Effective colour modulation of upconversion emissions in lanthanide-doped nanomaterials becomes even more important for fundamental and applied research.Herein,on the one hand,by raising the content of doped Yb^(3+)fr...Effective colour modulation of upconversion emissions in lanthanide-doped nanomaterials becomes even more important for fundamental and applied research.Herein,on the one hand,by raising the content of doped Yb^(3+)from 10 mol%to 50 mol%,a significant increase of the red/green emission ratio from 4.0 to 68.2 is observed in K_(2)NaScF_(6):Yb/Er nanocrystals.This yellow to red colour change is attributed to the increased cross relaxation between Er^(3+)and Yb^(3+)caused by the increased Yb^(3+)amount,^(4) S_(3/2)(Er^(3+))^(+2) F7/2(Yb^(3+))→4 I13/2(Er^(3+))^(+2) F5/2(Yb^(3+)).On the other hand,the upconversion green and red emission of K_(2)NaScF_(6):Yb/Er(20/2 mol%)nanocrystals are intensified 10.6 and 8.8 folds,respectively,after an active shell(K_(2)NaScF_(6):Yb)is epitaxially grown,which are more effective than the7.4-and 6.4-fold enhancement from an inert shell(K_(2)NaScF_(6))growth.Moreover,the shell thickness from2.85 to 9.5 nm through controlling the molar ratio of shell-precursor to core from 1:2 to 3:1 can be easily realized.This study will provide more opportunities for the application of K_(2)NaScF_(6):Yb/Ln nanoparticles in varied fields such as theranostics,photovoltaics,and photocatalysis.展开更多
Smart windows are an important strategy to reduce the energy consumption in buildings,which accounts for as much as 30%e40%of the society's energy consumption.VO_(2)-based thermochromic materials can intelligently...Smart windows are an important strategy to reduce the energy consumption in buildings,which accounts for as much as 30%e40%of the society's energy consumption.VO_(2)-based thermochromic materials can intelligently regulate the solar heat gains of building interiors.However,the unmatched thermal emissivity(ε)modulation of traditional VO_(2)/glass systems,i.e.,high emissivity at low temperatures and low emissivity at high temperatures,leads to additional heating and cooling energy loads in winter and summer,respectively.In this study,we propose a novel VO_(2)/polyacrylonitrile(PAN)/AgNW multilayer possessing flexible Ag nanowire supported FabryePerot cavities,which synchronously achieves high modulation abilities in both solar spectrum(DT_(sol) of 13.6%)and middle infrared region(D 3 of 0.50 at 8-13 mm).These achievements are the best among reports for pure VO_(2) smart windows.This study provides a flexible and effective protocol to dynamically enhance the light and heat utilization for practical building windows.展开更多
Employing a simple and efficient method of electro-chemical anodization, ZnO nanowire films are fabricated on Zn foil, and an ultraviolet （UV） sensor prototype is formed for investigating the electronic transport th...Employing a simple and efficient method of electro-chemical anodization, ZnO nanowire films are fabricated on Zn foil, and an ultraviolet （UV） sensor prototype is formed for investigating the electronic transport through back-to-back double junctions. The UV （365 nm） responses of surface-contacted ZnO film are provided by I-V measurement, along with the current evolution process by on/off of UV illumination. In this paper, the back-to-back metal-seconductor-metal （M-S-M） model is used to explain the electronic transport of a ZnO nanowire film based structure. A thermionic-field electron emission mechanism is employed to fit and explain the as-observed UV sensitive electronic transport properties of ZnO film with surface-modulation by oxygen and water molecular coverage.展开更多
The bonded distributed feedback（DFB） fiber laser（FL） acoustic emission sensor and the intensity response of the DFB-FL to external acoustic emissions are investigated. The dynamic sensitivity of the DFB-FL is cali...The bonded distributed feedback（DFB） fiber laser（FL） acoustic emission sensor and the intensity response of the DFB-FL to external acoustic emissions are investigated. The dynamic sensitivity of the DFB-FL is calibrated by a referenced piezoelectric receiver. In the DFB-FL we used here, the minimum detectable signal is2 × 10^（-6）m∕s at 5 kHz. Using wavelet packet technology, the collected signals are analyzed, which confirms that an intensity-modulated DFB-FL sensor can be used to detect acoustic emission signals.展开更多
基金Project supported by the National Natural Science Foundation of China(21871137,21671101)the Research Fund for the Doctoral Program of Liaocheng University(318051832)the Innovation Team of Higher Educational Science and Technology Program of Shandong Province(2019KIA025)。
文摘Effective colour modulation of upconversion emissions in lanthanide-doped nanomaterials becomes even more important for fundamental and applied research.Herein,on the one hand,by raising the content of doped Yb^(3+)from 10 mol%to 50 mol%,a significant increase of the red/green emission ratio from 4.0 to 68.2 is observed in K_(2)NaScF_(6):Yb/Er nanocrystals.This yellow to red colour change is attributed to the increased cross relaxation between Er^(3+)and Yb^(3+)caused by the increased Yb^(3+)amount,^(4) S_(3/2)(Er^(3+))^(+2) F7/2(Yb^(3+))→4 I13/2(Er^(3+))^(+2) F5/2(Yb^(3+)).On the other hand,the upconversion green and red emission of K_(2)NaScF_(6):Yb/Er(20/2 mol%)nanocrystals are intensified 10.6 and 8.8 folds,respectively,after an active shell(K_(2)NaScF_(6):Yb)is epitaxially grown,which are more effective than the7.4-and 6.4-fold enhancement from an inert shell(K_(2)NaScF_(6))growth.Moreover,the shell thickness from2.85 to 9.5 nm through controlling the molar ratio of shell-precursor to core from 1:2 to 3:1 can be easily realized.This study will provide more opportunities for the application of K_(2)NaScF_(6):Yb/Ln nanoparticles in varied fields such as theranostics,photovoltaics,and photocatalysis.
基金supported in part by funding from the National Natural Science Foundation of China(NSFC,Contract Nos.:51502268,51325203)the Open Project of State Key Laboratory of Advanced Special Steel,Shanghai Key Laboratory of Advanced Ferrometallurgy,Shanghai University(SKLASS 2022e04)+1 种基金the Science and Technology Commission of Shanghai Municipality(No.19DZ2270200)the Provincial and Ministerial Co-construction of Collaborative Innovation Center for Resource Materials(Contract No.:zycl202008).
文摘Smart windows are an important strategy to reduce the energy consumption in buildings,which accounts for as much as 30%e40%of the society's energy consumption.VO_(2)-based thermochromic materials can intelligently regulate the solar heat gains of building interiors.However,the unmatched thermal emissivity(ε)modulation of traditional VO_(2)/glass systems,i.e.,high emissivity at low temperatures and low emissivity at high temperatures,leads to additional heating and cooling energy loads in winter and summer,respectively.In this study,we propose a novel VO_(2)/polyacrylonitrile(PAN)/AgNW multilayer possessing flexible Ag nanowire supported FabryePerot cavities,which synchronously achieves high modulation abilities in both solar spectrum(DT_(sol) of 13.6%)and middle infrared region(D 3 of 0.50 at 8-13 mm).These achievements are the best among reports for pure VO_(2) smart windows.This study provides a flexible and effective protocol to dynamically enhance the light and heat utilization for practical building windows.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11274082 and 51172194)the Excellent Young Scientist Research Award Fund of Shandong Province,China(Grant No.BS2011CL002)
文摘Employing a simple and efficient method of electro-chemical anodization, ZnO nanowire films are fabricated on Zn foil, and an ultraviolet （UV） sensor prototype is formed for investigating the electronic transport through back-to-back double junctions. The UV （365 nm） responses of surface-contacted ZnO film are provided by I-V measurement, along with the current evolution process by on/off of UV illumination. In this paper, the back-to-back metal-seconductor-metal （M-S-M） model is used to explain the electronic transport of a ZnO nanowire film based structure. A thermionic-field electron emission mechanism is employed to fit and explain the as-observed UV sensitive electronic transport properties of ZnO film with surface-modulation by oxygen and water molecular coverage.
基金supported by the National 863 Program of China(No.2014AA093406)the Youth Innovation Promotion Association of CAS(No.2016106)+1 种基金the Project of Observation Instrument Development for Integrated Geophysical Field of China Mainland(No.Y201606)the Key Project of Hebei Educational Committee(No.BJ2016048)
文摘The bonded distributed feedback（DFB） fiber laser（FL） acoustic emission sensor and the intensity response of the DFB-FL to external acoustic emissions are investigated. The dynamic sensitivity of the DFB-FL is calibrated by a referenced piezoelectric receiver. In the DFB-FL we used here, the minimum detectable signal is2 × 10^（-6）m∕s at 5 kHz. Using wavelet packet technology, the collected signals are analyzed, which confirms that an intensity-modulated DFB-FL sensor can be used to detect acoustic emission signals.
