Title:	Optical Properties of Borate Glass-Ceramics
Authors:	Oprea, Isabella-Ioana
Thesis advisor:	apl. Prof. Dr. Klaus Betzler
Thesis referee:	Dr. Ekaterina Shamonina
Abstract:	Optical properties of bismuth borate are measured for the composition range x Bi2O3 (1-x) B2O3, 0.25 < x < 0.65. The refractive indices increase as the bismuth content is increasing. Also the ultraviolet absorption edge was shown to shift to longer wavelengths. From these measurements a generalized Sellmeier formula was derived. Applying heat treatments to the prepared bismuth borate glasses in order to obtain glass ceramics leads in most cases to surface nucleation. It was proved that dopants increase the number of nucleating sites on the surfaces. On erbium-doped samples absorption and luminescence measurements were made. The Judd-Ofelt analysis revealed comparably high Judd-Ofelt coefficients. All coefficients were shown to decrease as the Bi2O3 content increases. The luminescence at 1550 nm reveals a broad and flat band which is narrowing with the increase in Bi2O3 content. The green upconversion was observed and the temporal behavior of the emission at 550 nm was investigated. The absorption and emission spectra of chromium-doped bismuth borate glasses were measured. On surface crystallized glasses, for x = 0.5 Bi2O3 and high chromium content, luminescence of chromate (CrO2-4) ion doped BiBO3 microcrystals was observed. Strontium barium niobate microcrystals embedded in strontium barium borate matrix were obtained by spontaneous nucleation in the melt and rapid quenching. Optical properties of Pb2B5O9Br based glass were also investigated. The heat treatment applied leads to the formation of small nanocrystals inside the glass.
URL:	https://osnadocs.ub.uni-osnabrueck.de/handle/urn:nbn:de:gbv:700-2005020327
Subject Keywords:	Bismuth borate; glass; glass-ceramics; absorption; luminescence; refractive index; Erbium; Neodym; Chromium
Issue Date:	3-Feb-2005
Submission date:	3-Feb-2005
Type of publication:	Dissertation oder Habilitation [doctoralThesis]
Appears in Collections:	FB06 - E-Dissertationen

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