Comparative study of Sm3+ ions doped phosphate based oxide and oxy-fluoride glasses for solid state lighting applications

Abstract The physical and luminescent properties of Sm 3+ -doped oxide and oxy-fluoride phosphate glasses were investigated. The glass samples with chemical composition of 69P 2 O 5 -10BaO-10ZnO-10Gd 2 O 3 -1Sm 2 O 3 and 69P 2 O 5 -10BaO-10ZnO-10GdF 3 -1Sm 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, photoluminescence, 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 and1585 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 P 3/2 , 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-luminescence it is observed that the oxy-fluoride glass samples show better emission intensity than the oxide glass. The Judd-Ofelt theory (J-O 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.