Phase Separation and Fluorescence Properties of Rare-Earth Doped Borosilicate Glasses
Final Report Abstract
Within the project, Tb-doped borosilicate glasses were investigated, which show phase separation into a borate-rich droplet phase surrounded by a silicate-rich matrix. The phase separation structures were microstructurally characterized in terms of their shape, size, and size distribution using high-resolution TEM analyses. Special focus lay on the determination of the local distribution of the Tb ions. It turned out that Tb diffuses preferentially into the borate-rich droplets during the phase separation process and that even low dopant concentrations result in a cluster formation of the rare earth ions. At higher Tb concentrations, larger Tb particles are present in the silicate-rich matrix. The correlation of the microstructure results with stationary and time-resolved fluorescence spectroscopy measurements shows that a quenching of the fluorescence can only be observed when the number of Tb particles in the matrix is comparatively high. This leads to a clear decrease in the fluorescence intensities of the glasses and an additional fluorescence component with a very short fluorescence lifetime. Furthermore, it has been shown that fluorescence lifetime measurements are not sensitive enough to detect early clustering. Hence, a combination of nano- or microstructure diagnostics and fluorescence investigations is advantageous. With the help of NMR investigations on Tb- and Scdoped glasses as well as glasses that do not exhibit phase separation, it was possible to prove that the Tb ions are coordinated by borate groups, with B4-groups in the first coordination sphere. The substitution of Na2O by other alkali or alkaline earth oxides or a combination thereof results in spinodal phase separation. An increase in the amount of non-bridging oxygens and thus of the optical basicity causes the appearance of fluorescence bands in the blue region. In addition, a broadening of the green emission peaks and the splitting of the main peak is observed.
Publications
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Phase separation and fluorescence properties of rare-earth doped borosilicate glasses, 25th International Congress on Glass (ICG) 2019, Boston
K. Thieme; C. Patzig; C. Rüssel & T. Höche
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Clustering and phase separation in borosilicate glasses 94th Annual Meeting of the German Society of Glass Technology (DGG) 2021, Offenbach, videoconference
K. Thieme; C. Patzig & T. Höche
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Clustering in Tb-doped borosilicate glasses – A combined TEM, fluorescence spectroscopy, and NMR study, 26th International Congress on Glass (ICG) 2022, Berlin
K. Thieme; U. Rehfuß; C. Patzig; L. van Wüllen & T. Höche
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Early-stage clustering in Tb-doped borosilicate glasses revealed by high-resolution scanning transmission electron microscopy and luminescence properties. Journal of Alloys and Compounds, 962, 171091.
Thieme, Katrin; Patzig, Christian; Topper, Brian; Thieme, Christian; Gierth, Stephan; Rüssel, Christian & Höche, Thomas
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Early-stage clustering in Tbdoped borosilicate glasses revealed by high-resolution scanning transmission electron microscopy, Glass & Optical Materials Division Annual Meeting (GOMD) 2023, New Orleans
K. Thieme; U. Rehfuß; C. Patzig; L. van Wüllen & T. Höche
