Structural evolution of CaF2 nanoparticles during the photoinduced crystallization of a Na2O–K2O–CaO–CaF2–Al2O3–ZnO–SiO2 glass
A glass in the system Na 2 O–SiO 2 –Al 2 O 3 –K 2 O–CaO–CaF 2 –ZnO was doped with Ce, Ag, Sn, Sb and Br. Homogeneous and transparent glass ceramics are obtained from this glass by the precipitation of CaF 2 nanoparticles. An interface-controlled crystallization mechanism hinders crystal growth after...
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Veröffentlicht in: | Journal of materials science 2017-12, Vol.52 (23), p.13390-13401 |
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Hauptverfasser: | , , , , , , |
Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | A glass in the system Na
2
O–SiO
2
–Al
2
O
3
–K
2
O–CaO–CaF
2
–ZnO was doped with Ce, Ag, Sn, Sb and Br. Homogeneous and transparent glass ceramics are obtained from this glass by the precipitation of CaF
2
nanoparticles. An interface-controlled crystallization mechanism hinders crystal growth after some time. By adding photosensitive agents, a tailored photoinduced CaF
2
crystallization was achieved. Structural evolution during irradiation and heat treatment was investigated by different electron microscopic techniques, e.g., scanning transmission electron microscopy (STEM) including energy-dispersive X-ray analysis (EDXS) and scanning electron microscopy (SEM) including electron backscatter diffraction (EBSD). Agglomerated structures with a size of ca. 35 nm were observed after the first thermal treatment at 530 °C. The Ag nucleation is accompanied by clustering of several components within the glass. CaF
2
particles with diameters of ca. 300 nm with a spherulitic structure are observed in the glass ceramic after the second heat treatment step at 560 °C. Calcium and fluoride are depleted from the glass matrix during crystallization, while SiO
2
is enriched. From (S)TEM micrographs, supplemented by selected area diffraction (SAD), outward growth of CaF
2
from a central point is observed. STEM–EDXS analyses show residual glass within the spherulitic structure. |
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ISSN: | 0022-2461 1573-4803 |
DOI: | 10.1007/s10853-017-1443-5 |