Highlights The photo-luminescence and scintillation properties of binary Li2O-2SiO2 glasses doped with Ce 3+ and Tb 3+ were investigated;  Li2O-2SiO2 glasses doped with Tb 3+ showed scintillation light yield up to 31000 ph/MeV. AbstractPhoto-and radioluminescent properties of lithium silicate glasses doped with Ce 3+ and Tb 3+ ions were evaluated. Glasses doped with Ce 3+ ions exhibit a shift of radioluminescence to photo-luminescence band. This effect was explained by a distribution of the crystal field strength in the activator sites, what results in the competition between different types of Ce 3+ ions in absorbing excitation energy from the matrix and limits a light yield of the Ce 3+ doped glass. We also investigated the possibility to use Tb 3+ ion instead of Ce 3+ as an alternative activator for a glass doping. Spin-orbit interaction plays a major role in the formation of electronic terms in Tb 3+ , where as an effect of the crystal field is small enough to form a distribution of emitting centers. Tb 3+ -doped samples demonstrate light yields up to 31000 ph/MeV with the concentration quenching starting at the levels of 10 at %. We also studied the effect of luminescence sensitization of Tb 3+ ions by Ce 3+ in the glasses co-doped with Ce 3+ and Tb 3+ . IntroductionCe 3+ -doped binary oxide glasses and glass ceramics containing metal oxides and silica were found to be suitable matrices for the preparation of scintillating materials [1-3]. They have crystalline structure what allows for additional improvement of the material properties. By introducing fluorine in the ligands and varying the content of metal oxide in the final composition one can obtain luminescent materials with various properties: high light yield of both scintillation and photoluminescence, or quenched scintillation and highly efficient photoluminescence [4]. Among such materials, Ce 3+ -doped Li2O-SiO2 glass [5-8] is one of the most widely used scintillation materials for thermal neutron detection.

The valence state of cerium and titanium ions in barium-strontium aluminosilicate glass with a different ratio of cerium and titanium oxides was investigated and the possible composition of the cerium-titanium complexes formed in silicate glass was analyzed. It was found that an active separate reaction between cerium and titanium oxides with the appearance of complex color centers takes place in synthesis of the glass. It is hypothesized that color centers primarily form between tetravalent cerium and tetravalent titanium in glass-forming melts.

UDC 666.175.6;621.794.5;535.37 Silicate glasses doped with ceria and titania have been studied. Such co-doping determines the specific coloration of the glasses with adjustable absorption in the visible spectral region. Based on measurements of optical transmittance and photoluminescence and studies of electron paramagnetic resonance, it was established that the features of their optical properties are due to the formation of chromophore centers incorporating cerium and titanium ions.Introduction. Optical materials containing transition and rare-earth ions are widely used in optics and quantum electronics to fabricate laser glasses that are stable to the action of UV radiation and to develop thermally stable light filters, etc. Interest in the use of Ce and Ti compounds in optical materials grew because of their use to prepare yellowish-orange glasses with consistent optical characteristics and high thermal stability [1]. Such glasses are used to fabricate various items for household and technical purposes and to imitate precious stones. It is important to establish the nature of the coloring effect and the valence and coordination state of the Ce and Ti ions in glasses used as filters for light emitters in the electrical industry because the optical characteristics must be controlled and stabilized.Optical properties of glasses with both Ce and Ti oxides present in various proportions (silicate, phosphate, borate glasses and thin films) have been studied several times [2][3][4]. However, there are significant discrepancies in the explanation of the nature of the coloring and the determination of the valence state of the Ce and Ti ions in the glass matrix. According to one study [2], compounds such as Ce(TiO 3 ) 2 and Ce(Ti 2 O 5 ) 2 with tetravalent Ce and Ti are formed. Another study [3] explains the yellow color by the effect of Ce and Ti ions on the total optical absorption. Yet another study [4] linked the appearance of the characteristic yellowish-orange color in silicate glasses with Ce and Ti to the formation of colored complexes between Ce 3+ and Ti 4+ ions. The involvement of both CeO 2 and TiO 2 in

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