Eu3+ doped self-activated Ca8ZrMg(PO4)6(SiO4) phosphor with tunable luminescence properties (original) (raw)
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2018
A novel tunable red- to yellow- emitting phosphor,(Ca4-x-y-zBaySrz)(PO4)2O:xEu2+is reported that displays a broad emission from 500 to 800nm, and its emission can be adjusted from red to yellow by changing Ba2+ and Sr2+ doping concentration. X-ray powder diffraction analysis confirmed the phase formation. Excitation and emissionspectra, and concentration dependence of emission intensity of the phosphor were investigated. The results showed that with increasing Ba2+/Sr2+ concentration, the emission peak wavelength blue-shift from 594 to 567 nm, and the color can be tuned from red to yellow. When single- phase (Ca2.95Ba0.5Sr0.5)(PO4)2O:0.05Eu2+phosphor is pumped by a blue InGaN light-emitting diode we obtain white light with color rending index between 80.0 and 88.0 and color temperatures between 3500 and 5450 K, suggesting that this material is competitive as a color conversion material for solid state lighting.
Journal of the American Ceramic Society, 2018
A series of novel red-emitting Ca 8 ZnLa 1-x Eu x (PO 4) 7 phosphors were successfully synthesized using the high-temperature solid-state reaction method. The crystal structure, photoluminescence spectra, thermal stability and quantum efficiency of the phosphors were investigated as a function of Eu 3+ concentration. Detailed analysis of their structural properties revealed that all the phosphors could be assigned as whitlockite-type β-Ca 3 (PO 4) 2 structures. Both the PL emission spectra and decay curves suggest that emission intensity is largely dependent on Eu 3+ concentration, with no quenching as the Eu 3+ concentration approaches 100%. A dominant red emission band centered at 611nm indicates that Eu 3+ occupies a low symmetry sites within the Ca 8 ZnLa (PO 4) 7 host lattice, which was confirm by Judd-Ofelt theory. Ca 8 ZnLa 1-x Eu x (PO 4) 7 phosphors exhibited good color coordinates (0.6516, 0.3480), high color purity (∼96.3%) and high quantum efficiency (∼78%). Temperature-dependent emission spectra showed that the phosphors possessed good thermal stability. A white light-emitting diode (LED) device were fabricated by integrating a mixture of obtained phosphors, commercial green-emitting and blue-emitting phosphors into a near-ultraviolet LED chip. The fabricated white LED device emits glaring white light with high color rendering index (83.9) and proper correlated color temperature (5570 K). These results demonstrate that the Ca 8 ZnLa 1-x Eu x (PO 4) 7 phosphors are a promising candidate for solid state lighting.
Optical Materials Express, 2014
A novel green emitting phosphor of Eu 2+ doped Ca 7 (PO 4) 2 (SiO 4) 2 was synthesized and its photoluminescence properties were investigated for application in UV LEDs. XRD was used to identify sample phase. Diffuse reflection spectra and photoluminescence spectra were used to investigate its photoluminescence properties. Ca 7 (PO 4) 2 (SiO 4) 2 :Eu 2+ showed an absorption ranging from 240 to 440 nm in ultraviolet range and a broad green emission band peaked at 522 nm. The concentration quenching mechanism and the key parameters for the fabrication of WLEDs, such as the temperature dependent photoluminescence and CIE value had also been studied.
Eu3+/Dy3+ ions co-doped Ca2La8(GeO4)6O2 (CLGO) phosphors were prepared by a pechini-type sol–gel method. The structural and morphological studies of the CLGO phosphors were carried out by measuring X-ray diffraction patterns and scanning electron microscope images. The photoluminescence (PL) spectra of the CLGO:Eu3+ phosphor exhibited the intense red emission due to the electric-dipole transition while the CLGO:Dy3+ phosphor showed the blue (4F9/2?6H15/2) and yellow (4F9/2?6H13/2) emissions with almost equal intensities. The Eu3+/Dy3+ ions co-doped CLGO phosphor showed the improved white light by shifting towards the warm white region. The energy transfer from Dy3+ to Eu3+ ions was investigated by means of PL intensities. The lifetime measurements were also performed for single-doped and codoped samples. The calculated chromaticity coordinates indicated that these phosphors may be suitable for the fabrication of near-UV excitation-based white light-emitting diodes.
Eu^2+-activated silicon-oxynitride Ca_3Si_2O_4N_2: a green-emitting phosphor for white LEDs
Optics Express, 2011
The green-emitting phosphor Ca 3 Si 2 O 4 N 2 :Eu 2+ was synthesized using a solid-state reaction. The luminescence properties, diffuse reflection spectrum, and thermal quenching were firstly studied, and a white lightemitting diode (wLED) was fabricated using the Eu 2+ -activated Ca 3 Si 2 O 4 N 2 phosphor. Eu 2+ -doped Ca 3 Si 2 O 4 N 2 exhibited a broad green emission band centered between 510 and 550 nm depending on the concentration of Eu 2+ . The optimal doping concentration of Eu 2+ in Ca 3 Si 2 O 4 N 2 was 1 mol%. The energy transfer between Eu 2+ ions proceeds by an electric multipolar interaction mechanism, with a critical transfer distance of approximately 30.08 Å. A wLED with an color-rendering index R a of 88.25 at a correlated color temperature of 6029 K was obtained by combining a GaN-based n-UV LED (380 nm) with the blue-emitting BaMgAl 10 O 17 :Eu 2+ , green-emitting Ca 3 Si 2 O 4 N 2 :Eu 2+ , and red-emitting CaAlSiN 3 :Eu 2+ phosphors. The results present Ca 3 Si 2 O 4 N 2 :Eu 2+ as an attractive candidate for use as a conversion phosphor for wLED applications.
The luminescence efficiency of green phosphorCa7(PO4)2(SiO4)2:Eu2+ for white light-emitting diode
Indonesian Journal of Electrical Engineering and Computer Science, 2022
This study examines the green-emission phosphor composition of Eu2+ doped Ca7(PO4)2(SiO4)2 to serve the goal of efficiency enhancement for the white light emitting diode (LED). The process of preparation and photo luminescent investigation of proposed phosphor composition was monitored under near UV excitation wavelength of the LED die. The sample phase was determined using X-ray diffractometer (XRD). To exploreCa7(PO4)2(SiO4)2:Eu2+ capabilities, the diffuse reflectance and photo lumine- scence spectral figures were employed. The ultraviolet absorption of Ca7(PO4)2(SiO4)2:Eu2+ ranged from 240 to 440 nm, with a wide band of green emission peaking at 522 nm. Besides the concentration quenching mechanism, we also focus on essential characteristics for white-light- emitting diode (WLED) production like temperature-dependent lumen output and chromaticity coordinates.
A novel white emitting phosphor of Dy3+ doped Ca19Mg2(PO4)14 for light-emitting diodes
Journal of Luminescence, 2014
A series of Dy 3 þ doped Ca 19 Mg 2 (PO 4) 14 phosphors were firstly synthesized by the solid-state reaction method. The phase purity and characteristic luminescent properties are investigated in detail by X-ray diffraction refinement, photoluminescence spectra and decay times measurement. Under 365 nm excitation, Ca 19 Mg 2 (PO 4) 14 :Dy 3 þ phosphor can exhibit intense warm white emission with CIE chromaticity coordinates (0.400, 0.452) and low correlated color temperature (3994 K). The optimal doping contents of Dy 3 þ in Ca 19 Mg 2 (PO 4) 14 is determined to be 2%. The thermal quenching property of Ca 19 Mg 2 (PO 4) 14 :Dy 3 þ is also investigated and it remains 60% of the initial emission intensity even when the temperature increases to 230 1C. The results show that Ca 19 Mg 2 (PO 4) 14 :Dy 3 þ can be a promising single phased white emitting phosphor for UV white LEDs.
Journal of Materials Chemistry, 2012
A new color-tunable Eu 2+-doped sodium aluminium silicate, Na 2ÀxÀy Al 2Àx Si x O 4 :yEu 2+ (0 # x # 1), phosphor system was investigated as a novel candidate for phosphor-converted white light-emitting diode (LED) applications and successfully synthesized by wet chemical methods based on the hydrolysis of tetraethyl orthosilicate (TEOS). Different crystal structures and emission spectra were obtained by varying the ratio of Al to Si in the phosphor Na 2Àx Al 2Àx Si x O 4 with x value ranging from 0.25 to 0.55. The Na 2ÀxÀy Al 2Àx Si x O 4 :yEu 2+ phosphor system emitted a maximum intensity at 470-600 nm when using a 395 nm excitation wavelength, and the emission was strongly affected by the crystal structures determined by the x value. Substitution of Eu 2+ affected the center wavelength and emission intensity due to changes in the crystal-field effect, which was strongly dependent on the crystal structure. The LED device exhibited an excellent color-rendering index R a of 93 at a correlated color temperature of 4258 K with CIE color coordinates of (0.3629, 0.3427) under a 20 mA forward-bias current. Based on these results, we are currently evaluating the potential application of Na 2ÀxÀy Al 2Àx Si x O 4 :yEu 2+ as a white-emitting UV-convertible phosphor.
A potential red emitting K4Ca(PO4)2: Eu3+ phosphor for white light emitting diodes
Journal of Luminescence, 2012
Europium (III) ions doped red phosphors K 4 Ca(PO 4) 2 were prepared first time by high temperature solid state reaction method. The prepared phosphors structure was examined by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) analyses. The thermal properties of the synthesized phosphor were investigated by differential scanning calorimetry (DSC) analysis. Photoluminescence (PL) spectra of K 4 Ca(PO 4) 2 :Eu 3 þ phosphors have shown strong red emission at 618 nm (5 D 0-7 F 2) with near UV an excitation wavelength of l exc ¼ 394 nm (7 F 0-5 L 6). In addition, the decay curves and CIE color coordinate measurements are also carried out. Hence, emission and excitation characterization of synthesized phosphors shows that the phosphors may be a promising red component for the application in the white light emitting diodes (WLEDs).
Acs Applied Materials & Interfaces, 2010
A series of single-composition emission-tunable Ca 9 Y(PO 4 ) 7 :Eu 2+ ,Mn 2+ phosphors were synthesized by solid-state reaction. The energy transfer from Eu 2+ to Mn 2+ in Ca 9 Y(PO 4 ) 7 host matrix was studied and demonstrated to be a resonant type via a dipole-quadrupole mechanism with the critical distance of ∼ 11 Å. The wavelength-tunable white light can be realized by coupling the emission bands centered at 486 and 638 nm ascribed to the contribution from Eu 2+ and Mn 2+ , respectively. By properly tuning the relative composition of Eu 2+ /Mn 2+ , chromaticity coordinates of (0.31, 0.33) can be achieved under excitation at 250-440 nm. Moreover, white-light-emitting diodes were fabricated through the integration of 365 nm chips and single composition white-lightemitting phosphors (Ca 0.975 Eu 0.01 Mn 0.015 ) 9 Y(PO 4 ) 7 into a single package shows a cool white light of 7200 K, color rendering index of 76, and color coordinates of (0.30, 0.31) close to that of ideal white light can be achieved.