X-ray excited luminescence and photoluminescence of Bi4(GeO4)3 glass-ceramics
Introduction
An alternative to the well-known crystalline detectors such as NaI:Tl, CsI:Na, Bi4(GeO4)3 (BGO), CsWO4 (for a review see (van Eijk et al., 1994)) are the glassy scintillators (Fu et al., 2003) since it may be possible to exploit the advantages of the light-guiding properties of glass to improve the light collection in the read-out system and of their relatively easy manufacturing in different shapes and forms.
The aim of this paper is the characterization of the BGO glass and especially glass-ceramic materials as scintillators for low energy electron beam and X-ray excitations. Further we briefly discuss the defects induced by these radiations.
Section snippets
Sampling
Mixtures of 40% Bi2O3 and 60% GeO2 (molar percent) were prepared wet-mixed in acetone, dried at 100 °C for 24 h and transferred to an Al2O3 crucible, before heating at 700 °C for 24 h. The resulting powder was subsequently heated to 1050 °C for 5–10 min. The resulting melts were poured onto preheated graphite plates at different temperatures, followed by slowly cooling in air to room temperature.
For thermoluminescence (TL) measurements, the glass samples were milled in order to compare the results
Results and discussion
The resulting glass samples were reddish in color. Glass-ceramics were obtained after subsequently annealing above the crystallization temperature of about 558 °C as determined from differential thermal analysis (DTA) measurements (Polosan, 2009). The transparency of the samples decreases during annealing because polycrystalline structures cause milkiness. The X-ray diffraction (XRD) measurements on the initial glass showed that it is completely amorphous without crystallization peaks. However,
Conclusion
We conclude that, after annealing the BGO glass, a crystalline phase precipitates in the glass matrix and the properties of the new glass-ceramic are similar to those of BGO crystal. X-ray luminescence confirms the efficiency of glass-ceramic materials compared to BGO crystals, suggesting potentially scintillation properties of crystallized samples.
Acknowledgments
The authors gratefully acknowledge the financial support of the Romanian Ministry of Education and Research (PN II Project 71-007/2007).
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