Bifunctional applications in solid state lighting and optical thermometry are attractive in the optical field.Despite Eu^(3+)doped phosphors are widely used in white-LEDs,phosphors with high temperature sensitivity re...Bifunctional applications in solid state lighting and optical thermometry are attractive in the optical field.Despite Eu^(3+)doped phosphors are widely used in white-LEDs,phosphors with high temperature sensitivity remain rare.Herein,NaLnTe_(2)O_(7):Eu^(3+)(Ln=Y and Gd)phosphors were synthesized using a rapid microwave-assisted solidstate(MASS)method to fulfill these applications.Under 395 nm excitation,NaLnTe_(2)O_(7):Eu^(3+)exhibit the characteristic ^(5)D_(0)→^(7)F_(J)(J=1–4)transitions of Eu^(3+).Substituting Gd^(3+) for Y^(3+) enhances the luminescence by approximately 2.42 times.Structural analyses reveal that the improved luminescent properties are attributed to the more distorted and appropriate coordination environment in NaGdTe_(2)O_(7):Eu^(3+).Finally,white-LEDs using NaGdTe_(2)O_(7):Eu^(3+)as the red-component produce white light with high Ra of 89.Furthermore,the distinct thermal responses of the ^(5)D_(0)→^(7)F_(J) transitions enable NaLnTe_(2)O_(7):Eu^(3+)to function as temperature sensors via fluorescence intensity ratio(FIR)strategy.NaYTe_(2)O_(7):Eu^(3+)possesses the maximum relative/absolute sensitivity of 1.45%/15.93%K^(-1),whereas NaGdTe_(2)O_(7):Eu^(3+)achieves the maximum relative/absolute sensitivity of 1.53%/30.24% K^(-1).This work highlights the significance of cationic substitution in enhancing luminescent properties for multifunctional applications.展开更多
The red, green and blue （R/G/B） tricolor emitting phosphors Ba2ZnSi2O7 co-doped with Ce3＋and Eu3＋were synthesized in air atmosphere by a conventional high temperature solid-state reaction technique. All of the exc...The red, green and blue （R/G/B） tricolor emitting phosphors Ba2ZnSi2O7 co-doped with Ce3＋and Eu3＋were synthesized in air atmosphere by a conventional high temperature solid-state reaction technique. All of the excitation spectrum of the phosphor Ba2ZnSi2O7：Ce,Eu showed a strong broad band absorption in the n-UV region whenever monitored by red （630 nm）-emitting or by green （500 nm）-and blue （402 nm）-emitting. Under the excitation of 330 nm, the emission spectrum containing a blue-violet emis-sion band, a green emission and four sharp lines originated from the characteristic transitions of Ce3＋, Eu2＋and Eu3＋ions, of which the relative intensities of the three emission bands could be controlled by the doping concentration of Ce3＋. The ca. CIE chromaticity co-ordinates （x=0.317, y=0.309） of the phosphor Ba1.94ZnSi2O7：0.03Eu,0.01Ce was very close to the standard white （x=0.33, y=0.33）, which suggested that it was a novel single-phased white-light emitting phosphor for LED-based near-UV chip. The mechanisms of energy transfer from Eu2＋to Eu3＋via Ce3＋was also discussed.展开更多
Red phosphors, Li2Sr0.996 Si O4： Pr3＋0.004, with different hydrothermal conditions were prepared via hydrothermal synthesis and then heat-treatment. The chemical structures of the phosphors were identified with X-ra...Red phosphors, Li2Sr0.996 Si O4： Pr3＋0.004, with different hydrothermal conditions were prepared via hydrothermal synthesis and then heat-treatment. The chemical structures of the phosphors were identified with X-ray diffraction（XRD）. Surface morphological features were observed by scanning electron microscopic（SEM） investigation. Spectra of excitation and emission for the phosphors were also obtained by a spectrophotometer. Results showed that the optimum conditions were as follows： p H value of solution was 1–2, reaction temperature was at 180 oC for 24 h. The as-prepared phosphors exhibited two excitation dominant peaks at 451 and 486 nm, attributed to transitions of 3H4→3P2 and 3H4→3P0 of Pr3＋, respectively. A narrow emission peak at 610 nm corresponded to the energy level transition of 3P0→3H6 of Pr3＋ under excitation of light at 451 nm, which indicated promising candidate red phosphors for blue LED chips.展开更多
Spherical YAG：Ce^3＋ phosphor particles with narrow size distribution were prepared by spray pyrolysis. The effects of the concentration of solution, the flow rate of cartier gas and the annexing temperature on the p...Spherical YAG：Ce^3＋ phosphor particles with narrow size distribution were prepared by spray pyrolysis. The effects of the concentration of solution, the flow rate of cartier gas and the annexing temperature on the phosphor morphology were studied. The productivity of precursor particles shows a trend of drop after rising with the increase of concentration Raising the flow rate of nitrogen can improve the productivity of the precursor particles. Phosphor prepared by spray pyrolysis has obviously higher emission intensity than that synthesized by solid state reaction, spray pyrolysis makes Ce^3＋ ions well distributed in the crystal lattice as the luminescent centers, and phosphor particles have regular sphericity and narrow size distribution.展开更多
Developing high efficient and stable red-emitting phosphors is very important in the areas of white lightingemitting diode(white-LED)and plant growth.Herein,series of Eu^(3+)-activated MF_(2)(M^(2+)=Ca^(2+),Sr^(2+),Ba...Developing high efficient and stable red-emitting phosphors is very important in the areas of white lightingemitting diode(white-LED)and plant growth.Herein,series of Eu^(3+)-activated MF_(2)(M^(2+)=Ca^(2+),Sr^(2+),Ba^(2+))red-emitting nanoparticles(NPs)were synthesized at room temperature.Excited at 394 nm,these resulting NPs can emit dazzling red emissions and their fluorescence intensities are sensitive to both dopant content and host compound.Moreover,it is found that the studied samples have admirable thermal stability,high quantum efficiencies and color purities,which can be regulated via changing host material.To assess the possible application of final products,three different white-LEDs were packaged by using Eu^(3+)-activated MF_(2)(M^(2+)=Ca^(2+),Sr^(2+),Ba^(2+))red-emitting NPs.Clearly,these manufactured white-LEDs can produce glaring warm white with satisfied electroluminescence behaviors,i.e.low correlated color temperature(<5000 K)and high color rendering index(>80).Furthermore,via using the designed NPs,three red-emitting LEDs were also fabricated so as to identify their applications in plant growth.Our findings imply that Eu^(3+)-activated MF_(2)(M^(2+)=Ca^(2+),Sr^(2+),Ba^(2+))NPs are well-suited for dual-functional lighting as red-emitting converters in the realms of white-LED and artificial plant growth LED.展开更多
基金financially supported by the Caiyun Postdoctoral Innovation Project(No.C615300504089)Yunnan Fundamental Research Project(No.202401AS070128)National Natural Science Foundation of China(No.22165031).
文摘Bifunctional applications in solid state lighting and optical thermometry are attractive in the optical field.Despite Eu^(3+)doped phosphors are widely used in white-LEDs,phosphors with high temperature sensitivity remain rare.Herein,NaLnTe_(2)O_(7):Eu^(3+)(Ln=Y and Gd)phosphors were synthesized using a rapid microwave-assisted solidstate(MASS)method to fulfill these applications.Under 395 nm excitation,NaLnTe_(2)O_(7):Eu^(3+)exhibit the characteristic ^(5)D_(0)→^(7)F_(J)(J=1–4)transitions of Eu^(3+).Substituting Gd^(3+) for Y^(3+) enhances the luminescence by approximately 2.42 times.Structural analyses reveal that the improved luminescent properties are attributed to the more distorted and appropriate coordination environment in NaGdTe_(2)O_(7):Eu^(3+).Finally,white-LEDs using NaGdTe_(2)O_(7):Eu^(3+)as the red-component produce white light with high Ra of 89.Furthermore,the distinct thermal responses of the ^(5)D_(0)→^(7)F_(J) transitions enable NaLnTe_(2)O_(7):Eu^(3+)to function as temperature sensors via fluorescence intensity ratio(FIR)strategy.NaYTe_(2)O_(7):Eu^(3+)possesses the maximum relative/absolute sensitivity of 1.45%/15.93%K^(-1),whereas NaGdTe_(2)O_(7):Eu^(3+)achieves the maximum relative/absolute sensitivity of 1.53%/30.24% K^(-1).This work highlights the significance of cationic substitution in enhancing luminescent properties for multifunctional applications.
基金Project supported by the National Natural Science Foundation of China(20971042)Specialized Research Fund for the Doctoral Program of Higher Education(20124306120005,20134306120009)+2 种基金Hunan Provincial Natural Science Foundation of China(2015JJ2100)Scientific Research Fund of Hunan Provincial Education Department(13C012)Aid Program for Science and Technology Innovative Research Team in Higher Educational Institutions of Hunan Province
文摘The red, green and blue （R/G/B） tricolor emitting phosphors Ba2ZnSi2O7 co-doped with Ce3＋and Eu3＋were synthesized in air atmosphere by a conventional high temperature solid-state reaction technique. All of the excitation spectrum of the phosphor Ba2ZnSi2O7：Ce,Eu showed a strong broad band absorption in the n-UV region whenever monitored by red （630 nm）-emitting or by green （500 nm）-and blue （402 nm）-emitting. Under the excitation of 330 nm, the emission spectrum containing a blue-violet emis-sion band, a green emission and four sharp lines originated from the characteristic transitions of Ce3＋, Eu2＋and Eu3＋ions, of which the relative intensities of the three emission bands could be controlled by the doping concentration of Ce3＋. The ca. CIE chromaticity co-ordinates （x=0.317, y=0.309） of the phosphor Ba1.94ZnSi2O7：0.03Eu,0.01Ce was very close to the standard white （x=0.33, y=0.33）, which suggested that it was a novel single-phased white-light emitting phosphor for LED-based near-UV chip. The mechanisms of energy transfer from Eu2＋to Eu3＋via Ce3＋was also discussed.
基金Project supported by the Fujian Provincial Key Project(2013H6020)
文摘Red phosphors, Li2Sr0.996 Si O4： Pr3＋0.004, with different hydrothermal conditions were prepared via hydrothermal synthesis and then heat-treatment. The chemical structures of the phosphors were identified with X-ray diffraction（XRD）. Surface morphological features were observed by scanning electron microscopic（SEM） investigation. Spectra of excitation and emission for the phosphors were also obtained by a spectrophotometer. Results showed that the optimum conditions were as follows： p H value of solution was 1–2, reaction temperature was at 180 oC for 24 h. The as-prepared phosphors exhibited two excitation dominant peaks at 451 and 486 nm, attributed to transitions of 3H4→3P2 and 3H4→3P0 of Pr3＋, respectively. A narrow emission peak at 610 nm corresponded to the energy level transition of 3P0→3H6 of Pr3＋ under excitation of light at 451 nm, which indicated promising candidate red phosphors for blue LED chips.
基金Project supported by National "The Tenth Five-Year"plan (2003BA316A01-03-05) and "The Tenth Five-Year"Plan(BE2004021) of Jiangsu provicce
文摘Spherical YAG：Ce^3＋ phosphor particles with narrow size distribution were prepared by spray pyrolysis. The effects of the concentration of solution, the flow rate of cartier gas and the annexing temperature on the phosphor morphology were studied. The productivity of precursor particles shows a trend of drop after rising with the increase of concentration Raising the flow rate of nitrogen can improve the productivity of the precursor particles. Phosphor prepared by spray pyrolysis has obviously higher emission intensity than that synthesized by solid state reaction, spray pyrolysis makes Ce^3＋ ions well distributed in the crystal lattice as the luminescent centers, and phosphor particles have regular sphericity and narrow size distribution.
基金supported by Public Welfare Science and Technology Plan Project of Ningbo(No.2023S074)National Natural Science Foundation of China(No.12374087)One health Interdisciplinary Research Project in Ningbo University(No.HY202405).
文摘Developing high efficient and stable red-emitting phosphors is very important in the areas of white lightingemitting diode(white-LED)and plant growth.Herein,series of Eu^(3+)-activated MF_(2)(M^(2+)=Ca^(2+),Sr^(2+),Ba^(2+))red-emitting nanoparticles(NPs)were synthesized at room temperature.Excited at 394 nm,these resulting NPs can emit dazzling red emissions and their fluorescence intensities are sensitive to both dopant content and host compound.Moreover,it is found that the studied samples have admirable thermal stability,high quantum efficiencies and color purities,which can be regulated via changing host material.To assess the possible application of final products,three different white-LEDs were packaged by using Eu^(3+)-activated MF_(2)(M^(2+)=Ca^(2+),Sr^(2+),Ba^(2+))red-emitting NPs.Clearly,these manufactured white-LEDs can produce glaring warm white with satisfied electroluminescence behaviors,i.e.low correlated color temperature(<5000 K)and high color rendering index(>80).Furthermore,via using the designed NPs,three red-emitting LEDs were also fabricated so as to identify their applications in plant growth.Our findings imply that Eu^(3+)-activated MF_(2)(M^(2+)=Ca^(2+),Sr^(2+),Ba^(2+))NPs are well-suited for dual-functional lighting as red-emitting converters in the realms of white-LED and artificial plant growth LED.
