Bulk nucleation and crystal growth in calcium tetra and digermanate glasses

Calcium tetragermanate and calcium digermanate glasses were prepared and studied with the aid of differential thermal analysis, X-ray diffraction and FTIR spectroscopy. The molar ratio of GeO 6 GeO 4 groups increases with the CaO GeO 2 molar ratio. A two steps crystallisation process was found: init...

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Bibliographic Details
Published in:Journal of the European Ceramic Society 1998, Vol.18 (11), p.1587-1591
Main Authors: Catauro, M., Laudisio, G.
Format: Article
Language:English
Subjects:
Cross-disciplinary physics: materials science
rheology
Exact sciences and technology
Growth from solid phases (including multiphase diffusion and recrystallization)
Materials science
Methods of crystal growth
physics of crystal growth
Physics
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Summary:Calcium tetragermanate and calcium digermanate glasses were prepared and studied with the aid of differential thermal analysis, X-ray diffraction and FTIR spectroscopy. The molar ratio of GeO 6 GeO 4 groups increases with the CaO GeO 2 molar ratio. A two steps crystallisation process was found: initially microcrystals are formed that at higher temperatures are transformed in well shaped crystals. An unidentified phase crystallises in both glasses. CaGe 2O 5 crystals also grow in calcium digermanate glass. The influence of the specific surface area of the glass sample and of a heat treatment of nucleation was pointed out. The activation energy for crystal growth in each glass was evaluated by a non isothermal method.
ISSN:0955-2219
1873-619X
DOI:10.1016/S0955-2219(98)00079-X