Glass Reflections
Cambridge 7th to 9th September
Presenting Author:
Delia Brauer
<delia.brauer@uni-jena.de>
article posted 16 Mar 2015
DeliaBrauer
Delia S. Brauer is a junior professor at the Otto Schott Institute, University of Jena,
Germany. After finishing her studies in environmental chemistry she completed her
PhD on phosphate glasses at the University of Jena. She worked as a postdoctoral
researcher at the University of California, San Francisco, Nagoya Institute of Technology,
Japan, and Imperial College London and Queen Mary University of London, UK,
before returning to Jena in 2012. Her research focuses on the structure-property
relationship in glasses, with a focus on degradable and highly disrupted glass systems
including phosphate glasses and bioactive glasses. She is a member of Technical
Committee 04 (Bioglasses) of the International Commission on Glass and Associate
Editor of a new journal "Biomedical Glasses".
Crystallization of Er3+:BaGdF5 from aluminosilicate glasses
Maxi Tylkowski1, Andreas Herrmann1,
Marcin Sroda2, Delia.S. Brauer1,*
Rare earth-doped materials gain more and more importance for modern applications in
lighting technology, communication and solid-state lasers. Over the last years, rare
earth-doped fluoride crystals within an aluminosilicate glass matrix have gained much
interest, as they combine the benefits of fluoride crystals (e.g. low phonon energy) with
the thermal and chemical stability of aluminosilicate glasses. Most of these glasses,
however, have very high melting temperatures (around 1600°C), which is a disadvantage
for commercialisation. The aim of this study was therefore to prepare fluoride-containing
aluminosilicate glasses of lower melting temperature and investigate their thermal
properties and crystallisation.
Glasses in the system SiO
2-Al
2O
3
-Al
2F
6-Gd
2O
3
-NaF-BaF
2 with 55mol% SiO
2 were
melted at 1400 to 1450°C and doped with Er
3+ ions at a concentration
of 5x10
19 cm
-3.
After DTA and dilatometry measurements, glasses were heat-treated between Tg
(about 580°C) and 750°C to analyse the formation of crystal phases.
All glasses were obtained transparent, although electron microscopy showed phase
separation in some of the glasses. Heat-treatment led to crystallization of barium
gadolinium fluoride phases, which are known for their low phonon energy and support
for energy transfer processes, which is important for applications using up- and
down-conversion processes. The obtained phases were BaGdF
5
and NaBa
5Gd
4F
23,
and morphology and growth mechanism of those phases were investigated using
SEM and TEM. At high temperatures, crystallisation of the silicate matrix occurred
as well. SEM microanalysis and fluorescence behaviour further showed that Er
3+
ions were successfully incorporated into the fluoride phases, which makes these
glass-ceramics of interest for applications as solid-state lasers or optical amplifiers.
Institutions:
1 Otto Schott Institute of Materials Research, Faculty of Chemistry and Earth Sciences,
Friedrich Schiller University, Jena, Germany
2 AGH-University of Science and Technology, Krakow, Poland