Berlin 2001 – wissenschaftliches Programm

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CPP: Chemische Physik und Polymerphysik

CPP 15: Nanostructures

CPP 15.3: Vortrag

Donnerstag, 5. April 2001, 18:25–18:45, 112

Glass ceramics as X-ray storage phosphors with high spatial resolution — •Stefan Schweizer¹, Andrew Edgar², Mihail Secu¹, and Johann-Martin Spaeth¹ — ¹Department of Physics, University of Paderborn, 33095 Paderborn, Germany — ²School of Chemical and Physical Sciences, Victoria University, Wellington, New Zealand

The information storage in X-ray storage phosphor screens occurs via room-temperature-stable electron and hole trap centres. Upon photostimulation of the electron trap centres, the electron recombines with the hole resulting in a luminescence from a doped activator (PSL) which is usually a rare-earth ion. However, a continuing difficulty is that such powder-based screens show considerable scattering of the read-out light, limiting the spatial resolution. One possible solution to this scattering problem would be a phosphor based on a glass. For this purpose fluoride glasses were investigated. We found a significant PSL effect in Eu²⁺-doped fluorozirconate glasses (ZBLAN) which were additionally doped with Br⁻ ions [1]. The PSL is tentatively attributed to the 5d-4f emission of Eu²⁺ present in nano-crystallites of BaBr₂ which form in the glass on cooling and/or annealing. The PSL properties of the Eu²⁺-doped BaBr₂ nano-crystallites are compared to those of bulk BaBr₂ single crystals, and the location of the PSL-active electron and hole trap centres in the glass ceramic is discussed.

[1] A. Edgar, J.-M. Spaeth, S. Schweizer, S. Assmann, P. J. Newman, and D. R. Macfarlane, Appl. Phys. Lett. 75, 2386 (1999)