Reddish-orange emission from sol-gel derived Sm3+-doped Sr2La8(SiO4)6O2 phosphors (original) (raw)
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Journal of Alloys and Compounds, 2018
Samarium (III) doped fluorapatite phosphors La 6-x Ba 4 (SiO 4) 6 F 2 : xSm 3+ (LBSF: Sm 3+) 1＜ were synthesized for the first time, via the conventional high-temperature solid-state method in the air atmosphere. The samples were measured by X-ray diffraction, scanning electron microscopy and photoluminescence spectroscopy, i.e. emission and excitation spectra, as well as luminescence decay curves. The as-prepared samples can be excited in the range from 300-500 nm, centered at 404 nm. Photoluminescence measurements showed the emission spectra are composed of four sharp peaks characteristic of Sm 3+ ions, at about 565, 603, 650 and 711 nm. The critical concentration for quenching of Sm 3+ ions in the LBSF matrix is about 0.12 mol. According to the Dexter's theory, the mechanism of energy transfer between Sm 3+ ions was considered to be dipole-quadrupole (d-q) interactions, with the critical distance calculated by the concentration quenching method to 9.89 Å. Moreover, the temperature-dependent emission spectra showed that 2＜ the as-prepared phosphors have good thermal stability, with an activation energy of about 0.161 eV. Finally, according to the CIE coordination, the phosphor exhibited reddish-orange emission. Thanks to the mentioned favorable structural and optical properties, the Sm 3+-doped La 6 Ba 4 (SiO 4) 6 F 2 phosphors have a potential application character, for the near ultraviolet white light emitting diodes.
Effects of Li + on photoluminescence of Sr 3 SiO 5 : Sm 3+ red phosphor
Chinese Physics B, 2013
The structure and photoluminescence (PL) properties of Sr 3 SiO 5 : Sm 3+ and Li +-doped Sr 3 SiO 5 : Sm 3+ red-emitting phosphors were investigated. Samples were prepared by the high-temperature solid-state method. PL spectra show that the concentration quenching occurs when the Sm 3+ concentration is beyond 1.3 mol% in Sr 3 SiO 5 : Sm 3+ phosphor without doping Li + ions. The concentration-quenching mechanism can be explained by the electric dipole-dipole interaction of Sm 3+ ions. The incorporation of Li + ions into Sr 3 SiO 5 : Sm 3+ phosphors, as a charge compensator, improves the PL properties. The lithium ions also suppress the concentration quenching in Sm 3+ with concentration increased from 1.3 mol% to 1.7 mol%.
Sol‐gel synthesis of strontium aluminate phosphor and its TL and OSL properties
Radiation Physics and Chemistry, 2019
SrAl 2 O 4 monoclinic and Sr 12 Al 14 O 33 cubic phase nanocrystals were synthesized using sol-gel route and their morphology verified with X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) to confirm the crystallinity of the samples and the crystallites nanoscale. Luminescence emissions were investigated by Optically Stimulated Luminescence (OSL) and Thermoluminescence (TL) methods in samples thermally treated at 1000 °C for 2 hours and irradiated with β particles. TL glow curve was complex with 9 individual peaks, which was analyzed by T m-T stop method, general order kinetic theory using Computerized Glow Curve Deconvolution (CGCD). A thermal transfer TL phenomenon was observed when the samples were pre-heated in T m-T stop procedure. CW-OSL decays measured at 30 o C have high intensities even in low doses region and curves were deconvoluted using general order kinetic theory suppling two components for low doses and three components for high dose.
SYNTHESIS AND CHARACTERIZATION OF SrAl 2 O 4 : Sm PHOSPHOR BY LOW TEMPERATURE SYNTHESIS
The alkaline earth aluminate phosphor SrAl 2 O 4 : Sm synthesized by solution combustion method at low temperature (550˚C) using metal nitrates with oxalyne dihydrazine as fuel. This process results in large production of phosphor with low density, can be achieved within 5 minutes when compared to other conventional methods. The synthesized product was characterized by X-Ray Diffraction studies, Scanning Electron Microscope, Thermal studies, FTIR, Atomic Force Microscopy and UV-VISIBLE. XRD confirms monoclinic phase, Scanning Eectron Microscope prove that the nano phosphor is highly voluminous and porus. Thermal behaviour shows that loss of weight is less when compared to other methods. Atomic force microscopy shows that the particle size varies with calcination temperature. The average particle size without calcination is found to be 50 to 100nm. The band gap of nano phosphor found to be 5.18ev.
Materials Chemistry and Physics, 2019
A series of reddish orange light emitting SrGdAlO 4 : Sm 3+ nanophosphor was prepared by urea aided solution combustion process. Structural features of the prepared nanophosphor were described by the powder X-ray diffraction (PXRD) together with Rietveld refinement technique. The results authenticate the existence of single phased tetragonal lattice with space group of I4/mmm (139). The highly intense peak observed in the photoluminescence emission spectra of the synthesized nanocrystalline phosphors was observed at 600 nm owing to 4 G 5/2 → 6 H 7/2 transition upon excitation by 407 nm light. The estimated energy band gap of SrGd 0.97 Sm 0.03 AlO 4 nanophosphor was found to be 5.45 eV. The critical distance value evaluated for non-radiative energy transfer comes around 17.52 Å. The main reason responsible for the observed concentration quenching phenomenon in emission intensity of the prepared nanophosphor beyond 3 mol % doping of Sm 3+ was found to be dipole-dipole (d-d) type electric multipolar interaction. The refractive index of the optimized nanophosphor (SrGd 0.97 Sm 0.03 AlO 4) comes around 1.682. The chromaticity coordinates were found to lie in the reddish-orange region of CIE (Commission Internationale De I'Eclairage) diagram. The vivid description of the photoluminescent and structural aspects validate the potential applications of synthesized nanophosphor as optical nanomaterials in phosphor converted white light emitting diodes (pc-WLEDs).
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
In this study, we have synthesized Dy 3þ activated Sr 5 (PO 4 ) 3 F (S-FAP) phosphors by sol-gel synthesis method. The synthesized phosphors were characterized by X-ray diffraction pattern (XRD), scanning electron microscopic (SEM), photoluminescence (PL) and thermoluminescence (TL) for structural, morphological and luminescent properties. Dy 3þ activated Sr 5 (PO 4 ) 3 F phosphor shows its characteristic PL emission at 481 nm and 574 nm due to 4 F 9/2 / 6 H 15/2 and 4 F 9/2 / 6 H 13/2 transitions, respectively. TL characteristics of Dy 3þ doped Sr 5 (PO 4 ) 3 F phosphors were taken after irradiation by 60 Co gamma exposure. Two separate TL peaks at 126 C and 279 C were observed in case of Dy 3þ doped phosphor. Sr 5 (PO 4 ) 3 F:Dy 3þ phosphor was irradiated within a wide range of exposure of 50 Gy to 7 kGy doses. Linearity was found up to 2 kGy and thereafter TL response saturates. Fading study was also carried out over the duration of six weeks for Sr 5 (PO 4 ) 3 F phosphor. Trapping parameters were calculated using Chen's peak shape method, initial rise method and various heating rate method. Glow curve is deconvoluted using computerized glow curve deconvolution program. TL sensitivity of Sr 5 (PO 4 ) 3 F:Dy 3þ phosphor is found to be less by a factor of 2.08 than commercially used CaSO 4 :Dy phosphor. In order to identify the defect centers formed upon g-ray irradiation in Sr 5 (PO 4 ) 3 F:Dy 3þ phosphor, EPR measurements were carried out on un-irradiated and irradiated phosphors.
Journal of Alloys and Compounds, 2016
In this study, we have synthesized Dy 3+ activated Sr 5 (PO 4) 3 F (S-FAP) phosphors by solgel synthesis method. The synthesized phosphors were characterized by X-ray diffraction pattern (XRD), scanning electron microscopic (SEM), photoluminescence (PL) and thermoluminescence (TL) for structural, morphological and luminescent properties. Dy 3+ activated Sr 5 (PO 4) 3 F phosphor shows its characteristic PL emission at 481 nm and 574 nm due to 4 F 9/2 → 6 H 15/2 and 4 F 9/2 → 6 H 13/2 transitions, respectively. TL characteristics of Dy 3+ doped Sr 5 (PO 4) 3 F phosphors were taken after irradiation by 60 Co gamma exposure. Two separate TL peaks at 126 o C and 279 o C were observed in case of Dy 3+ doped phosphor. Sr 5 (PO 4) 3 F:Dy 3+ phosphor was irradiated within a wide range of exposure of 50 Gy to 7 kGy doses. Linearity was found up to 2 kGy and thereafter TL response saturates. Fading study was also carried out over the duration of six weeks for Sr 5 (PO 4) 3 F phosphor. Trapping parameters were calculated using Chen's peak shape method, initial rise method and various heating rate method. Glow curve is deconvoluted using computerized glow curve deconvolution program. TL sensitivity of Sr 5 (PO 4) 3 F:Dy 3+ phosphor is found to be less by a factor of 2.08 than commercially used CaSO 4 :Dy phosphor. In order to identify the defect centers formed upon ߛ-ray irradiation in Sr 5 (PO 4) 3 F:Dy 3+ phosphor, EPR measurements were carried out on un-irradiated and irradiated phosphors.
Trivalent terbium (Tb 3 þ) or samarium (Sm 3 þ) ions individually activated green and orange emitting Sr 2 Gd 8 Si 6 O 26 (SGSO) phosphors were synthesized by a citrate sol–gel method. The X-ray diffraction patterns of SGSO:Tb 3 þ and SGSO:Sm 3 þ phosphors exhibited the characteristic diffraction peaks of oxyapatite in a hexagonal lattice structure. The photoluminescence (PL) properties at ultraviolet (UV) or near-UV excitation wavelengths were measured for Tb 3 þ or Sm 3 þ ions doped SGSO phosphors as a function of its respective concentration. The PL spectra of SGSO:Tb 3 þ phosphors revealed the characteristic emission peaks of both Gd 3 þ and Tb 3 þ ions which are associated with 4f–4f transitions under 274 nm of excitation wavelength. When the concentration of Tb 3 þ ions increased over 0.05 mol (5 mol%), the emission intensities of 5 D 3 transitions decreased due to the well-known cross-relaxation process. However, based on the intensities of 5 D 4 transitions, the optimum concentration of Tb 3 þ ions was found to be 0.05 mol. Under 404 nm of excitation wavelength, the SGSO:Sm 3 þ phosphors exhibited the characteristic orange emission at 600 nm due to the 4 G 5/2-6 H 7/2 electronic transition. The optimum concentration of SGSO:Sm 3 þ phosphors was found to be 0.02 mol. The decay curves of the optimized SGSO: Tb 3 þ and SGSO:Sm 3 þ phosphors were well fitted to single exponential functions and their lifetimes were calculated. Furthermore, the optimized phosphor samples showed good thermal stability. Likewise, cathodoluminescence properties were also studied for the optimized samples as a function of filament current and accelerating voltage. The Commission International de I-Eclairage chromaticity coordinates were calculated for the SGSO:Tb 3 þ and SGSO:Sm 3 þ phosphors.
Sol–Gel Synthesis of Translucent and Persistent Luminescent SiO2@ SrAl2O4 Eu, Dy, B Materials
Materials
This publication offers an economically promising method of persistent luminescent silicate glass synthesis that does not involve high temperatures or ready-made (separately synthesized) PeL particles. In this study, we demonstrate the formation of SrAl2O4 doped with Eu, Dy, and B in a SiO2 glass structure using the one-pot low-temperature sol–gel synthesis method. By varying the synthesis conditions, we can use water-soluble precursors (e.g., nitrates) and a dilute aqueous solution of rare-earth (RE) nitrates as starting materials for SrAl2O4 synthesis, which can be formed during the sol–gel process at relatively low sintering temperatures (600 °C). As a result, translucent, persistently luminescent glass is obtained. The glass shows the typical Eu2+ luminescence and the characteristic afterglow. The afterglow duration is about 20 s. It is concluded that the slow drying procedure (2 weeks) is optimal for these samples to sufficiently get rid of the excess water (mainlyOH groups) an...