The conversion of high energy radiation to visible light by luminescent ceramics

The properties of luminescence ceramics which are roughly based on rare-earth doped oxides, oxysulfides, garnets, and silicates have been investigated. The characteristic luminescence data of the ceramics considered, such as emission spectra and decay, are similar to those of corresponding powders or single crystals. However, conversion efficiency, afterflow, and energy resolution are strongly affected by ceramic processing due to its influence on the microstructure, final optical quality, and defect structure. In this connection residual pores and grain boundaries play an important role. For example, the insufficient optical quality of Gd₂O₂Sr:Pr,Ce-ceramics is the main reason not only for a reduced light output but also for a rather pronounced degradation of the energy resolution, beyond the merely statistical limit. Consequently, luminescent ceramics, at least in their present form, appear not be suited for spectrometric applications. In the case of scintillation counting, the presented ceramics exhibit rather high decay constants giving low count rates. This drawback can be improved by using activator dopants with faster optical transition