Effect of zinc substitution for calcium on the crystallisation of calcium fluoro-alumino-silicate glasses

Abstract

A series of 25, 60, 75 and 100 mol% zinc substituted for calcium ionomer glasses of the composition 4.5SiO 2 -3Al 2 O 3 -1.5P 2 O 5 -3CaO-2CaF 2 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 characterised 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 crystallisation 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 SiF 4 was suggested. SEM and EDX analysis showed significant changes in the morphology of glass ceramics with zinc substitution. The formation of gahnite during glass crystallisation may open new application avenues for these materials in the field of semiconducting materials.

Comprehensive Study on Elastic Moduli Prediction and Correlation of Glass and Glass Ceramic Derived from Waste Rice Husk

“…Increase in density is largely due to substituting Si (28.08) with a higher atomic mass element of zinc which is (65.39). Besides, the increase in density with the increase of ZnO content occurs due to the increase in the crystallinity in the samples in which sample S1 is fully amorphous and sample S4 provides higher amounts of crystalline compared to the other samples [17,18]. Increase in crystallinity is due to the increase in melting point of the ZnO-SiO 2 samples as its melting point increases as ZnO in the system increases as shown in Figure 2.…”

New calcium‐free Na2O–Al2O3–P2O5 bioactive glasses with potential applications in bone tissue engineering

“…Due to the similarities in chemical composition of NAP10 phosphate glass and HAp, NAP10 exhibits the above mentioned bands even prior to incubation in SBF, but their intensities are completely different in comparison to HAp powder and NAP10 after incubation in SBF (with a HAp layer formed at the surface). Furthermore, only NAP10 prior to incubation shows a band at 660 cm −1 , which can be assigned to Al–O stretching vibrations …”

“…Furthermore, only NAP10 prior to incubation shows a band at 660 cm À1 , which can be assigned to Al-O stretching vibrations. 51 Tripathi et al suggest that the presence of Al 2 O 3 up to only 1.5 mol% increases bioactivity in the Li 2 O-CaO-Al 2 O 3 -P 2 O 5 -SiO 2 system. 52 In the CaO-Na 2 O-P 2 O 5 -Al 2 O 3 system, bioactivity does not decrease up to 2 mol%.…”

The effect of boron substitution for aluminium on the microstructure of calcium fluoro-aluminosilicate glasses and glass-ceramics

“…A N U S C R I P T glass melt was then water quenched to prevent phase separation and crystallisation. All of the glasses were finally milled using a gyro mill to very fine particles (<45 μm) [13].…”