Effect of bismuth ions on the photoluminescence properties of BaTiO3:Dy3+ perovskite phosphors for LEDs application

A series of (Ba_1?xBi_0.01)TiO₃ doped with Dy³⁺ ions of varying concentrations is prepared by single-step solid-state reaction that promulgates solid-state lighting device applications. The cubic phase perovskite structure of the prepared samples is determined by the powder X-ray diffraction results. The emission spectra show evidence of intensive peaks at 572 nm attributing to the ⁴F_9/2 to ⁶H_15/2 of Dy³⁺ ions. Dy³⁺-doped phosphors (Ba_1?xBi_0.01) TiO₃: xDy³⁺ (x?=?0, 0.01, 0.03, 0.05 and 0.07) exhibit yellow emission, and the highest intensity of emission demarcates the optimum concentration of Ba_1?xBi_0.01TiO₃:0.05Dy³⁺. SEM studies to assess the surface morphologies alongside the elemental analyses from energy-dispersive spectroscopy (EDS) extensively for optimal concentration have been ventured. The Commission International De I-Eclairage (CIE) and correlated colour temperature (CCT) analyses authenticate the present phosphor genuine for fabricating light emitting diodes.

     

Synthesis and characterizations of Dy3+ doped Sr3Al2O6:Eu2+ powder phosphors through citric acid precursor

Sr₃Al₂O₆:Eu²⁺, Dy³⁺ phosphors were synthesized by the polymer precursor method. The X-ray powder diffraction patterns show that the samples have a cubic structure with a space group of Pa3. In the excitation spectrum, the phosphors show a wide absorption in the UV region from 250 to 450 nm, which corresponds to the crystal field splitting of the Eu²⁺ d-orbital. All the emission spectrum of Sr₃Al₂O₆:Eu²⁺, Dy³⁺ phosphors show the broad band emission peaked at about 518 nm, which can be ascribed to the typical 4f⁶5d¹ → 4f⁷ transitions of Eu²⁺ ions. And the best dopant concentration of Dy³⁺ ions for Sr₃Al₂O₆:2 mol%Eu²⁺, xDy³⁺ phosphors is 2 mol%. The excitation wavelengths have no influences on emission peaks, but have clear influences on emission intensities.     

The comparison: photoluminescence and afterglow behavior in CaSnO<Subscript>3</Subscript>:Dy<Superscript>3+</Superscript> and Ca<Subscript>2</Subscript>SnO<Subscript>4</Subscript>:Dy<Superscript>3+</Superscript> phosphors

This paper reports the comparison of photoluminescence and afterglow behavior of Dy³⁺ in CaSnO₃ and Ca₂SnO₄ phosphors. The samples containing CaSnO₃ and Ca₂SnO₄ were prepared via solid-state reaction. The properties have been characterized and analyzed by utilizing X-ray diffraction (XRD), photoluminescence spectroscope (PLS), X-ray photoelectron spectroscopy (XPS), afterglow spectroscopy (AS) and thermal luminescence spectroscope (TLS). The emission spectra revealed that CaSnO₃:Dy³⁺ and Ca₂SnO₄:Dy³⁺ phosphors showed different photoluminescence. The Ca₂SnO₄:Dy³⁺ phosphor showed a typical ⁴F_9/2 to ⁶H_j energy transition of Dy³⁺ ions, with three significant emissions centering around 482, 572 and 670 nm. However, the CaSnO₃:Dy³⁺ phosphor revealed a broad T₁ → S₀ transitions of Sn²⁺ ions. The XPS demonstrate the existence of Sn²⁺ ions in CaSnO₃ phosphor caused by the doping of Dy³⁺ ions. Both the CaSnO₃:Dy³⁺ and Ca₂SnO₄:Dy³⁺ phosphors showed a typical triple-exponential afterglow when the UV source switched off. Thermal simulated luminescence study indicated that the persistent afterglow of CaSnO₃:Dy³⁺ and Ca₂SnO₄:Dy³⁺ phosphors was generated by the suitable electron or hole traps which were resulted from the doping the calcium stannate host with rare-earth ions (Dy³⁺).     

Luminescence properties of Na3SrB5O10:Dy3+ plate-like microstructures for solid state lighting applications

A series of novel plate-like microstructure Na₃SrB₅O₁₀ doped with various Dy³⁺ ions concentration have been synthesized for the first time by solid-state reaction (SSR) method. X-ray diffraction (XRD) results demonstrated that the prepared Na₃SrB₅O₁₀:Dy³⁺ phosphors are single-phase pentaborates with triclinic structure. The plate-like morphology of the phosphor is examined by Field emission scanning electron microscopy (FE-SEM). The existence of both BO₃ and BO₄ groups in Na₃SrB₅O₁₀:Dy³⁺ phosphors are identified by Fourier transform infrared (FT-IR) spectroscopy. Upon excitation at 385 nm, the PL spectra mainly comprising of two broad bands: one is a blue light emission (∼486 nm) and another is a yellow light emission (∼581 nm), originating from the transitions of ⁴F_9/2 → ⁶H_15/2 and ⁴F_9/2 → ⁶H_13/2 in 4f⁹ configuration of Dy³⁺ ions, respectively and the optimized dopant concentration is determined to be 3 at.%. Interestingly, the yellow-to-blue (Y/B) emission integrated intensity ratio is close to unity (0.99) for 3 at.% Dy³⁺ ions, suggesting that the phosphors are favor for white illumination. Moreover, the calculated Commission International de l’Eclairage (CIE) chromaticity coordinates of Na₃SrB₅O₁₀:Dy³⁺ phosphors shows the values lie in white light region and the estimated CCT values are located in cool/day white light region.     

Thermally stimulated luminescence and photoluminescence investigations of Eu3+ and Eu2+ doped SrBPO5

Thermally stimulated luminescence (TSL) investigations of SrBPO₅:Eu^3?+ and SrBPO₅:Eu^2?+ phosphors were carried out in the temperature range of 300–650 K. In order to characterize the phosphors, X-ray diffraction and photoluminescence (PL) techniques were used. The emission spectrum of air heated SrBPO₅:Eu^3?+ phosphor exhibited emission bands at 590, 614, 651 and 702 nm under 248 nm excitation, assigned to transitions of Eu^3?+ ion. In phosphor prepared in reducing (Ar + 8% H₂) atmosphere, a broad emission band due to Eu^2?+ ranging from 350 to 400 nm was observed with 340 nm excitation. EPR studies have confirmed the presence of Eu^2?+ ions in the samples prepared in reducing atmosphere. TSL glow curve of SrBPO₅:Eu^3?+ had shown intense peaks around 397, 510, 547 K and a weak peak around 440 K whereas in case of SrBPO₅:Eu^2?+ system, glow peaks at 414, 478 and weak peak at 516 nm were observed. The shift in TSL glow pattern can be attributed to stabilization of different oxidation states of the dopant ion in the host lattice. Apart from this, TSL trap parameters such as trap depth and frequency factor were determined. Spectral characteristics of TSL emission have shown that Eu^3?+?/Eu^2?+ ion acts as the luminescent centre in the respective phosphors.     

Powder synthesis and white light-emitting properties of Eu3+ co-doped K2CaP2O7:Dy3+ phosphors with energy transfer between Dy3+ and Eu3+

A series of white-emitting K₂CaP₂O₇:Dy³⁺ and K₂CaP₂O₇:Dy³⁺, Eu³⁺ phosphors were synthesized via a solid-state method, and Eu³⁺ was co-doped in K₂CaP₂O₇:Dy³⁺ to improve its white light performance. The influences of preparation temperature and Dy³⁺/Eu³⁺ concentration on the crystal structure and photoluminescence characteristics were investigated. XRD results indicate that K₂CaP₂O₇:Dy³⁺ samples prepared above 700 °C matches the standard K₂CaP₂O₇ phase. Under excitation of 349 nm, K₂CaP₂O₇:Dy³⁺ phosphor exhibited characteristic emission peaks at 487 nm (blue) and 579 nm (yellow), and white emission was realized through combining these blue and yellow emissions. After co-doping Eu³⁺ ions, the co-luminescence of Dy³⁺/Eu³⁺ with energy transfer between Dy³⁺and Eu³⁺ were demonstrated. The chromaticity of white light was controlled by changing the ratio of Dy³⁺/Eu³⁺ concentrations, which lead to a warm white light. Therefore, the results indicate that K₂CaP₂O₇:Dy³⁺, Eu³⁺ powders have a potential application in w-LEDs as single-component white-emitting phosphor.     

Tuning the luminescence color and enhancement of afterglow properties of Sr(4−x−y)CaxBayAl14O25:Eu,Dy phosphor by adjusting the composition

Color point tuning is an important challenge for improving the practical applications of various displays, especially there are very limited white color single hosts that emits in the white spectrum. In this paper, the possibility of color tuning by substituting part of host lattice cation (Sr²⁺ ions) by Ca²⁺ or Ba²⁺ ions in an efficient strontium aluminate phosphor, Sr₄Al₁₄O₂₅:Eu²⁺,Dy³⁺, is reported and found to be very promising for displays. A detail study by replacing part of Sr²⁺ with Ca²⁺ or Ba²⁺ has been investigated. X-ray diffraction study showed that crystal structure of Sr₄Al₁₄O₂₅ is preserved up to 20 mol of Ca²⁺ ion exchange while it is limited to 10 mol of Ba²⁺ ions exchange. Substantial shift in the emission band and color were observed by substitution of Sr²⁺ by Ca²⁺ or Ba²⁺ ions. A bluish-white emission and afterglow was observed at higher Ca²⁺ ions substitution. Further, partial Ca²⁺ substitutions (up to 0.8 mol) resulted in enhanced afterglow of Sr₄Al₁₄O₂₅:Eu²⁺,Dy³⁺ phosphor. However, Ba²⁺ substitution decreased the fluorescence as well afterglow of the Sr₄Al₁₄O₂₅:Eu²⁺,Dy³⁺ phosphor significantly. The enhanced phosphorescence by partial Ca²⁺ substitution is explained on the basis of increased density of shallow traps associated with higher solubility of Dy³⁺ ions in to the host lattice due to equivalent size of Ca²⁺ and Dy³⁺ ions. Thus, Ca²⁺ substitution in the Sr₄Al₁₄O₂₅:Eu²⁺,Dy³⁺ phosphor is a promising method for tuning the emission color and improving the afterglow intensity of the phosphor.     

Molten salt synthesis and photoluminescence properties of novel red emitting phosphors Ba5(VO4)3Cl:Eu3+,K+

A series of Ba₅(VO₄)₃Cl:Eu³⁺,K⁺ phosphors have been synthesized by the molten salt synthesis method. The crystalline structure, morphology, photoluminescence properties and lifetimes were characterized using X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM) and photoluminescence spectroscopy, respectively. XRD indicates that the Ba₅(VO₄)₃Cl:Eu³⁺,K⁺ phosphors are synthesized successfully via molten salt method. SEM image demonstrates that the obtained phosphors have hexagonal polyhedron morphology. The photoluminescence spectra reveal that the as-prepared phosphors exhibit a bright red emission under the excitation of blue or near ultraviolet light. The concentration quenching was also investigated, and the dipole–dipole interaction is responsible for the concentration quenching of fluorescence emission of Eu³⁺ ions in Ba₅(VO₄)₃Cl phosphor. The present work suggests that the Ba₅(VO₄)₃Cl:Eu³⁺,K⁺ phosphors would be a potential candidate for light emitting devices.     

Single-component and white light-emitting phosphor BaAl2Si2O8: Dy3+, Eu3+ synthesis,luminescence, energy transfer,and tunable color

A series of Dy³⁺ - Eu³⁺ co-doped BaAl₂Si₂O₈ phosphors were prepared via the conventional solid-state reaction method. Their crystal structure, luminescent characteristic and lifetime were investigated. The optimum doping concentrations of Dy³⁺and Eu³⁺ are both 0.05 for Dy³⁺ or Eu³⁺ singly doped BaAl₂Si₂O₈. Furthermore, BaAl₂Si₂O₈: 0.05Dy³⁺ and BaAl₂Si₂O₈: 0.05Eu³⁺ emits yellow and red light. The emission color of BaAl₂Si₂O₈: Dy³⁺, Eu³⁺ could be tuned from yellow to white due to the energy transfer. This energy transfer from Dy³⁺ to Eu³⁺ was confirmed and investigated by photoluminescence spectra and the decay time of energy donor Dy³⁺ ions. With constantly increasing Eu³⁺ concentration, the energy transfer efficiency from Dy³⁺ to Eu³⁺ in BaAl₂Si₂O₈ host increased gradually and reached as high as 81%, the quantum yield was about 47.43%. BaAl₂Si₂O₈: Dy³⁺, Eu³⁺ phosphors can be effectively excited by UV (about 348 nm) light and emit visible light from yellow to white by altering the concentration ratio of Dy³⁺ and Eu³⁺, indicating that the phosphors have potential applications as a white light-emitting phosphor for display and lighting.     

Color-tunable emission and energy transfer studies in GdOBr:Ce3+ Dy3+ phosphor

Color-tunable blue to bluish white-emitting Ce³⁺/Dy³⁺ co-doped GdOBr phosphors have been synthesized by the conventional solid-state method. The phase structures, luminescent properties and energy transfer process were discussed in detail. Broad-band absorption originating from the f-d transition of Ce³⁺ can be found for the as-prepared GdOBr:Ce³⁺,Dy³⁺ phosphor, and color-tunable blue to bluish white emission can be realized owing to the energy transfer between Ce³⁺ and Dy³⁺. The energy transfer mechanism is demonstrated to be the dipole–dipole process. The energy transfer efficiency increases with increasing Dy³⁺ concentrations. The results indicate that Ce³⁺/Dy³⁺-activated GdOBr phosphors may be potential for phosphor-converted white-light UV-LEDs.     

Green emission enhancement of Ba2SiO4:Eu2+ phosphor via Gd co-doping and charge compensation

A series of new green-emitting Ba_2?x?2ySiO₄:xEu²⁺, yGd³⁺, yR⁺ (R = Li, Na or K) phosphors were synthesized by the solid-reaction method. X-ray diffraction (XRD) and fluorescence spectrophotometer are utilized to characterize the crystal structure and luminescence properties of the as-synthesized phosphors, respectively. The XRD patterns reveal that the doping of Gd³⁺, Eu²⁺ and R⁺ ions have no significant influence on the Ba₂SiO₄ phase. The green emission of Eu²⁺ ion associated with 4f⁶5d¹ → 4f⁷ can be obtained by 396 nm UV excitation source, which match well with the emission wavelength of UV-LEDs chip (380–420 nm). Moreover, the effect of charge compensator ions (Li⁺, Na⁺ or K⁺) on the luminescence intensity of (Ba, Gd)₂SiO₄:Eu²⁺ phosphors were also investigated. When introducing the Li⁺ ions into the (Ba, Gd)₂SiO₄ host lattices, the as-prepared phosphors show the strongest emission. The emission intensity of Ba_1.95SiO₄:0.04Eu²⁺, 0.005Gd³⁺, 0.005Li⁺ is about 1.39 times than that of Ba_1.96SiO₄:0.04Eu²⁺. Furthermore, the mechanism of energy transfer and concentration quenching of Ba_1.982?xSiO₄:xEu²⁺, 0.009Gd³⁺, 0.009Li⁺ phosphors are also discussed.     

Photoluminescence properties of Eu doped Ba2ZnS3 phosphor for white light emitting diodes

The synthesis and photoluminescence properties of novel Eu²⁺ doped Ba₂ZnS₃ phosphors for white light emitting diodes (LEDs) are reported. Diffuse reflection spectra of Ba₂ZnS₃ host and synthesized phosphors have been measured. The excitation spectra of synthesized phosphors consist of three broad bands between 250 nm and 550 nm and are consistent with the diffuse reflectance spectra. The emission spectra show the characteristic 4f⁶5d¹ → 4f⁷ transition of Eu²⁺ ion and there exists efficient energy transfer from host to Eu²⁺ ions when excited by 350-nm light. The dependence of emission spectra on temperature is also measured; the possible reasons applied to explain the experimental results are also discussed. The fluorescence lifetime of Eu²⁺ in Ba_1.995ZnS₃:0.005Eu²⁺ is measured and the values are 1.49 and 23.4 μs.     

Luminescence properties and energy transfer studies of a color tunable BaY2Si3O10:Tm3+,Dy3+ phosphor

A series of color-tunable and white light emitting phosphors BaY₂Si₃O₁₀:Tm³⁺,Dy³⁺ were synthesized by a high temperature solid-state reaction, and their phase structure, photoluminescence properties, and energy transfer processes between rare-earth ions were investigated in detail. Upon UV excitation, white light emission depending on dopant concentrations could be achieved by integrating a blue emission band located at 458 nm and an orange one located at 576 nm attributed to Tm³⁺ and Dy³⁺ ions, respectively. In addition, the energy transfer process between Tm³⁺ and Dy³⁺ ions was demonstrated to be a resonant type via a dipole–quadrupole mechanism. Preliminary studies showed that the phosphor might be promising as a single-phased white-light-emitting phosphor for UV chip pumped white-light LEDs.     

Conversion of green emission into white light in Gd2O3 nanophosphors

Gd₂O₃ nanophosphors were prepared by combustion synthesis with and without doping of Dy³⁺ ions. The X-ray powder diffraction patterns indicate that as-prepared Gd₂O₃ and 0.1 mol% Dy₂O₃ doped Gd₂O₃ nanophosphors have monoclinic structures. The transmission electron microscope (TEM) studies revealed that the as-prepared phosphors had an average crystallite sizes around 37 nm. The excitation and emission properties have been investigated for Dy³⁺ doped and undoped Gd₂O₃ nanophosphors. New emission bands were observed in the visible region for Gd₂O₃ nanophosphors without any rare earth ion doping under different excitations. A tentative mechanism for the origin of luminescence from Gd₂O₃ host was discussed. Emission properties also measured for 0.1 mol% Dy³⁺ doped Gd₂O₃ nanophosphors and found the characteristic Dy³⁺ visible emissions at 489 and 580 nm due to ⁴F_9/2 → ⁶H_15/2 and ⁴F_9/2 → ⁶H_13/2 transitions, respectively. The chromaticity coordinates were calculated based on the emission spectra of Dy³⁺ doped and undoped Gd₂O₃ nanophosphors and analyzed with Commission Internationale de l'Eclairage (CIE) chromaticity diagram. These nanophosphors exhibit green color in undoped Gd₂O₃ and white color after adding 0.1 mol% Dy₂O₃ to Gd₂O₃ nanophosphors under UV excitation. These phosphors could be a promising phosphor for applications in flat panel displays.     

Effects of excitation wavelength and Y3+ content on luminescent properties of YMO4:Dy3+ (M = V,P) phosphors induced by ultraviolet excitation

Y_0.99VO₄:0.01Dy³⁺, Y_0.99PO₄:0.01Dy³⁺ and Y_xVO₄:0.01Dy³⁺ phosphors were synthesized by chemical co-precipitation method. All the samples were characterized by X-ray powder diffraction (XRD) and photoluminescence spectroscopy. XRD results show that the samples only have single tetragonal structure and the crystallinity of Y_0.99VO₄:0.01Dy³⁺ phosphor is higher than that of Y_0.99PO₄:0.01Dy³⁺ phosphor when the heat treatment process is same. Photoluminescence excitation spectra results show that the Y_0.99VO₄:0.01Dy³⁺ and Y_0.99PO₄:0.01Dy³⁺ phosphors can be efficiently excited by ultraviolet light from 250 nm to 380 nm, the former have a wide Dy³⁺–O^2? charge transfer band ranging from 260 nm to 350 nm including a peak at 310 nm, the latter have four peaks at 294 nm, 326 nm, 352 nm and 365 nm. Emission spectra of all the samples exhibit a strong blue emission (483 nm) and another strong yellow emission (574 nm). Moreover, the yellow-to-blue emission intensity ratio and color temperature of emission of Dy³⁺ are strongly related to excitation wavelength in Y_0.99PO₄:0.01Dy³⁺ phosphor, but it is almost not in Y_0.99VO₄:0.01Dy³⁺ phosphor. For Y_xVO₄:0.01Dy³⁺ (x = 0.94, 0.97, 0.99, 1.01, 1.03) phosphors, with increasing value of x, the body color of phosphor changes from yellow to white and the strongest peak in excitation spectra shifts a little to shorter wavelength. It is detrimental to luminous intensity when Y³⁺ content deviate stoichiometric ratio, but the influence of Y³⁺ on the color temperature of emission of YVO₄:Dy³⁺ phosphor is slight.     

Synthesis and luminescent properties of Eu3+ and Dy3+ doped BiPO4 phosphors for near UV-based white LEDs

The phosphors BiPO₄:Eu³⁺ co-doped with Dy³⁺ were synthesized by the conventional solid-state reaction method. XRD and scanning electron microscopy results showed that the crystalline phase of the samples BiPO₄:Eu³⁺ transforms from high-temperature monoclinic phase to low-temperature monoclinic phase with the increase of Dy³⁺ concentration. The photoluminescence properties of the samples showed that the colors shifting from red–orange area to blue–green area are close to those of ideal white light by readjusting the doping concentration ratio of Eu³⁺ and Dy³⁺. The Eu³⁺and Dy³⁺ doped BiPO₄ phosphors may be potential applications in white light near-UV light-emitting diodes.     

Luminescent properties of single-phase Ba<Subscript>2</Subscript>P<Subscript>2</Subscript>O<Subscript>7</Subscript>:Tb<Superscript>3+</Superscript>, R (R = Eu<Superscript>2+</Superscript>, Ce<Superscript>3+</Superscript>) phosphors for white LED

The Ba₂P₂O₇:Tb³⁺, R (R?=?Eu²⁺, Ce³⁺) phosphors were synthesized by use of a co-precipitation method. Crystal phase, excitation and emission spectra of sample phosphors are analyzed by means of XRD and FL, respectively. The emission spectra of Ba₂P₂O₇:Ce³⁺, Tb³⁺ phosphors exhibit four linear peaks attributed to the ⁵D₄?→?⁷F_J (J?=?6–3) transition of Tb³⁺ while four broad emission bands are observed in the emission spectra of Ba₂P₂O₇:Eu²⁺, Tb³⁺ phosphors. The effects of Eu²⁺ concentration on the luminescent properties of Ba₂P₂O₇:Tb³⁺, R (R?=?Eu²⁺, Ce³⁺) are studied. Ce³⁺ affects the luminescent properties of Ba₂P₂O₇:Ce³⁺, Tb³⁺ phosphors just as the sensitizer. However, Eu²⁺ is considered both as the sensitizer and the activator in Ba₂P₂O₇:Eu²⁺, Tb³⁺ phosphors. The chromaticity coordinates of Eu²⁺ and Tb³⁺ co-doped phosphors gather around the white light field with the CCT approximate to 5000 K, indicating that the luminescent property of Ba₂P₂O₇:Eu²⁺, Tb³⁺ phosphors may approach to a desired level needed for white LED application.     

Preparation and blue–white luminescence properties of Bi3+-doped Ba5SiO4Cl6

The Ba₅SiO₄Cl₆:Bi³⁺ phosphor was synthesized by high-temperature solid-state reaction and its luminescence property was investigated. The results showed that the Bi³⁺-doped Ba₅SiO₄Cl₆ phosphors exhibited an intense blue–white light emission located at 480 nm and a broad excitation band from 230 to 340 nm. The Bi³⁺-doped Ba₅SiO₄Cl₆ phosphors can be efficiently excited by the incident light of 220–340 nm, and the emission properties of the Bi³⁺-doped Ba₅SiO₄Cl₆ samples are strongly dependent on the excitation wavelength. The emission color tunability can be obtained by changing the excitation wavelength. The visible region emission characteristics of Ba₅SiO₄Cl₆:Bi³⁺ indicates that it can potentially be used as a new efficient blue–white luminescent material.     

Optical characteristics and charge transfer band excitation of Dy3+ doped Y2O3 phosphor

Dy³⁺ ion-doped Y₂O₃ phosphors have been synthesized and characterized for structure and optical properties. Structural characterization reveals that the samples are well crystalline. The crystallinity and particle size increases as the sample is post annealed, while optical quenching entities are reduced due to which a significant enhancement in fluorescence is observed. The phosphor is efficiently excited by ultraviolet light and emits intense blue (486 nm), yellow (573 nm), red (666 nm), and near infrared (764 nm, 823 nm) light. The emission is also observed even if charge transfer band (CTB) is excited, via energy transfer from CTB to 4f levels of Dy³⁺ ion. The intensity of yellow transition band varies with a variation in concentration of Dy³⁺ ion as well as with excitation wavelength, while the intensity of other transitions remains unaffected. Thus a variation in yellow to blue color (Y/B) gives an opportunity for the development of color tunable phosphor.     

Synthesis of Long Afterglow SrAl2O4: Eu2+, Dy3+ Phosphors Through Microwave Route

A novel and fast microwave route is used for the synthesis of SrAl₂O₄: Eu²⁺, Dy³⁺ powder phosphors. Based on the XRD peaks, the powder phosphors were identified as SrAl₂O₄ phase, which is monoclinic (a = 8.4424Å, b = 8.822 Å, c = 5.1607Å, = 93.415°). Compared with those synthesized by solid-state reaction process, the phosphors show a smaller grain size (about 4.8 m). It exhibited broadband peaks in both the excitation and emission spectra. A clear blue shift occurs in the excitation and emission spectra of these phosphors compared to those synthesized by solid-state reaction process. The excitation peaks lied between 300 nm and 450 nm, and the main emission peaks lied around 507 nm. The afterglow curve shows that the initial luminescent intensity of the phosphors synthesized through microwave route decreases greatly.