Modified: 01 Jul 2015 12:27
URI: http://digre.pmf.unizg.hr/id/eprint/4023

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