Regensburg 2010 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 39: Glasses and Glass Transition II (jointly with DY and DF)

CPP 39.8: Talk

Thursday, March 25, 2010, 11:30–11:45, H38

Crystallization and structural investigation of Eu-doped fluorozirconate-based glass ceramics. — •Christian Paßlick¹, Bernd Ahrens^1,2, Bastian Henke^1,2, Jacqueline A. Johnson³, and Stefan Schweizer^1,2 — ¹Centre for Innovation Competence SiLi-nano^®, Martin Luther University of Halle-Wittenberg, Karl-Freiherr-von-Fritsch-Str. 3, 06120 Halle (Saale) — ²Fraunhofer Center for Silicon Photovoltaics, Walter-Hülse-Str. 1, 06120 Halle (Saale) — ³Department of Materials Science and Engineering, University of Tennessee Space Institute, Tullahoma, TN 37388, USA

A series of Eu-doped fluorozirconate-based glass ceramics has been developed for medical and photovoltaic applications. In the first case, the materials can be used as x-ray scintillators or x-ray storage phosphors, in the latter case as down-converting top layers for highly efficient solar cells. The glasses are based on a modified ZBLAN composition, i.e. a mixture of Zr, Ba, La, Al, and Na fluorides. They are additionally doped with chlorine ions to initiate the growth of BaCl₂ nanocrystals upon thermal processing. Eu²⁺ ions are incorporated into the nanocrystals during the annealing procedure enabling a strong fluorescence upon ultraviolet or x-ray excitation. The nanocrystal size and structural phase depend significantly on the heating conditions and Eu doping level. X-ray diffraction patterns show a structural phase change of the BaCl₂ nanocrystals from hexagonal to orthorhombic as annealing temperatures are increased. DSC experiments were performed to obtain activation energies, thermal stability parameters and information on the crystal growth mechanisms.