In this paper,the fracture surfaces of a light-conversion film were observed using a scanning electron microscope(SEM),and then,the fluorescence spectra and mechanical properties of the film were tested.The SEM result...In this paper,the fracture surfaces of a light-conversion film were observed using a scanning electron microscope(SEM),and then,the fluorescence spectra and mechanical properties of the film were tested.The SEM results show that the average diameter of the light conversion agent is 500 nm.The results of the mechanical properties tests show that the tensile strengths of light-conversion film increase from9.86 to 12.16 MPa and that the strain at breakage increases from 2.37%to 2.75%.In addition,the application effects of the light-co nversion film were studied.The results indicate that plant height,length of the maximum leaf,width of the maximum leaf and breadth of the plants increase by 24.43%,15.30%,15.60%and 19.07%,respectively.The quality of Chinese flowering cabbages treated with the lightconversion film is superior,including a 9.09%increase in the soluble protein content,a 21.27%increase in the polyphenol content,and a 19.15%increase in the soluble sugar content.Based on these results,light-conversion films can be applied in agricultural production.展开更多
A series of Tb^3+ mono-doped and Ce^3+-Tb^3+ co-doped Sr3Gd2(Si3O9)2 phosphors with high thermal stability and quantum yields were successfully prepared via the solid state reaction. The as-prepared Sr3Gd2(Si3O9)2:Tb^...A series of Tb^3+ mono-doped and Ce^3+-Tb^3+ co-doped Sr3Gd2(Si3O9)2 phosphors with high thermal stability and quantum yields were successfully prepared via the solid state reaction. The as-prepared Sr3Gd2(Si3O9)2:Tb^3+ samples showed broad excitation spectrum from 250 to 400 nm and presented characteristic emission transitions ^5D4→^7FJ(J=6, 5, 4, 3) of Tb^3+ under 313 nm excitation, which were located at about 488, 541, 584 and 620 nm. The emission intensities of Tb^3+ rose steadily in Sr3Gd2(Si3O9)2 host with the increase of Tb^3+ concentration even though Gd^3+ ions were completely replaced by Tb^3+ ions. The Ce^3+ ion as a sensitizer could efficiently improve the performance of Tb^3+ ion. First, with Ce^3+ co-doping, the excitation spectrum of Tb^3+ monitored at 541 nm showed a similar band that responds to the violet emission of Ce^3+ monitored at 416 nm. Second, the quantum yields of Sr3Gd2(Si3O9)2:Tb^3+ phosphors could be enhanced from 26.6% to 80.2% by co-doping Ce^3+. Finally, the co-doping of Ce^3+ was also effective to improve the thermal stability of Sr3Gd2(Si3O9)2:Tb^3+. As the temperature rose to 150 oC, the emission intensity of Tb^3+ remained at about 83.6% of that measured at room temperature, which was better than the commercial YAG:Ce phosphor in terms of their thermal quenching properties. These results indicated that the as-prepared Sr3Gd2(Si3O9)2:Tb^3+,Ce^3+ samples could be used as green emission phosphors for possible applications in near ultraviolet based WLEDs.展开更多
Remarkable progress was made in the development of white-light-emitting diodes （LEDs）. White LEDs provided a light element having a semiconductor InGaN light-emitting chip （blue or UV LEDs） and luminescent phospho...Remarkable progress was made in the development of white-light-emitting diodes （LEDs）. White LEDs provided a light element having a semiconductor InGaN light-emitting chip （blue or UV LEDs） and luminescent phosphors. Here we reported the sialon s-phase of （Sr,Eu）2A12Si10N14O4. Eu^2＋ activator ions that were substituted for the strontium site represented a new type of yeUow-green phosphor that could be excited by blue LEDs used for application in the fabrication of white LEDs.展开更多
This paper reported a novel synthetic route to Eu2＋ doped SrSiN2 deep red phosphors for white light-emitting diodes. A series of single-phased and high-efficiency SrSiN2：Eu2＋ red phosphors were synthesized based on...This paper reported a novel synthetic route to Eu2＋ doped SrSiN2 deep red phosphors for white light-emitting diodes. A series of single-phased and high-efficiency SrSiN2：Eu2＋ red phosphors were synthesized based on this method. Their structure, morphology, luminescence, quantum efficiency （QE） and thermal quenching properties were investigated and compared with those of SrSiN2： Eu2＋ prepared by the conventional route. It was found that the addition of a small amount of Si3N4 could promote the formation of SrSiN2 from Sr2SisN8 phase. A highly uniform rod-shaped morphology was obtained based on this method. The X-ray powder diffraction and the Rietveld refinement analysis identified the preferential crystalline orientation growth. Under the blue light excitation, Eu2＋ doped SrSiN2 phosphors showed excellent optical properties. Compared with those prepared by the conventional approaches, the external QE of SrSiN2：Eu2＋ phosphor was greatly improved, allowing it a promising phosphor for white LEDs.展开更多
基金Project supported by the National Natural Science Foundation of China(21671070)Key Realm R&D Program of Guangdong Province(2019B020214001,2019B020223001)+2 种基金China Agriculture Research System(CARS-26)Guangdong Provincial Special Fund for Modern Agriculture Industry Technology Innovation Teams(2019LM119)the National Undergraduate Innovation and Entrepreneurship Training Program granted for Gening Xie(201910564035)。
文摘In this paper,the fracture surfaces of a light-conversion film were observed using a scanning electron microscope(SEM),and then,the fluorescence spectra and mechanical properties of the film were tested.The SEM results show that the average diameter of the light conversion agent is 500 nm.The results of the mechanical properties tests show that the tensile strengths of light-conversion film increase from9.86 to 12.16 MPa and that the strain at breakage increases from 2.37%to 2.75%.In addition,the application effects of the light-co nversion film were studied.The results indicate that plant height,length of the maximum leaf,width of the maximum leaf and breadth of the plants increase by 24.43%,15.30%,15.60%and 19.07%,respectively.The quality of Chinese flowering cabbages treated with the lightconversion film is superior,including a 9.09%increase in the soluble protein content,a 21.27%increase in the polyphenol content,and a 19.15%increase in the soluble sugar content.Based on these results,light-conversion films can be applied in agricultural production.
基金Project supported by National Natural Science Foundation of China(21571162)the Guangdong Province Enterprise-University-Academy Collaborative Project(2012B091100474)
文摘A series of Tb^3+ mono-doped and Ce^3+-Tb^3+ co-doped Sr3Gd2(Si3O9)2 phosphors with high thermal stability and quantum yields were successfully prepared via the solid state reaction. The as-prepared Sr3Gd2(Si3O9)2:Tb^3+ samples showed broad excitation spectrum from 250 to 400 nm and presented characteristic emission transitions ^5D4→^7FJ(J=6, 5, 4, 3) of Tb^3+ under 313 nm excitation, which were located at about 488, 541, 584 and 620 nm. The emission intensities of Tb^3+ rose steadily in Sr3Gd2(Si3O9)2 host with the increase of Tb^3+ concentration even though Gd^3+ ions were completely replaced by Tb^3+ ions. The Ce^3+ ion as a sensitizer could efficiently improve the performance of Tb^3+ ion. First, with Ce^3+ co-doping, the excitation spectrum of Tb^3+ monitored at 541 nm showed a similar band that responds to the violet emission of Ce^3+ monitored at 416 nm. Second, the quantum yields of Sr3Gd2(Si3O9)2:Tb^3+ phosphors could be enhanced from 26.6% to 80.2% by co-doping Ce^3+. Finally, the co-doping of Ce^3+ was also effective to improve the thermal stability of Sr3Gd2(Si3O9)2:Tb^3+. As the temperature rose to 150 oC, the emission intensity of Tb^3+ remained at about 83.6% of that measured at room temperature, which was better than the commercial YAG:Ce phosphor in terms of their thermal quenching properties. These results indicated that the as-prepared Sr3Gd2(Si3O9)2:Tb^3+,Ce^3+ samples could be used as green emission phosphors for possible applications in near ultraviolet based WLEDs.
基金Project supported by the Economic Affair (95-EC-17-A-07-S1-043)the National Science Council (94-2113-M-002-030)
文摘Remarkable progress was made in the development of white-light-emitting diodes （LEDs）. White LEDs provided a light element having a semiconductor InGaN light-emitting chip （blue or UV LEDs） and luminescent phosphors. Here we reported the sialon s-phase of （Sr,Eu）2A12Si10N14O4. Eu^2＋ activator ions that were substituted for the strontium site represented a new type of yeUow-green phosphor that could be excited by blue LEDs used for application in the fabrication of white LEDs.
文摘采用高温固相反应法制备了Sr_(1-x)Ca_xSi_2O_2N_2∶Eu^(2+)系列荧光粉,研究Y^(3+)离子掺入对荧光粉发光性能的影响。对于Sr Si_2O_2N_2∶Eu^(2+),Y^(3+)离子掺入主要起到稳定Eu^(2+)价态的作用,避免Eu^(2+)氧化为Eu^(3+),从而提高Sr Si_2O_2N_2∶Eu^(2+)的发光性能。对于Ca Sr Si_2O_2N_2∶Eu^(2+),Y^(3+)离子掺入除了稳定Eu^(2+)价态作用外,还能有效减小Eu^(2+)取代Ca^(2+)后晶格膨胀引起的应力,提高Eu^(2+)在晶格中的溶解度。Sr_(1-x)Ca_xSi_2O_2N_2∶Eu^(2+)(x=0,0.15,0.3,0.6,0.75,0.95)系列荧光粉中随着Ca含量的增加,共掺Y^(3+)离子对样品发光强度的提高程度也随之增加(20%~80%)。
基金supported by the National Basic Research Program of China(9732014CB643801)+1 种基金the National Natural Science Foundation of China(5110202151302016)
文摘This paper reported a novel synthetic route to Eu2＋ doped SrSiN2 deep red phosphors for white light-emitting diodes. A series of single-phased and high-efficiency SrSiN2：Eu2＋ red phosphors were synthesized based on this method. Their structure, morphology, luminescence, quantum efficiency （QE） and thermal quenching properties were investigated and compared with those of SrSiN2： Eu2＋ prepared by the conventional route. It was found that the addition of a small amount of Si3N4 could promote the formation of SrSiN2 from Sr2SisN8 phase. A highly uniform rod-shaped morphology was obtained based on this method. The X-ray powder diffraction and the Rietveld refinement analysis identified the preferential crystalline orientation growth. Under the blue light excitation, Eu2＋ doped SrSiN2 phosphors showed excellent optical properties. Compared with those prepared by the conventional approaches, the external QE of SrSiN2：Eu2＋ phosphor was greatly improved, allowing it a promising phosphor for white LEDs.
