Electroluminescence of SrAl2O4:Eu2+ phosphor (original) (raw)
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Physica B-condensed Matter
Long persistent SrAl2O4:Eu2+ phosphors co-doped with Dy3+ were prepared by the solid state reaction method. The main diffraction peaks of the monoclinic structure of SrAl2O4 were observed in all the samples. The broad band emission spectra at 497 nm for SrAl2O4:Eu2+, Dy3+ were observed and the emission is attributed to the 4f65d1 to 4f7 transition of Eu2+ ions. The samples annealed at 1100–1200 °C showed similar broad TL glow curves centered at 120 °C. The similar TL glow curves suggest that the traps responsible for them are similar. The long afterglow displayed by the phosphors annealed at different temperatures, may be attributed to the Dy3+ ions acting as the hole trap levels, which play an important role in prolonging the duration of luminescence.
Functional Materials Letters, 2013
The aim of the present investigation was to develop a phosphor to solve the flickering luminescence of alternating current (AC) lightemitting diodes (LED) by compensating the dark duration with appropriately persistent luminescence. The phosphor SrAl 2 O 4 :Eu 2þ co-doped with Y 3þ or Dy 3þ was synthesized via solid-state reaction with H 3 BO 3 as flux. The crystal structure and morphology were characterized by using X-ray diffraction (XRD) and Scanning Electron Microscope (SEM), respectively. The photoluminescence spectra were collected with a fluorescence spectrometer. The results demonstrated that appropriate amount of Y 3þ or Dy 3þ doped was beneficial to suppress the by-product of Sr 4 Al 14 O 25 which easily co-existed with the SrAl 2 O 4 phase brought by the flux of H 3 BO 3 . However, too much Y 3þ or Dy 3þ doped resulted in the formation of another impurity phase, i.e., the yttrium aluminum garnet of Y 3 Al 5 O 12 and Dy 3 Al 5 O 12 . Comparatively, the doped Dy 3þ was more helpful in prolonging the persistent luminescence, while Y 3þ was more efficient in enhancing luminescence intensity. To demonstrate the feasibility of the phosphor applied in AC LEDs, a nearly white AC LED was fabricated by coating the phosphor on a blue AC LED chip. The persistent luminescence was radiated from the AC LED device after turning power off. Moreover, the effect of the phosphor on compensating the AC LED dark duration through persistent luminescence was revealed by using the Keyence VW-9000 High-speed Microscope for the first time.
Wet chemical synthesis and photoluminescence study of SrAl2S4:Eu2+,Ce3+ phosphor
2019
Yu et al described the structural and luminescent properties of SrAl2S4: Eu 2+ and synthesized this phosphor by the evacuated sealed quartz ampoule method. Le Thi et al investigated SrAl2S4:Eu 2+ by solid state method. These methods are rather tedious, and require special apparatus. We have described a wet chemical co-precipitation procedure for synthesizing highly efficient Eu 2+ ,Ce 3+ activated phosphors with strong excitation in nUV region. This method does not require the H2S gas flow during synthesis and comparatively easy to handle .We successfully prepared SrAl2S4:Eu 2+ , SrAl2S4:Ce 3+ powders by this method. Synthesis and photoluminescence characterization of these phosphors are described in this paper. The SrAl2S4:Eu 2+ phosphor shows intense emission in the green region peaking around 515 nm. The excitation covers broad range from 220-430 nm peaking at 335nm. The SrAl2S4:Ce 3+ shows emission wavelength of 380 nm for 324nm excitation. SrAl2S4: Eu 2+ emission provides good CIE color coordinates(X= 0.209, Y= 0.548) for green component in display applications.
Physica B: Condensed …, 2011
Long persistent SrAl 2 O 4 :Eu 2 þ phosphors co-doped with Dy 3 þ were prepared by the solid state reaction method. The main diffraction peaks of the monoclinic structure of SrAl 2 O 4 were observed in all the samples. The broad band emission spectra at 497 nm for SrAl 2 O 4 :Eu 2 þ , Dy 3 þ were observed and the emission is attributed to the 4f 6 5d 1 to 4f 7 transition of Eu 2 þ ions. The samples annealed at 1100-1200 1C showed similar broad TL glow curves centered at 120 1C. The similar TL glow curves suggest that the traps responsible for them are similar. The long afterglow displayed by the phosphors annealed at different temperatures, may be attributed to the Dy 3 þ ions acting as the hole trap levels, which play an important role in prolonging the duration of luminescence.
SrAl2O4:Eu2+ (1%) luminescence under UV, VUV and electron beam excitation
Optical Materials, 2018
This paper reports the luminescence properties of nanosized SrAl 2 O 4 :Eu 2þ (1%) phosphors. The samples were prepared by combustion method at 600 C, followed by annealing of the resultant combustion ash at 1000 C in a reductive (Ar þ H 2) atmosphere. X-ray diffraction (XRD), photo luminescence (PL) and cathodoluminescence (CL) analysis and thermal stimulated luminescence (TSL) method were applied to characterize the phosphor. For the first time a peak at 375 nm was observed in CL spectra of SrAl 2 O 4 :Eu 2þ (1%) nanophosphors. Luminescence excitation spectra analysis have shown that this peak is related to crystal defects. Also in TSL curve one strong peak was observed in the region above room temperature (T ¼ 325 K), which is attributed to lattice defects, namely oxygen vacancies. A green LED was fabricated by the combination of the SrAl 2 O 4 :Eu 2þ (1%) nanosized phosphor and a 365 nm UV InGaN chip.
Korean Journal of Chemical Engineering, 2003
− − − −SrAl 2 O 4 : (Eu 2+ , Dy 3+) phosphor was prepared by solid state reaction. B 2 O 5 as a flux was added in SrAl 2 O 4 : (Eu 2+ , Dy 3+) in order to accelerate a solid state reaction. In this paper, the effects of B 2 O 3 on the crystal structure and the phosphorescent properties of the material have been evaluated. The synthesized phosphor exhibited a broad band emission spectrum peaking at 520 nm, and the spectrum peak showed little effect by the B 2 O 3 contents. The maximum afterglow intensity of the SrAl 2 O 4 : (Eu 2+ , Dy 3+) phosphor was obtained at the B 2 O 3 content of 5%. Adding the B 2 O 3 caused uniform distortion to the crystal structure of the phosphor and resulted in reducing the lengths of a and c axes and β angle of the SrAl 2 O 4 crystal. The uniform distortion was accompanied with crystal defects which can trap the holes generated by the excitation of Eu 2+ ions. The afterglow characteristic of the SrAl 2 O 4 : (Eu 2+ , Dy 3+) phosphor was thus enhanced.
SrAl2O4: Eu2+, Dy3+ phosphors derived from a new sol–gel route
Microelectronics Journal, 2004
The SrAl 2 O 4 : Eu 2þ , Dy 3þ phosphor powders were prepared by a new sol-gel method using aluminum isopropoxide and strontium acetate as precursors. The sol -gel process and the structure of the phosphor powders were investigated by means of DSC-TG and XRD. It was found that the single-phase SrAl 2 O 4 was formed at 900 8C, which is 300 8C lower than that required for the conventional solid-state reaction. The particle morphology, photoluminescence and afterglow properties of the phosphors were studied in this article. q
2015
Thin films of Eu2þ doped and Dy3þ ,Nd3þ co-doped Strontium Aluminate (SrAl2O4:Eu 2þ ,Dy3þ ,Nd3þ) phosphors were grown on Si(100) substrates by a pulsed laser deposition (PLD) technique using a 266 nm Nd:YAG pulsed laser under varying substrate temperature and the working atmosphere during the film deposition process. The effect of substrate temperatures and argon partial pressure on the structure and luminescence properties of the as-deposited SrAl2O4:Eu ,Dy3þ ,Nd3þ phosphor thin films were analysed. XRD patterns showed that with increasing substrate temperature and argon partial pressure the peaks in the direction (220) shifted to the lower 2-theta angles. Photoluminescence (PL) data collected in air at room temperature revealed a slight shift in the peak wavelength of the PL spectra observed from the thin films when compared to the PL spectra of the phosphor in powder form, which is probably due to a change in the crystal field. The PL intensity of the samples was highest for 100 ...
Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, 2010
Thin films of SrAl 2 O 4 :Eu 2+ ,Dy 3+ phosphor were deposited on silicon ͓Si ͑100͔͒ substrates using a 248 nm KrF pulsed laser. Deposition parameters, such as substrate temperature, pulse repetition rate, number of laser pulses, and base pressure, were varied during the film deposition process. Based on the x-ray diffraction data, all the films were amorphous but were emitting visible light when excited by a monochromatic xenon lamp. The chemical composition and the stoichiometry of the films determined by the Rutherford backscattering spectroscopy were consistent with the commercial SrAl 2 O 4 :Eu 2+ ,Dy 3+ powder used to prepare the films. Photoluminescence ͑PL͒ emission spectra of the films were characterized by major green emission with a maximum at ϳ520 nm and minor red emission with a maximum at 630 nm. The green and red photoluminescence at 520 and 630 nm are associated with the 4f 6 5d → 4f 7 ͑ 8 S 7/2 ͒ and 5 D 0 -7 F 2 transitions of Eu 2+ and residual Eu 3+ ions, respectively. Brighter films were shown to have relatively higher values of the root mean square surface roughness, which were determined from the atomic force microscopy data. The effects of processing parameters on the PL intensity are discussed.
The combustion synthesis method was employed for the synthesis of red-emitting monoclinic SrAl2O4:Eu 3+ phosphors. Structural characterization of annealed samples was carried out via X-ray Diffraction (XRD). XRD patterns reveal that strontium aluminate samples were cubic spinel nanoparticles and the grain size determined by the Debye-Scherrer formula is 35.34 nm. The vibrational stretching frequencies corresponding to the composites were confirmed by FT-IR spectroscopy. The PL spectra show the strongest emission at 612 nm corresponds to the 5 D0 → 7 F2 transition of Eu 3+ , which results in bright red color emitting phosphor used for display devices and lamp industries.