Effect of zinc substitution for calcium on the crystallisation of calcium fluoro-alumino-silicate glasses
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Colleges, School and Institutes
A series of 25, 60, 75 and 100 mol% zinc substituted for calcium ionomer glasses of the composition 4.5SiO2-3Al2O3-1.5P2O5-3CaO-2CaF2 were produced following a well-established melt quench route. Similar glass compositions have been widely used in dentistry as the glass component in glass ionomer cements. The glasses crystallise to an apatite and mullite phase after appropriate heat treatments and are interesting materials for bone repair. Zinc is a bactericidal agent and has shown ability to stimulate osteogenesis. The new zinc containing glass compositions were characterized by Helium Pycnometer, DSC, TGA, SEM and EDX. The density of the zinc substituted glasses and glass-ceramics increased with increasing the zinc content as expected. The glass transition temperature decreased with zinc substitution, whereas the crystallization temperature increased with zinc substitution. Zinc substituted glasses lead to the formation of gahnite in expense of mullite. Fluorapatite formation was not favoured in high zinc content glass ceramics, whereas loss of fluorine in the form of SiF4 was suggested. SEM and EDX analysis showed significant changes in the morphology of glass ceramics with zinc substitution. The formation of gahnite during glass crystallization may open new application avenues for these materials in the field of semiconducting materials.
|Journal||Journal of Non-Crystalline Solids|
|Early online date||23 Oct 2015|
|Publication status||Published - 15 Jan 2016|
- fluoro-alumino-silicate glass, crystal phases, gahnite