Sr_(2)NaMg_(2)V_(3)O_(12):xEu phosphors with uniform particle size/morphology and good dispersion can be synthesized via solid state reaction.Under the optimum excitation wavelength of ~340 nm,the Sr_(2)NaMg_(2)V_(3)O...Sr_(2)NaMg_(2)V_(3)O_(12):xEu phosphors with uniform particle size/morphology and good dispersion can be synthesized via solid state reaction.Under the optimum excitation wavelength of ~340 nm,the Sr_(2)NaMg_(2)V_(3)O_(12):xEu phosphor displays the broad emission band at ~500 nm(blue-green emission,^(3)T_(1,2)→^(1)A_(1) transition of[VO_(4)]^(3-))and sharp emission peak at~610 nm(red emission,^(5)D_(0)→^(7)F_(2) transition of Eu^(3+)),respectively.With the Eu^(3+)content increasing,the emission intensity of[VO_(4)]^(3-)decreases gradually while the emission intensity of Eu^(3+)increases,which is ascribed to the energy transfer from[VO_(4)]^(3-)to Eu^(3+)ions.The decay time of[VO_(4)]^(3-)(-500 nm)increases gradually with the Eu^(3+)content increasing.The energy transfer efficiency and mechanism of[VO_(4)]^(3-)→Eu^(3+)ions were analyzed,respectively.The emission color of Sr_(2)NaMg_(2)V_(3)O_(12):xEu phosphor was regulated from green to red via altering the Eu^(3+)ions concentration.It is delightful for us that the white color emission can be just achieved when the Eu^(3+)content is 5 at%(x=0.05),and the w-LED can be assembled.By studying the luminescence temperature dependence and activation energy of Sr_(2)NaMg_(2)V_3O_(12):xEu phosphor,it is shown that the phosphor has good thermal stability.The Sr_(2)NaMg_(2)V_3O_(12):xEu powder is expected to be a new type of phosphor widely used in light and display areas.展开更多
Y 1-a, Gd a) 3-x(Al 1-b, Ga b) 5O 12∶Ce 3+ x was synthesized by high-temperature solid state reaction in reducing atmosphere based on high purity raw materials. The influences of Y 3+, Gd 3+, Al 3...Y 1-a, Gd a) 3-x(Al 1-b, Ga b) 5O 12∶Ce 3+ x was synthesized by high-temperature solid state reaction in reducing atmosphere based on high purity raw materials. The influences of Y 3+, Gd 3+, Al 3+, Ga 3+ and activator-Ce 3+ on the performance of the phosphor were investigated. Ce 3+ is the luminescent center and activates the phosphor after it replaces Y partially. When x is less than 0.12, the volume of the crystal and the emission intensity of the phosphor increase with the quantity of Ce 3+. When CeO 2 is added too much, the phase CeAlO 3 will appear. The excitation and emission peaks of the phosphor will shift to longer wavelength when the amount of Gd 3+ increases. The wavelength of the emission peak can shift about 20 nm when a equals 0.45. In opposite, the excitation and emission peaks will shift to shorter wavelength, when part of Al 3+ is replaced by Ga 3+. The wavelength of the emission peak can shift about 20 nm when b equals 0.55. Through the replacemeat of Y 3+ or Al 3+ by Gd 3+ or Ga 3+, the emission peak of the phosphor can be adjusted from 520 to 560 nm. In this way, the phosphor is more suitable for different chips.展开更多
The work focuses on the utilization of the conventional solid-state sintering procedure to synthesize white phosphors Ca_(2)InTaO_(6):xDy^(3+)(0.02≤x≤0.12).Utilizing X-ray diffraction,the phase structure of samples ...The work focuses on the utilization of the conventional solid-state sintering procedure to synthesize white phosphors Ca_(2)InTaO_(6):xDy^(3+)(0.02≤x≤0.12).Utilizing X-ray diffraction,the phase structure of samples was examined,and the crystal structure was refined using the Rietveld method.A scanning electron microscope was used to analyze the microstructure of sample.First-principles calculations confirm that the indirect bandgap of Ca_(2)InTaO_(6)is 3.786 eV,The luminous properties and energy transfer mechanism of Ca_(2)InTaO_(6):xDy^(3+)were studied using photoluminescence spectroscopy.The~4F_(9/2)→~6H_(13/2)transition of Dy^(3+)ions is responsible for the greatest emission peak,which was measured at 575 nm.According to research,the lifespan falls as the concentration of Dy^(3+)doping amount rises because of frequent interaction and ene rgy transfer between Dy^(3+)ions.The correlated color temperature of the WLEDs packaged with Ca_(2)InTaO_(6):0.08Dy^(3+)is 4677 K and CIE 1931 chromaticity coordinates are(0.3578,0.3831).Meantime,the phosphor also shows outstanding te mperature stability property,which maintains 83.8%of its initial emission intensity at 450 K(activation energy of 0.1467 eV).The W-LEDs retain their performance for 100 min when powered at 3.4 V voltage and 600 mA current,demonstrating the packed W-LEDs'sustaine d operation at high temperatures.展开更多
Novel Sr3Gd（1-x）DyxNa（PO4）3F （SGNP：xDy3＋, x=0.01, 0.03, 0.05, 0.07, 0.09, 0.11） phosphors were synthesized by a conventional solid-state reaction method at different compositions. The X-ray diffraction results...Novel Sr3Gd（1-x）DyxNa（PO4）3F （SGNP：xDy3＋, x=0.01, 0.03, 0.05, 0.07, 0.09, 0.11） phosphors were synthesized by a conventional solid-state reaction method at different compositions. The X-ray diffraction results confirmed that the as-prepared samples were pure phase. The phosphor had two intense emission bands centering at 481 and 574 nm which could be attributed to the 4F9/2→6H15/2 transition and the 4F9/2→6H13/2 transition, respectively. The chromaticity coordinates （x, y） of this phosphor were calculated to be （0.3054, 0.3354） located on the region of white light region when excited at 350 nm. The concentration quenching mechanism of Dy3＋ was ascribed to the dipole-dipole interaction. The current research suggested that the phosphors might be potential application in the w-LEDs.展开更多
A broadband blue-emitting Sr_(1-x)Ca_(x)Lu_(2)O_(4):Ce^(3+)(x=0-0.2) phospho rs were synthesized,which can be used for near-UV pumped white light-emitting diodes(w-LEDs).The crystal structures,photoluminescence pro pe...A broadband blue-emitting Sr_(1-x)Ca_(x)Lu_(2)O_(4):Ce^(3+)(x=0-0.2) phospho rs were synthesized,which can be used for near-UV pumped white light-emitting diodes(w-LEDs).The crystal structures,photoluminescence pro perties,external quantum efficiency,the rmal stability and application perfo rmance of Sr_(1-x)Ca_(x)Lu_(2)O_(4):Ce^(3+),by partially substituting Sr^(2+) with Ca^(2+)(x=0-0.2),were studied by various analytical techniques.When the Ca/Sr ratio of Sr_(1-x)Ca_(x)Lu_(2)O_(4):Ce^(3+) gradually increases,the emission peak of Sr_(1-x)Ca_(x)Lu_(2)O_(4):Ce^(3+) red-shiftes from 459 to 465 nm,corrected external quantum efficiency increases from 31.8% to 42.9%,and the thermal stability is also improved.The mechanism of the changes of the photoluminescence emission and excitation spectra,external quantum efficiency and thermal stability properties was also investigated in detail.In addition,a w-LED was fabricated by using SrLu_(2)O_(4):Ce^(3+)(blue),β-sialon:Eu^(2+)(green) and(Sr,Ca)AlSiN_(3):Eu^(2+)(red) phosphors combined with a 405 nm near-UV LED chip,and its color rendering index(CRI) reaches 96.0.When Sr_(0.8)Ca_(0.2)Lu_(2)O_(4):Ce^(3+) is applied as blue phosphor to substitute SrLu_(2)O_(4):Ce^(3+),the obtained w-LED devices have high luminous efficiency,and CRI greater than 95.0.These re sults show that the Sr_(1-x)Ca_(x)Lu_(2)O_(4):Ce^(3+) can be potential blue phosphors for n-UV pumped high CRI w-LEDs application.展开更多
基金Project supported by the National Natural Science Foundation of China (51402125)China Postdoctoral Science Foundation (2017M612175,2022M711438)+2 种基金Special Fund of Postdoctoral Innovation Project in Shandong Province (201603061)"New Universities 20"Foundation of Jinan (2021GXRC099)Natural Science Foundation of Shandong Province (ZR2020ME045,ZR2020ME046)。
文摘Sr_(2)NaMg_(2)V_(3)O_(12):xEu phosphors with uniform particle size/morphology and good dispersion can be synthesized via solid state reaction.Under the optimum excitation wavelength of ~340 nm,the Sr_(2)NaMg_(2)V_(3)O_(12):xEu phosphor displays the broad emission band at ~500 nm(blue-green emission,^(3)T_(1,2)→^(1)A_(1) transition of[VO_(4)]^(3-))and sharp emission peak at~610 nm(red emission,^(5)D_(0)→^(7)F_(2) transition of Eu^(3+)),respectively.With the Eu^(3+)content increasing,the emission intensity of[VO_(4)]^(3-)decreases gradually while the emission intensity of Eu^(3+)increases,which is ascribed to the energy transfer from[VO_(4)]^(3-)to Eu^(3+)ions.The decay time of[VO_(4)]^(3-)(-500 nm)increases gradually with the Eu^(3+)content increasing.The energy transfer efficiency and mechanism of[VO_(4)]^(3-)→Eu^(3+)ions were analyzed,respectively.The emission color of Sr_(2)NaMg_(2)V_(3)O_(12):xEu phosphor was regulated from green to red via altering the Eu^(3+)ions concentration.It is delightful for us that the white color emission can be just achieved when the Eu^(3+)content is 5 at%(x=0.05),and the w-LED can be assembled.By studying the luminescence temperature dependence and activation energy of Sr_(2)NaMg_(2)V_3O_(12):xEu phosphor,it is shown that the phosphor has good thermal stability.The Sr_(2)NaMg_(2)V_3O_(12):xEu powder is expected to be a new type of phosphor widely used in light and display areas.
文摘Y 1-a, Gd a) 3-x(Al 1-b, Ga b) 5O 12∶Ce 3+ x was synthesized by high-temperature solid state reaction in reducing atmosphere based on high purity raw materials. The influences of Y 3+, Gd 3+, Al 3+, Ga 3+ and activator-Ce 3+ on the performance of the phosphor were investigated. Ce 3+ is the luminescent center and activates the phosphor after it replaces Y partially. When x is less than 0.12, the volume of the crystal and the emission intensity of the phosphor increase with the quantity of Ce 3+. When CeO 2 is added too much, the phase CeAlO 3 will appear. The excitation and emission peaks of the phosphor will shift to longer wavelength when the amount of Gd 3+ increases. The wavelength of the emission peak can shift about 20 nm when a equals 0.45. In opposite, the excitation and emission peaks will shift to shorter wavelength, when part of Al 3+ is replaced by Ga 3+. The wavelength of the emission peak can shift about 20 nm when b equals 0.55. Through the replacemeat of Y 3+ or Al 3+ by Gd 3+ or Ga 3+, the emission peak of the phosphor can be adjusted from 520 to 560 nm. In this way, the phosphor is more suitable for different chips.
基金Project supported by the Science and Technology Foundation of Guizhou Province(20201Y271)。
文摘The work focuses on the utilization of the conventional solid-state sintering procedure to synthesize white phosphors Ca_(2)InTaO_(6):xDy^(3+)(0.02≤x≤0.12).Utilizing X-ray diffraction,the phase structure of samples was examined,and the crystal structure was refined using the Rietveld method.A scanning electron microscope was used to analyze the microstructure of sample.First-principles calculations confirm that the indirect bandgap of Ca_(2)InTaO_(6)is 3.786 eV,The luminous properties and energy transfer mechanism of Ca_(2)InTaO_(6):xDy^(3+)were studied using photoluminescence spectroscopy.The~4F_(9/2)→~6H_(13/2)transition of Dy^(3+)ions is responsible for the greatest emission peak,which was measured at 575 nm.According to research,the lifespan falls as the concentration of Dy^(3+)doping amount rises because of frequent interaction and ene rgy transfer between Dy^(3+)ions.The correlated color temperature of the WLEDs packaged with Ca_(2)InTaO_(6):0.08Dy^(3+)is 4677 K and CIE 1931 chromaticity coordinates are(0.3578,0.3831).Meantime,the phosphor also shows outstanding te mperature stability property,which maintains 83.8%of its initial emission intensity at 450 K(activation energy of 0.1467 eV).The W-LEDs retain their performance for 100 min when powered at 3.4 V voltage and 600 mA current,demonstrating the packed W-LEDs'sustaine d operation at high temperatures.
基金supported by National Natural Science Foundation of China(20976002)the Beijing Natural Science Foundation(2122012)Key Projects for Science and Technology of Beijing Education Commission(KZ201310011013)
文摘Novel Sr3Gd（1-x）DyxNa（PO4）3F （SGNP：xDy3＋, x=0.01, 0.03, 0.05, 0.07, 0.09, 0.11） phosphors were synthesized by a conventional solid-state reaction method at different compositions. The X-ray diffraction results confirmed that the as-prepared samples were pure phase. The phosphor had two intense emission bands centering at 481 and 574 nm which could be attributed to the 4F9/2→6H15/2 transition and the 4F9/2→6H13/2 transition, respectively. The chromaticity coordinates （x, y） of this phosphor were calculated to be （0.3054, 0.3354） located on the region of white light region when excited at 350 nm. The concentration quenching mechanism of Dy3＋ was ascribed to the dipole-dipole interaction. The current research suggested that the phosphors might be potential application in the w-LEDs.
基金Project supported by the National Key Research and Development Program of China(2017YFB0404301)。
文摘A broadband blue-emitting Sr_(1-x)Ca_(x)Lu_(2)O_(4):Ce^(3+)(x=0-0.2) phospho rs were synthesized,which can be used for near-UV pumped white light-emitting diodes(w-LEDs).The crystal structures,photoluminescence pro perties,external quantum efficiency,the rmal stability and application perfo rmance of Sr_(1-x)Ca_(x)Lu_(2)O_(4):Ce^(3+),by partially substituting Sr^(2+) with Ca^(2+)(x=0-0.2),were studied by various analytical techniques.When the Ca/Sr ratio of Sr_(1-x)Ca_(x)Lu_(2)O_(4):Ce^(3+) gradually increases,the emission peak of Sr_(1-x)Ca_(x)Lu_(2)O_(4):Ce^(3+) red-shiftes from 459 to 465 nm,corrected external quantum efficiency increases from 31.8% to 42.9%,and the thermal stability is also improved.The mechanism of the changes of the photoluminescence emission and excitation spectra,external quantum efficiency and thermal stability properties was also investigated in detail.In addition,a w-LED was fabricated by using SrLu_(2)O_(4):Ce^(3+)(blue),β-sialon:Eu^(2+)(green) and(Sr,Ca)AlSiN_(3):Eu^(2+)(red) phosphors combined with a 405 nm near-UV LED chip,and its color rendering index(CRI) reaches 96.0.When Sr_(0.8)Ca_(0.2)Lu_(2)O_(4):Ce^(3+) is applied as blue phosphor to substitute SrLu_(2)O_(4):Ce^(3+),the obtained w-LED devices have high luminous efficiency,and CRI greater than 95.0.These re sults show that the Sr_(1-x)Ca_(x)Lu_(2)O_(4):Ce^(3+) can be potential blue phosphors for n-UV pumped high CRI w-LEDs application.
