Eu3+-Activated Borogermanate Scintillating Glass with a High Gd2O3 Content

Eu3+-activated borogermanate scintillating glasses with compositions of 25B2O340GeO225Gd2O3(10x)La2O3xEu2O3 were prepared by melt-quenching method. Their optical properties were studied by transmittance, photoluminescence, Fourier transform infrared (FTIR), Raman and X-ray excited luminescence (XEL) spectra in detail. The results suggest that the role of Gd2O3 is of significance for designing dense glass. Furthermore, energy-transfer efficiency from Gd3+ to Eu3+ ions can be near 100% when the content of Eu2O3 exceeds x=4, the corresponding critical distance for Gd3+Eu3+ ion pairs is estimated to be 4.57 angstrom. The strongest emission intensities of Eu3+ ions under both 276 and 394nm excitation are simultaneously at the content of 8mol% Eu2O3. The degree of EuO covalency and the local environment of Eu3+ ions are evaluated by the value of t parameters from JuddOfelt analysis. The calculated results imply that the covalency of EuO bond increases with the increasing concentration of Eu3+ ions in the investigated borogermanate glass. As a potential scintillating application, the strongest XEL intensity under X-ray excitation is found to be in the case of 6mol% Eu2O3, which is slightly different from the photoluminescence results. The possible reason may be attributed to the discrepancy of the excitation mechanism between the ultraviolet and X-ray energy.