利用溶胶-凝胶法合成不同Er3+掺杂量的TiO2光催化材料,考察了Er3+掺杂量(0%~1%)、焙烧温度(400~700℃)和焙烧时间(1~4 h)对TiO2光催化材料对亚甲基蓝溶液的降解率、物相组成和光催化性能的影响。研究结果表明,Er3+掺杂TiO2光催化材料的...利用溶胶-凝胶法合成不同Er3+掺杂量的TiO2光催化材料,考察了Er3+掺杂量(0%~1%)、焙烧温度(400~700℃)和焙烧时间(1~4 h)对TiO2光催化材料对亚甲基蓝溶液的降解率、物相组成和光催化性能的影响。研究结果表明,Er3+掺杂TiO2光催化材料的最优制备工艺为:Er3+掺杂量为0.5%、焙烧温度为500℃、焙烧时间为2 h。随着Er3+掺杂量的增加,光催化材料的晶粒尺寸不断减小;Er3+掺杂的光催化材料的平均晶粒尺寸会随着焙烧温度的升高而逐渐减小;在焙烧温度为500℃时,焙烧时间的延长不会造成光催化材料中TiO2相的晶型转变,但TiO2晶体的晶粒尺寸会不断长大。Er3+掺杂量为0%、0.5%和1%的光催化材料的禁带宽度分别为2.76、2.0 e V和2.47 e V,Er3+掺杂量为0.5%时光催化材料的禁带宽度最小,具有最高的光吸收范围。展开更多
Gd2O3:Er^3+nanophosphors were fabricated by the combustion method in presence of Na2 ethylene diamine tetra acetic acid(EDTA-Na2)as fuel at not high temperature(≤350℃)within a very short time of 5 min.The added conc...Gd2O3:Er^3+nanophosphors were fabricated by the combustion method in presence of Na2 ethylene diamine tetra acetic acid(EDTA-Na2)as fuel at not high temperature(≤350℃)within a very short time of 5 min.The added concentration of Er^3+ions in Gd2O3 matrix was changed from 0.5 mol%to 5.0 mol%.The X-ray diffraction pattern of samples indicates the monoclinic structure of Gd2O3:Er^3+.The morphology and chemical composition analysis of the Gd2O3:Er^3+samples are characterized by a field emission scanning electron microscope(FESEM)and a Fourier-transform infrared spectrometer(FTIR).The photoluminescence(PL),photo luminescence excitation(PLE)and upconversion(UC)at room temperature of the prepared materials with different concentrations of Er^3+were investigated.The PL of Gd2O3:Er^3+nanomaterials are shown in visible at 545,594,623,648,688 nm under excitation at 275 nm.The emission bands from transitions of Er^3+from 2P3/2 to 4F9/2 are observed,UC luminescent spectra of the Gd2O3:Er^3+/silica nanocomposites under 976 nm excitation show the bands at 548 and 670 nm.The influence of excitation power at 980 nm for transitions were measured and calculated.The results indicate that the upconversion process of Gd2O3:Er^3+/silica is two photons absorption mechanism.The low temperature dependence of UC luminescent intensities of the main bands of Gd2O3:Er^3+was investigated towards development of a nanotemperature sensor in the range of 10-300 K.展开更多
In this study,the upconversion(UC)emissions of Er3+and Yb3+co-doped SrZrO3 nanocrystals(NCs)were investigated in terms of the thermal annealing temperature and concentration of Er3+ions and compared with the emissions...In this study,the upconversion(UC)emissions of Er3+and Yb3+co-doped SrZrO3 nanocrystals(NCs)were investigated in terms of the thermal annealing temperature and concentration of Er3+ions and compared with the emissions under a near-ultraviolet(near-UV)excitation.The NCs were synthesized by the combustion method,and the as-synthesized NCs were post-annealed at high temperatures.The X-ray diffraction patterns revealed that the grain sizes and crystallinity degrees of the samples increased with increasing annealing temperatures.The photoluminescence spectra of our samples exhibited strong green and very weak red emissions with the near-UV excitation,originating from the f-f transitions in the Er3+ions.Interestingly,under near-infrared(near-IR)excitation,we identified sizable visible emissions at 525,547,and 660 nm in our NCs,which indicated that the UC process successfully occurred in our NCs.These UC emissions were maximized in the NCs with an Er3+concentration of 0.02 and thermal annealing at 1000°C.We found that the intensity ratios of red to green emissions increased with increasing annealing temperatures.We discussed the differences in the emissions between near-UV and near-IR excitations.展开更多
Exploring a new tuning way to facilely realize single-band red emission in trivalent rare-earth ions(RE3+) doped upconversion(UC) materials is still desirable.In this work,the intense single-band red emission is achie...Exploring a new tuning way to facilely realize single-band red emission in trivalent rare-earth ions(RE3+) doped upconversion(UC) materials is still desirable.In this work,the intense single-band red emission is achieved by co-doping only Ho3+in the BiOCl:Er3+ under 1550 nm excitation.In the BiOCl layered host,co-doping Ho3+can further enhance the red emission and simultaneously suppress the green emission of Er3+,and thus obviously improve the red-to-green(R/G) ratio.It is found that Ho3+does not se rve as ene rgy trapping through the 5 I6 state as in traditional UC materials but acts as ET bridge(4 S3/2,2 H11/2(Er3+)→5 F4,5 S2(Ho3+)→4 F9/2(Er3+)).The tuning mechanism of Ho3+is discussed in detail and further confirms through a comparative experiment.Our research gives an unusual perspective to tune the UC behavior of Er3+through co-doping Ho3+,which might be inspiring for achievement of single-band red UC emission.展开更多
Yb3＋ and Er3＋ ions co-doped NaYF4 nanocrystals were synthesized with different amounts of NaOH via oleic acid（OA）-assisted hydrothermal process. X-ray diffraction（XRD）, scanning electron microscopy（SEM）, trans...Yb3＋ and Er3＋ ions co-doped NaYF4 nanocrystals were synthesized with different amounts of NaOH via oleic acid（OA）-assisted hydrothermal process. X-ray diffraction（XRD）, scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, Fourier transform infrared spectroscopy（FTIR）, and photoluminescence spectra were used to characterize the products. The result indicated that the introduction of Na OH into the initial reaction solution effectively promoted the cubic（α-） to hexagonal（β-） phase transition of NaYF4：Yb3＋,Er3＋ nanocrystals, while excessive amount of Na OH favored the formation of α-NaYF4：Yb3＋,Er3＋ nanocrystals. Besides, with the increase of Na OH amount, the morphologies of β-NaYF4：Yb3＋,Er3＋ nanocrystals varied from irregular nanobranch to uniform nanorod. Further investigation revealed that the addition of Na OH could facilitate the deprotonation of OA, leading to the formation of oleate（OA–）, and meanwhile increased the concentration of OH– ions, inducing consequently the phase transition and morphology evolution of NaYF4：Yb3＋,Er3＋ nanocrystals. Moreover, the upconversion luminescence properties of NaYF4：Yb3＋,Er3＋ nanocrystals were systematically investigated. It was found that the upconversion emissions not only depended on the phase and morphology but also were influenced by the surface groups.展开更多
文摘利用溶胶-凝胶法合成不同Er3+掺杂量的TiO2光催化材料,考察了Er3+掺杂量(0%~1%)、焙烧温度(400~700℃)和焙烧时间(1~4 h)对TiO2光催化材料对亚甲基蓝溶液的降解率、物相组成和光催化性能的影响。研究结果表明,Er3+掺杂TiO2光催化材料的最优制备工艺为:Er3+掺杂量为0.5%、焙烧温度为500℃、焙烧时间为2 h。随着Er3+掺杂量的增加,光催化材料的晶粒尺寸不断减小;Er3+掺杂的光催化材料的平均晶粒尺寸会随着焙烧温度的升高而逐渐减小;在焙烧温度为500℃时,焙烧时间的延长不会造成光催化材料中TiO2相的晶型转变,但TiO2晶体的晶粒尺寸会不断长大。Er3+掺杂量为0%、0.5%和1%的光催化材料的禁带宽度分别为2.76、2.0 e V和2.47 e V,Er3+掺杂量为0.5%时光催化材料的禁带宽度最小,具有最高的光吸收范围。
基金Project supported by the Vietnam National Foundation for Science and Technology Development(NAFOSTED)(103.03-2015.85)
文摘Gd2O3:Er^3+nanophosphors were fabricated by the combustion method in presence of Na2 ethylene diamine tetra acetic acid(EDTA-Na2)as fuel at not high temperature(≤350℃)within a very short time of 5 min.The added concentration of Er^3+ions in Gd2O3 matrix was changed from 0.5 mol%to 5.0 mol%.The X-ray diffraction pattern of samples indicates the monoclinic structure of Gd2O3:Er^3+.The morphology and chemical composition analysis of the Gd2O3:Er^3+samples are characterized by a field emission scanning electron microscope(FESEM)and a Fourier-transform infrared spectrometer(FTIR).The photoluminescence(PL),photo luminescence excitation(PLE)and upconversion(UC)at room temperature of the prepared materials with different concentrations of Er^3+were investigated.The PL of Gd2O3:Er^3+nanomaterials are shown in visible at 545,594,623,648,688 nm under excitation at 275 nm.The emission bands from transitions of Er^3+from 2P3/2 to 4F9/2 are observed,UC luminescent spectra of the Gd2O3:Er^3+/silica nanocomposites under 976 nm excitation show the bands at 548 and 670 nm.The influence of excitation power at 980 nm for transitions were measured and calculated.The results indicate that the upconversion process of Gd2O3:Er^3+/silica is two photons absorption mechanism.The low temperature dependence of UC luminescent intensities of the main bands of Gd2O3:Er^3+was investigated towards development of a nanotemperature sensor in the range of 10-300 K.
基金National Science Foundation of China(11004021,10804015)Fundamental Research Funds for the Central Universities(DC10040122,DC10020121)+1 种基金China Postdoctoral Science Foundation(2011M500623)Scientific and Technology Foundation of Dalian(2011J21DW021)
基金This research was supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF),funded by the Ministry of Science,ICT,and Future Planning(NRF-2018R1D1A1A02086130).
文摘In this study,the upconversion(UC)emissions of Er3+and Yb3+co-doped SrZrO3 nanocrystals(NCs)were investigated in terms of the thermal annealing temperature and concentration of Er3+ions and compared with the emissions under a near-ultraviolet(near-UV)excitation.The NCs were synthesized by the combustion method,and the as-synthesized NCs were post-annealed at high temperatures.The X-ray diffraction patterns revealed that the grain sizes and crystallinity degrees of the samples increased with increasing annealing temperatures.The photoluminescence spectra of our samples exhibited strong green and very weak red emissions with the near-UV excitation,originating from the f-f transitions in the Er3+ions.Interestingly,under near-infrared(near-IR)excitation,we identified sizable visible emissions at 525,547,and 660 nm in our NCs,which indicated that the UC process successfully occurred in our NCs.These UC emissions were maximized in the NCs with an Er3+concentration of 0.02 and thermal annealing at 1000°C.We found that the intensity ratios of red to green emissions increased with increasing annealing temperatures.We discussed the differences in the emissions between near-UV and near-IR excitations.
基金the National Natural Science Foundation of China(11874186)the Applied Basic Research Program of Yunnan Province(2017FB079)+1 种基金the Reserve Talents Project of Yunnan Province(2015HB013)the Scientific Research Foundation of the Education Department of Yunnan Province(2018JS452)。
文摘Exploring a new tuning way to facilely realize single-band red emission in trivalent rare-earth ions(RE3+) doped upconversion(UC) materials is still desirable.In this work,the intense single-band red emission is achieved by co-doping only Ho3+in the BiOCl:Er3+ under 1550 nm excitation.In the BiOCl layered host,co-doping Ho3+can further enhance the red emission and simultaneously suppress the green emission of Er3+,and thus obviously improve the red-to-green(R/G) ratio.It is found that Ho3+does not se rve as ene rgy trapping through the 5 I6 state as in traditional UC materials but acts as ET bridge(4 S3/2,2 H11/2(Er3+)→5 F4,5 S2(Ho3+)→4 F9/2(Er3+)).The tuning mechanism of Ho3+is discussed in detail and further confirms through a comparative experiment.Our research gives an unusual perspective to tune the UC behavior of Er3+through co-doping Ho3+,which might be inspiring for achievement of single-band red UC emission.
基金supported by the Shanghai Scientific Research Innovation Projects(14ZZ037)the Basic Research Project of Shanghai Science and Technology Commission(12JC1408500)the Fundamental Research Funds for the Central Universities(2011KJ018)
文摘Yb3＋ and Er3＋ ions co-doped NaYF4 nanocrystals were synthesized with different amounts of NaOH via oleic acid（OA）-assisted hydrothermal process. X-ray diffraction（XRD）, scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, Fourier transform infrared spectroscopy（FTIR）, and photoluminescence spectra were used to characterize the products. The result indicated that the introduction of Na OH into the initial reaction solution effectively promoted the cubic（α-） to hexagonal（β-） phase transition of NaYF4：Yb3＋,Er3＋ nanocrystals, while excessive amount of Na OH favored the formation of α-NaYF4：Yb3＋,Er3＋ nanocrystals. Besides, with the increase of Na OH amount, the morphologies of β-NaYF4：Yb3＋,Er3＋ nanocrystals varied from irregular nanobranch to uniform nanorod. Further investigation revealed that the addition of Na OH could facilitate the deprotonation of OA, leading to the formation of oleate（OA–）, and meanwhile increased the concentration of OH– ions, inducing consequently the phase transition and morphology evolution of NaYF4：Yb3＋,Er3＋ nanocrystals. Moreover, the upconversion luminescence properties of NaYF4：Yb3＋,Er3＋ nanocrystals were systematically investigated. It was found that the upconversion emissions not only depended on the phase and morphology but also were influenced by the surface groups.
