Photoluminescence and crystallization in europium-doped fluorobromozirconate glass-ceramics

We have investigated barium bromide crystallization in glasses which have a n overall composition of 53% ZrF4, 20% BaF2, 5% NaF, 15% NaBr, 1% LaF3, 3% AlF3, 2% YF3, and 1% EuF2. The glasses were prepared by melting at 850 degr eesC in an inert atmosphere and quenching into a brass mold. Subsequent the rmal treatment of the glass yields a transparent or translucent fluorozirco nate glass containing BaBr2 crystals; this glass-ceramic material has poten tial applications as an X-ray storage phosphor. The glasses and glass-ceram ics were investigated using photoluminescence, optical density, X-ray diffr action, and differential scanning calorimetry methods. Glasses which have b een quenched to temperatures below 260 degreesC are transparent and show no photoluminescence from the europium ions. When the glasses are subsequentl y heated above about 263 degreesC, crystals of BaBr2 in the hexagonal phase start to precipitate and photoluminescence from Eu2+ ions is observed. It is possible to prepare the resulting glass-ceramic in transparent form by h eating to temperatures just below the temperature of most rapid crystalliza tion, T-x = 280 C. The photoluminescence is attributed to Eu2+ ions replaci ng Ba2+ ions in the BaBr2 crystals. (C) 2001 Elsevier Science B.V. All righ ts reserved.