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

The physical and luminescent properties of Sm3+-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 Sm3+ 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 H-6(5/2) to D-4(3/2), P-6(7/2), P-6(3/2), I-4(11/2), F-6(11/2), F-6(9/2), F-6(7/2), F-6(5/2), F-6(3/2), H-6(15/2) and F-6(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 Omega(lambda) (lambda = 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 Omega(4) > Omega(2) > Omega(6). The transition probability, emission cross section and branching ratio have the highest values for the (4)G(5/2) -> H-6(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. (C) 2019 Published by Elsevier B.V. on behalf of Chinese Society of Rare Earths.