In this article upconversion luminescence of silver nanoparticles（AgNPs） coated NaYF4：Er3＋/Yb3＋phosphor nano-particles was investigated.The prepared samples were characterized through various techniques.The surfa...In this article upconversion luminescence of silver nanoparticles（AgNPs） coated NaYF4：Er3＋/Yb3＋phosphor nano-particles was investigated.The prepared samples were characterized through various techniques.The surface plasmon band is observed for prepared AgNPs by analyzing UV-vis measurements and is used to enhance the upconversion emission.From the upconversion measurement the emission bands are observed at 522,546,and 656 nm corresponding to the 2 H11/2→ 4115/2,4 S3/2→4 I15/2and 4 F9/2→4 I15/2 levels,respectively.The upconversion emission intensity of the above bands is found to enhance for sample containing 1 mmol AgNPs.Decay time of 4 S3/2 and 4F9/2 levels is found to decrease on coating of AgNPs and hence intensity enhancement is assumed due to the surface plasmon resonance（SPR） effect.展开更多
AlON：1.6 mol.%Er3＋, x mol.%Yb3＋（x=0, 2.6, 3.1, 3.6, 4.1, 4.6） phosphors were synthesized successfully by aluminothermic reduction and nitridation（ATRN） method and characterized by X-ray diffraction（XRD）, scan...AlON：1.6 mol.%Er3＋, x mol.%Yb3＋（x=0, 2.6, 3.1, 3.6, 4.1, 4.6） phosphors were synthesized successfully by aluminothermic reduction and nitridation（ATRN） method and characterized by X-ray diffraction（XRD）, scanning electron microscopy（FESEM） and upconversion photoluminescence（UCPL） emission spectra. Under the excitation of diode laser 980 nm, the green（556 nm） and red（655 nm） upconverted emissions were observed, attributed to the 4S3/2→4I15/2 and 4F9/2→4I15/2 transition of Er3＋respectively. The emission intensity increased with increasing Yb3＋ concentration due to the energy transfer（ET） between Yb3＋ and Er3＋. The upconverted emission reached the highest as x=3.6, and was pump-power dependent involving a two-photon process.展开更多
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
基金Project supported by the Indian Institute of Technology(Indian School of Mines),Dhanbad,Indiathe Council of Scientific&Industrial Research(CSIR),New Delhi,India(03(1303)13/EMR)
文摘In this article upconversion luminescence of silver nanoparticles（AgNPs） coated NaYF4：Er3＋/Yb3＋phosphor nano-particles was investigated.The prepared samples were characterized through various techniques.The surface plasmon band is observed for prepared AgNPs by analyzing UV-vis measurements and is used to enhance the upconversion emission.From the upconversion measurement the emission bands are observed at 522,546,and 656 nm corresponding to the 2 H11/2→ 4115/2,4 S3/2→4 I15/2and 4 F9/2→4 I15/2 levels,respectively.The upconversion emission intensity of the above bands is found to enhance for sample containing 1 mmol AgNPs.Decay time of 4 S3/2 and 4F9/2 levels is found to decrease on coating of AgNPs and hence intensity enhancement is assumed due to the surface plasmon resonance（SPR） effect.
基金Project supported by National Natural Science Foundation of China(91022035)"One Hundred Talent Project"the Natural Science Foundation of Fujian Province(2014H0055)
文摘AlON：1.6 mol.%Er3＋, x mol.%Yb3＋（x=0, 2.6, 3.1, 3.6, 4.1, 4.6） phosphors were synthesized successfully by aluminothermic reduction and nitridation（ATRN） method and characterized by X-ray diffraction（XRD）, scanning electron microscopy（FESEM） and upconversion photoluminescence（UCPL） emission spectra. Under the excitation of diode laser 980 nm, the green（556 nm） and red（655 nm） upconverted emissions were observed, attributed to the 4S3/2→4I15/2 and 4F9/2→4I15/2 transition of Er3＋respectively. The emission intensity increased with increasing Yb3＋ concentration due to the energy transfer（ET） between Yb3＋ and Er3＋. The upconverted emission reached the highest as x=3.6, and was pump-power dependent involving a two-photon process.
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.
