Optical and luminescence characteristics of Eu^(3+)-doped B_2O_3:SiO_2:Y_2O_3:CaO glasses for visible red laser and scintillation material applications

Europium（Eu^3＋） doped glasses of chemical compositions（55-x）B2O3：10 SiO2：25 Y2O3：10CaO：xEu2O3,where x denotes mol% and ranges 0≤ x ≤ 2.5, were synthesized by adopting conventional melt quenching technique, Physical properties like density, molar volume, polaron radius, inter-ionic distance and field strength of the glass samples were investigated to assess the impact of Eu2O3. Optical and luminescence properties of the glasses were characterized with optical absorption, photoluminescence,X-ray induced emission spectra, temperature dependence emission spectra and decay times. Judd-Ofelt（JO） intensity parameters（Ωλ） of the glasses were evaluated based on the absorption spectrum of 0.5 mol%. JO parameters, calculated from absorption spectra with thermal corrections on oscillator strength, were used to evaluate radiative properties such as radiative transition probability（AR）,branching ratio（βR）, stimulated cross section emission（σ） and radiative lifetime（τR） for 5D0→7 FJ（J = 0,1,2,3 and 4） transitions. The decay rate of 5D0 fluorescent level for all the glass samples was single exponential. Lifetimes of the 5D0 level were decreased with increasing concentrations of Eu^3＋ions from 0.05 mol% to 2.5 mol% which might be due to energy transfer through cross-relaxation in the glasses. The chromaticity coordinates（x, y） were similar for all BSYCaEu glasses and were located at the red region of CIE 1931 color chromaticity diagram. Hence, these results confirm that the Eu^3＋ doped BSYCaEu glasses could be useful for visible red lasers and glass scintillation applications.

Comparative study of Sm^(3+) ions doped phosphate based oxide and oxy-fluoride glasses for solid state lighting applications

The physical and luminescent properties of Sm^(3+)-doped oxide and oxy-fluoride phosphate glasses were investigated. The glass samples with chemical composition of 69 P_2 O_5-10 BaO-10 ZnO-10 Gd_2 O_3-1 Sm_2 O_3 and 69 P_2 O_5-10 BaO-10 ZnO-10 GdF_3-1 Sm_2 O_3 were prepared by conventional melt quenching technique. The prepared glass samples were characterized with density, molar volume, refractive index,FTIR, UV-Vis-NIR, photo luminesce nce, radio luminescence, decay time profile and CIE diagram. The density and refractive index of the oxide glass have higher values as compared to the oxy-fluoride glass.The FTIR spectra show the reduction of O-H group in oxy-fluoride glass. The characteristic peaks of Sm^(3+)are observed at 360,372,402,438,419,473,944,1077,1227,1373,1474,1529 and 1585 nm in UV-VIS-NIR spectra. These peaks are related respectively to the transitions from ground state ~6 H_(5/2) to ~4 D_(3/2), ~6 P_(7/2),6 P3/2, ~4 I_(11/2), ~6 F_(11/2), ~6 F_(9/2), ~6 F_(7/2),~6 F_(5/2),~6 F_(3/2), ~6 H_(15/2) and ~6 F_(1/2) excited states. From photoluminescence and radio-luminesce nce it is observed that the oxy-fluoride glass samples show better emission intensity than the oxide glass. The Judd-Ofelt theory(J-0 theory) was used to find J-O intensity Ω_λ(λ = 2,4 and 6)parameters and radiative properties such as transition probability, stimulated emission cross section and branching ratios for titled glasses. The trend observed in the J-O parameters is Ω_4 >Ω_2 >Ω_6. The transition probability,emission cross section and branching ratio have the highest values for the ~4 G_(5/2)→~6 H_(7/2)transition. The CIE coordinates of the prepared glass samples are positioned in the orange region and the CCT value is 3776.105 for oxide and oxyfluoride glass. The oxy-fluoride glass has shorter decay time as compared to the oxide glass and it is recorded to be 1.62 and 1.32 ms for oxide and oxy-fluoride respectively. According to the results obtained in this work, it is obvious that these glass samples can be good candidate materials for producing cool orange light.