Synthesis optimization, photoluminescence and thermoluminescence studies of Eu3+ doped calcium aluminozincate phosphor (original) (raw)
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Calcium aluminozincate phosphor, Ca 3 Al 4 ZnO 10 (CAZ) doped with Eu 3þ has been synthesized using solidstate reaction (SSR), combustion (CS) and sol-gel (SG) methods for relatively improved luminescence performance and to optimize synthesis method. The X-ray diffraction (XRD), scanning electron microscope (SEM), photoluminescence (PL) and PL decay measurements have been recorded for the detailed investigation of the luminescence properties of the as-synthesized phosphor. The thermoluminescence (TL) spectral study has been done to estimate the trap depth of the defect centres. The XRD peaks confirm the complete matching of the diffraction peaks of the as-synthesized sample with the standard data for Ca 3 Al 4 ZnO 10. The morphology of the sample synthesized via SG method shows agglomerated particles with average particle size smaller than the samples synthesized via CS and SSR method. The detailed investigation shows significant red emission enhancement in Eu 3þ doped CAZ phosphor synthesized via SG method. The obtained results suggest that the Eu 3þ doped CAZ phosphor synthesized via SG method could be a great choice as red emitter for applications in solid state lighting.
Luminescence Properties of Calcium Aluminate Phosphors
2019
Luminescence properties of CaAl2O4 were studied. Rare earth Eu2+ doped alkaline earth aluminate CaAl2O4 phosphor was prepared by combustion synthesis using urea as a fuel at 600 °C. It was found that firstly the TL intensity increases with increase in UV irradiation time and it attains a maximum value for 15 minute irradiation time. TL intensity decreases with further increase in irradiation time. In photoluminescence (PL) spectrum, a broad emission peak of Eu2+ ion was observed in blue region at 441 nm, under 363 nm excitation due to transition from the 4f65d1 to the 4f7 configuration of the Eu2+ ion. Optimum intensity of photoluminescence (PL) was found to be 0.05 mol% concentration of Eu2+.
Journal of Science: Advanced Materials and Devices, 2017
Series of CaZrO 3 :xEu 3+ (x = 1.0, 2.0, 3.0, 4.0 and 5.0 mole%) phosphors was successfully prepared by the solid state reaction method. The crystal structure of sintered phosphors was hexagonal phase with space group of Pm-3m. Near ultraviolet (NUV) excitation, emission spectra of CaZrO 3 :xEu 3+ phosphors was composed of sharp line emission associated with the transitions from the excited states 5 D 0 to the ground state 7 F j (j = 0, 1, 2, 3, 4) of Eu 3+. The results indicated that the CaZrO 3 :xEu 3+ might become an important orange-red phosphors candidate for white light emitting diodes (WLEDs) with near-UV LED chips. The peak of mechanoluminescence (ML) intensity increases linearly with increasing impact velocity of the moving piston, which suggests that sintered phosphors can be useful as a stress sensor.
Luminescence Properties of CaAl2O4:Eu3+, Gd3+ Phosphors Synthesized by Combustion Synthesis Method
Acta Physica Polonica A, 2017
CaAl2O4:Eu 3+ (1 mol.%) co-doped with varying concentration of Gd 3+ (1, 2, 5, and 10 mol.%) were prepared by combustion synthesis method at 600 • C and further annealed at 1000 • C. All the compositions were investigated for their structural and photoluminescence properties. It was observed that both states of europium i.e. Eu 3+ and Eu 2+ were present and ratio of these states changes on heating at 1000 • C. The materials synthesized at 600 • C showed high intense peak around 440 nm due to presence of Eu 2+ and less intense peaks in the red region which were due to presence of Eu 3+. On annealing the compounds at 1000 • C, intensity of peak around 440 nm decreases and intensity of peaks in the red region increases significantly. The 5 D0 → 7 F3 transition due to Eu 3+ at 657 nm appears as the highest intensity peak. All co-doped samples annealed at 1000 • C showed the higher intensity than the mono doped sample which is due to energy transfer from the Gd 3+ to Eu 3+. The second rare-earth ion (Gd 3+) acts as sensitizer and enhances the photoluminescence intensity. The X-ray diffraction spectra reveal the monoclinic phase of CaAl2O4 in all the samples which showed that Eu 3+ and Gd 3+ do not change the crystalline structure of calcium aluminate.
In this work, we report on the synthesis and photoluminescence (PL) properties of rare earth (Eu3þ, Sm3þ and Pr3þ) doped double perovskite tungstate Ca2ZnWO6 phosphor. The phosphors were synthesized by two step modified solid state method. Phase purity and formation of phosphor were confirmed byXRDtechnique. PL spectra of Eu3þ,Sm3þ and Pr3þ doped phosphor show intense emission peaks in red region at 615, 604 and 650 nm respectively, upon the visible excitation of 466 nm (Eu3þ), 410 nm(Sm3þ) and 491nm(Pr3þ). The CIE coordinates of the phosphors are in the yellow (Sm3þ doped sample) and orange (Eu3þ and Pr3þ doped sample) regions near the edge of color space which confirms their applicability in LEDs.
Journal of Luminescence, 2013
A combustion synthesis method has been developed for synthesis of Eu 2+ doped CaAlSiN3 phosphor and its photoluminescence properties were investigated. Ca, Al, Si, and Eu2O3 powders were used as the Ca, Al, Si and Eu sources. The addition of NaN3, NH4Cl and Si3N4 powders was found to increase significantly the product yield. These powders were mixed and pressed into a compact, which was then wrapped up with an igniting agent (i.e., Mg+Fe3O4). The compact was ignited by electrical heating under a N2 pressure of ≤1.0 MPa. Effects of these experimental parameters on the product yield were investigated and a reaction mechanism was proposed. The synthesized CaAlSiN3:Eu 2+ phosphor absorbs light in the region of 200-600 nm and shows a broad band emission in the region of 500-800 nm due to the 4f 6 5d 1 → 4f 7 transition of Eu 2+. The sample doped with Eu 2+ at the optimized molar ratio of 0.04 is efficiently excited by the blue light (460 nm) and generates emission peaking at ~650 nm with peak emission intensity ~106% of a commercially available phosphor, YAG:Ce 3+ (P46-Y3).The internal quantum efficiency of the synthesized phosphor was measured to be 71%, compared to 69% of the YAG:Ce 3+ (P46-Y3).
Synthesis and characterization of CaAlxOy:Eu2+ phosphors prepared using solution-combustion method
Journal of Rare Earths, 2010
Europium-doped calcium aluminate (CaAl x O y :Eu 2+ ) phosphors were obtained at low temperatures (500 ºC) by the solution -combustion of corresponding metal nitrate-urea solution mixtures. The particle size and morphology and the structural and luminescent properties of the as-synthesized phosphors were examined by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), Auger spectroscopy, transmission electron spectroscopy (TEM) and photoluminescence (PL). It was found that the Ca:Al molar ratios showed greatly influence not only on the particle size and morphology, but also on their PL spectra and structure. With the Ca: Al molar ratios increasing from 6:100 to 26:100, the structure of as-synthesized phosphor changed from CaAl 12 O 19 to monoclinic CaAl 2 O 4 and the dominant emitting light from red to blue, implying that the oxidation state of doped europium ions changed from trivalent to divalent due to the structure variation of host lattice. A blue phosphor with almost pure phase can be easily prepared by solution combustion method with suitable Ca:Al molar ratio.
Synthesis and luminescence properties OF Ca5(PO4)3Cl:Eu2+ phosphor for solid state lighting
St. Petersburg State Polytechnical University Journal. Physics and Mathematics, 2016
A novel method to prepare Eu 2 + doped chlorapatite phosphor Ca 5 (PO 4) 3 Cl useful for solid state lighting has been given in this paper. The phosphor was synthesized by the Pechini (citrate gel) method which turned out to be more efficient than the conventional high temperature solid state reaction. The results of the photoluminescence (PL) investigation revealed that it was possible to efficiently excite the phosphor by a UV-visible light from 220 to 430 nm; the phosphor exhibited a bright blue emission at the wavelength λ em =456 nm for the excitation wavelength λ ex =350 nm of near-ultraviolet light. The developed phosphor emits in blue and, hence, could provide one of the three (RGB) primary color components in a phosphor-converted LED-producing white light.
Science of Advanced Materials, 2013
Novel red-emitting phosphors, Eu 3+ -doped Y 2 CaZnO 5 (YCZ), were synthesized by modified urea assisted sol-gel combustion method. The X-ray diffraction analysis indicates the uniform formation of single-phase triclinic YCZ nanoparticles even when the concentration of Eu 3+ ions is as high as 50 mol%. TEM measurements revealed that the particles have uniform size distributions in the range of 10-30 nm. Luminescence properties have been characterized using photoluminescence excitation, emission spectra and decay time measurements. A strong charge transfer band (CTB) at around 250 nm is observed which is due to the Eu O interaction in the host along with the 4f -4f excitation bands due to Eu 3+ ions in UV and blue regions. The excitation bands at 395 nm 7 F 0 → 5 L 6 and 465 nm 7 F 0 → 5 D 2 are found to be stronger than the CTB for Eu 3+ :YCZ nanophosphor, which match very well with the emission wavelength of commercial InGaN blue LED chip. Upon excitation to these wavelengths, a bright red emission from the 5 D 0 level of Eu 3+ ion is observed with CIE chromaticity coordinates (0.65, 0.34), which are found to be very close to the National Television System Committee (NTSC) for red phosphor (0.67, 0.33).
Journal of Luminescence, 2009
The photoluminescence (PL) emission and excitation behavior of red-emitting Eu 0.1 Gd x La 1.9Àx TeO 6 (0.02pxp0.1) powder phosphors is reported. Three dominant bands centered at 395, 466 and 534 nm characterized the excitation spectrum. Under the excitation of 395 nm UV light, the emission spectrum exhibits an intense peak centered at 616 nm corresponding to the 5 D 0 -7 F 2 transition of Eu 3+ . Because the f-f transitions are located in the wavelength range of blue or near-UV range, optimized phosphor, Eu 0.10 Gd 0.08 La 1.82 TeO 6 , is a promising material for solid-state lighting based on GaN LEDs applications.