Mechanisms of upconversion luminescence（UCL） of SrF2：Er phosphors corresponding to the 4G11∕2→4I15∕2,2H9∕2→4I15∕2,4F5∕2→4I15∕2,4F7∕2→4I15∕2,2H11∕2→4I15∕2,4S3∕2→4I15∕2,4F9∕2→4I15∕2, and 4I9∕2→...Mechanisms of upconversion luminescence（UCL） of SrF2：Er phosphors corresponding to the 4G11∕2→4I15∕2,2H9∕2→4I15∕2,4F5∕2→4I15∕2,4F7∕2→4I15∕2,2H11∕2→4I15∕2,4S3∕2→4I15∕2,4F9∕2→4I15∕2, and 4I9∕2→4I15∕2 transitions upon excitation of the 4I11∕2 level of Er3＋ions were investigated. Energy transfer upconversion processes are responsible for the populating of the 2H9∕2,2H11∕2,4S3∕2, and 4F9∕2 levels. Cooperative process is the dominant mechanism of luminescence from 4S3∕2 and 4F9∕2 levels for SrF2：Er with high concentrations of Er3＋ions. The UCL from 4G11∕2 and 4F5∕2 is explained by excited-state absorption. Cross-relaxation processes take part in the population of 4F9∕2 and 4I9∕2 levels. For quantifying material performance, the Er3＋-concentration dependence of UCL and the absolute quantum yields of SrF2：Er were studied. The most intensive visible luminescence was obtained for SrF2：Er（14.2%） with 0.28% maximum quantum yield.展开更多
Absolute quantum yield （Ф） is one of the most important parameters to evaluate the potential of novel materials. Lanthanide complexes EuxGd1-x（TTA）3phens are synthesized with the ratio of Gd3＋ dopant concentrati...Absolute quantum yield （Ф） is one of the most important parameters to evaluate the potential of novel materials. Lanthanide complexes EuxGd1-x（TTA）3phens are synthesized with the ratio of Gd3＋ dopant concentration ranging from 10% to 90% to improve the absolute quantum yield. EuxGd1-x（TTA）3phens possess similar infrared and ultraviolet spectra, showing that they have similar molecular structures. The absolute emission quantum yields of EuxGd1-x（TTA）3phens are determined using a fluoromax-4 spectrofluorometer equipped with an integrating sphere. The fluorescence lifetimes of the EuxGd1-x（TTA）3phens are measured in the same experiment. It was found that both absolute quantum yields and fluorescence lifetimes of EuxGd1-x（TTA）3phens are of quasi-periodic variation with the change of the Gd3. dopant concentrations. The absolute quantum efficiency and fluorescence lifetime vary with respect to the Gd content in an opposite fashion, indicating that the rate of energy absorption by the EuxGd1-x（TTA）3phens and the conversion to light energy is critical for the absolute quantum efficiency. The radiative rate constant Kr and non-radiative rate constant Knr are calculated. The dependence of Kr and Knr on the Gd3＋ dopant concentrations is very similar to that of absolute quantum efficiency. The radiation rate constant Kr and absolute quantum efficiency have a linear relationship.展开更多
基金supported by the Russian Science Foundation(No.17-72-10163)
文摘Mechanisms of upconversion luminescence（UCL） of SrF2：Er phosphors corresponding to the 4G11∕2→4I15∕2,2H9∕2→4I15∕2,4F5∕2→4I15∕2,4F7∕2→4I15∕2,2H11∕2→4I15∕2,4S3∕2→4I15∕2,4F9∕2→4I15∕2, and 4I9∕2→4I15∕2 transitions upon excitation of the 4I11∕2 level of Er3＋ions were investigated. Energy transfer upconversion processes are responsible for the populating of the 2H9∕2,2H11∕2,4S3∕2, and 4F9∕2 levels. Cooperative process is the dominant mechanism of luminescence from 4S3∕2 and 4F9∕2 levels for SrF2：Er with high concentrations of Er3＋ions. The UCL from 4G11∕2 and 4F5∕2 is explained by excited-state absorption. Cross-relaxation processes take part in the population of 4F9∕2 and 4I9∕2 levels. For quantifying material performance, the Er3＋-concentration dependence of UCL and the absolute quantum yields of SrF2：Er were studied. The most intensive visible luminescence was obtained for SrF2：Er（14.2%） with 0.28% maximum quantum yield.
基金supported by the National Natural Science Foundation of China(No.50973003)Anhui Science and TechnologyProgram(Nos.KJ2012B135,KJ2012A217,KJ2012B136,KJ2011A210, 1301042112)+1 种基金Natural Science Foundation of Fuyang Normal College (Nos.2011HJJC02ZD,2011HJJC01ZD,2011HJJC04YB,2010FSKJ01ZD, 2013FSKJ03ZD)Incubator Fund of Scientific and Technological achievements of Fuyang Normal College(Nos.2013KJFH03, 2013KJFH01)
文摘Absolute quantum yield （Ф） is one of the most important parameters to evaluate the potential of novel materials. Lanthanide complexes EuxGd1-x（TTA）3phens are synthesized with the ratio of Gd3＋ dopant concentration ranging from 10% to 90% to improve the absolute quantum yield. EuxGd1-x（TTA）3phens possess similar infrared and ultraviolet spectra, showing that they have similar molecular structures. The absolute emission quantum yields of EuxGd1-x（TTA）3phens are determined using a fluoromax-4 spectrofluorometer equipped with an integrating sphere. The fluorescence lifetimes of the EuxGd1-x（TTA）3phens are measured in the same experiment. It was found that both absolute quantum yields and fluorescence lifetimes of EuxGd1-x（TTA）3phens are of quasi-periodic variation with the change of the Gd3. dopant concentrations. The absolute quantum efficiency and fluorescence lifetime vary with respect to the Gd content in an opposite fashion, indicating that the rate of energy absorption by the EuxGd1-x（TTA）3phens and the conversion to light energy is critical for the absolute quantum efficiency. The radiative rate constant Kr and non-radiative rate constant Knr are calculated. The dependence of Kr and Knr on the Gd3＋ dopant concentrations is very similar to that of absolute quantum efficiency. The radiation rate constant Kr and absolute quantum efficiency have a linear relationship.
