Photo- and radio-luminescence properties of 3CaO-2SiO2 and 3CaF2-2SiO2 glasses doped by Ce3+ ions

Wavelength-shifting materials in the form of optical fibers are requested in order to both convert UV scintillation light produced by fast scintillators into a more easily detectable visible light, and to efficiently transport it to the detectors.

In the present investigation we have considered glasses with composition 3CaO-2SiO₂ and 3CaF₂-2SiO₂ doped with 0.05, 0.5 and 1 at% of Ce3+ions, prepared by an original method consisting in a combination of co-precipitation and sol-gel approaches. The glasses have been investigated by Raman scattering, as well as by photo- and radio-luminescence.

The glasses are characterized by complex Raman features. Composite photo-luminescence excitation and emission spectra are also detected in all cases, depending upon glass composition and Ce concentration. Broad excitation spectra extend from approximately 260 nm to 360 nm, while the composite Ce3+ emission is detected in the blue spectral region at around 400 nm. A satisfactory matching between the excitation spectra of the glasses and the emission spectrum of CeF₃ scintillator occurs, confirming their potential application as wavelength shifters of CeF₃ UV scintillation light. Moreover, bright photo-luminescence signals are accompanied by a very poor radio-luminescence. The results are discussed by taking into account the presence of different silicate clusters embedded in the glass network, as well as the role of point defects in the radio-luminescence process.