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1.
An Er3+‐doped phosphor of Gd2O3 (Gd2O3:Er3+) was prepared using a conventional solid‐state reaction method. The structure and particle size were determined from X‐ray powder diffraction measurements. The average particle size of the phosphor was in between 20 and 50 nm. The particle size and structure of the phosphor were further confirmed by transmission electron microscopy (TEM) analysis. Luminescence spectra were recorded under excitation wavelengths of 275, 380, 515 and 980 nm. The visible upconversion and downconversion luminescence spectra of the Gd2O3:Er3+ phosphor were investigated as a function of Er3+ ion concentration. The upconverted emission at 980 nm excitation shows enhanced red emission with respect to green emission as the dopant concentration increased. Similar results were observed for downconversion emission under 275 and 380 nm excitation wavelengths. The mechanisms responsible for populating the 4S3/2 and 4 F9/2 levels, for green and red emissions, respectively, are different for different excitations and for different concentrations of Er3+. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

2.
Tin oxide (SnO2) nanocrystalline powders doped with erbium ion (Er3+) in different molar ratios (0, 3, 5, and 7 mol%) were prepared using a solid-state reaction technique. These samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet-visible absorption, visible upconversion, and near-infrared luminescence techniques. XRD analysis revealed the tetragonal rutile structure of SnO2 and the average crystallite size was about 32 nm. From Tauc's plots, it was confirmed that the substitution of Er3+ ions into the SnO2 host lattice resulted in the narrowing its band gap. Optical absorption bands at 520 and 654 nm correspond to the 4f electron transitions of Er3+ further confirming visible light absorption. Infrared luminescence spectra showed a broad band centred at 1536 nm which is assigned to the 4I13/24I15/2 transition of Er3+. Visible upconverted emission spectra under 980 nm excitation exhibit a strong red luminescence with a main peak at 672 nm which is attributed to the 4F9/24I15/2 transition of Er3+. Power-dependent upconversion spectra confirmed that two photons participated in the upconversion mechanism. Enhancement in the intensities of both visible and infrared luminescence was observed when raising the concentration. The results pave the way for the potential applications of these nanocrystalline powders in energy harvesting applications such as infrared light upconverting layer in solar cells, light emitting diodes, infrared broadband sources and amplifiers, and biological labelling.  相似文献   

3.
We report the synthesis and structural characterization of Er3+,Yb3+‐doped Gd2O3 phosphor. The sample was prepared using the conventional solid‐state reaction method, which is the most suitable method for large‐scale production. The prepared phosphor sample was characterized using X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), thermoluminescence (TL), photoluminescence (PL) and CIE techniques. For PL studies, the excitation and emission spectra of Gd2O3 phosphor doped with Er3+ and Yb3+ were recorded. The excitation spectrum was recorded at a wavelength of 551 nm and showed an intense peak at 276 nm. The emission spectrum was recorded at 276 nm excitation and showed peaks in all blue, green and red regions, which indicate that the prepared phosphor may act as a single host for white light‐emitting diode (WLED) applications, as verified by International de I'Eclairage (CIE) techniques. From the XRD data, the calculated average crystallite size of Er3+ and Yb3+‐doped Gd2O3 phosphor is ~ 38 nm. A TL study was carried out for the phosphor using UV irradiation. The TL glow curve was recorded for UV, beta and gamma irradiations, and the kinetic parameters were also calculated. In addition, the trap parameters of the prepared phosphor were also studied using computerized glow curve deconvolution (CGCD). Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

4.
This paper reports the synthesis and characterization of Er3+‐doped CeO2 phosphor with variable concentrations of erbium. The sample was synthesized using a solid‐state reaction method, which is useful for the large‐scale production of phosphors and is also eco‐friendly. The prepared sample was characterized using an X‐ray diffraction (XRD) technique. The XRD pattern confirmed that sample has the pure cubic fluorite crystal structure of CeO2. The crystallite size of the prepared phosphor was determined by Scherer's formula and the crystallite size giving an intense XRD peak is 40.06 nm. The surface morphology of the phosphor was determined by field emission gun scanning electron microscopy (FEGSEM). From the FEGSEM image, good surface morphology with some agglomerates was found. The functional group in the prepared sample was analysed by Fourier transform infrared (FTIR) spectroscopy. All samples prepared with variable concentrations of Er3+ (0.1–2 mol%) were studied by photoluminescence analysis and it was found that the excitation spectra of the prepared phosphor shows broad excitation centred at 251 nm. Emission spectra at different concentrations of Er3+ show strong peaks at 413 and 470 nm and a weaker peak at 594 nm. The dominant peaks at 413 and 470 nm are caused by the allowed electronic transition 4S3/24I15/2 and the weaker transition at 594 nm is due to the transition 4 F9/24I15/2. Spectrophotometric determinations of peaks were evaluated using the Commission Internationale de I'Eclairage (CIE) technique. The emission spectra were also observed using an infrared (IR) laser 980 nm source, and three distinct peaks were found in the IR region at 848, 870 and 980 nm. The prepared phosphor has utility for application in display devices. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

5.
In the yttrium aluminium system, the YAlO3 phosphor is a prominent host because of the yttrium aluminium ratio (1:1). Phosphor was synthesized by the solid‐state reaction method at variable concentrations of erbium (0.1–2.5 mol%). This method is suitable for large‐scale production and is a less time‐consuming method when compared with the soft synthesis method. The prepared sample was characterized by X‐ray diffraction technique and the crystallite size was calculated by Scherer's formula. Vibrational and bending analysis of prepared phosphor for optimized concentration of erbium ion is described based on the Fourier transform infrared spectroscopic technique. The photoluminescence (PL) emission spectra of prepared phosphor for variable concentrations of erbium ion were recorded and the excitation spectrum was found to be at 291 nm with three shoulder peaks at 305, 270 and 242 nm. For 291 nm excitation, the emission spectrum was found at 546 nm and 552 nm. PL intensity increased with increasing concentrations of erbium and after 2 mol% emission intensity decreased due to concentration quenching. Spectrophotometric determination of YAlO3:Er3+ is described by CIE co‐ordinates and shows an intense emission in the green region such that the prepared phosphor can act as a single host for green light emission. Thermoluminescence glow curve analysis of the YAlO3:Er3+ phosphor was recorded for different ultraviolet (UV) light exposures and gamma exposure. Different gamma doses 0.5–2 kGy show a linear response. Kinetic parameters were calculated by the peak shape method. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

6.
LaOBr:Yb3+/Er3+ nanofibers were synthesized for the first time by calcinating electrospun PVP/[La(NO3)3 + Er(NO3)3 + Yb(NO3)3 + NH4Br] composites. The morphology and properties of the final products were investigated in detail using scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS), X‐ray diffractometry (XRD) and fluorescence spectroscopy. The results indicate that LaOBr:Yb3+/Er3+ nanofibers are tetragonal in structure with a space group of P4/nmm. The diameter of LaOBr:Yb3+/Er3+ nanofibers is ~ 147 nm. Under the excitation of a 980‐nm diode laser, LaOBr:Yb3+/Er3+ nanofibers emit strong green and red up‐conversion emission centering at 519, 541 and 667 nm, ascribed to the 2H11/2, 4S3/24I15/2 and 4 F9/24I15/2 energy‐level transitions of Er3+ ions, respectively. The up‐conversion luminescent mechanism of LaOBr:Yb3+/Er3+ nanofibers is advanced. Moreover, near‐infrared emission of LaOBr:Yb3+/Er3+ nanofibers is obtained under the excitation of a 532‐nm laser. The formation mechanism of LaOBr:Yb3+/Er3+ nanofibers is proposed. LaOBr:Yb3+/Er3+ nanofibers could be important up‐conversion luminescent materials. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

7.
In this study, Bi3+ incorporation in NaYbF4:Er lattice and its influence on upconversion luminescence properties have been investigated in detail using techniques such as temperature‐dependent luminescence, Fourier transform infrared spectroscopy and X‐ray diffraction (XRD). The study was carried out to develop phosphors with improved upconversion luminescence. From photoluminescence and lifetime measurements it is inferred that luminescence intensity from NaYbF4:Er increases with Bi3+ addition. The sample containing 50 at.% Bi3+ ions exhibited optimum upconversion luminescence. Increased distance between Yb3+–Yb3+ and Er3+–Er3+ due to Bi3+ incorporation into the lattice and associated decrease in the extent of dipolar interaction/self‐quenching are responsible for increase in lifetime values and luminescence intensities from Er3+ ions. Incorporation of Bi3+ into NaYbF4:Er lattice reduced self‐quenching among Yb3+–Yb3+ions and this facilitated energy transfer from Yb3+ to Er3+. This situation also explains decrease in the extent of temperature‐assisted quenching of emission from thermally coupled 2H11/2 and 4S3/2 levels of Er3+. Based on Rietveld refinement of XRD patterns it was confirmed that a maximum of 10 at.% of Bi3+added was incorporated into the NaYbF4:Er lattice and the remaining complex co‐exists as a BiOF phase. These results are of significant interest in the area of development of phosphors based on Yb3+–Er3+ upconversion luminescence.  相似文献   

8.
Erbium‐doped nano‐sized Gd2O3 phosphor was prepared by a solution combustion method in the presence of urea as a fuel. The phosphor was characterized by X‐ray diffractometry (XRD), Fourier transform infra‐red spectroscopy, energy dispersive X‐ray analysis (EDX) and transmission electron microscopy (TEM). The results of the XRD shows that the phosphor has a monoclinic phase, which was further confirmed by the TEM results. Particle size was calculated by the Debye–Scherrer formula. The erbium‐doped Gd2O3 nanophosphor was revealed to have good down‐conversion (DC) properties and the intensity of phosphor could be modified by annealing. The effects of annealing at 900°C on the particle size and luminescence properties were studied and compared with freshly prepared Gd2O3:Er3+ nanoparticles. The average particle sizes were calculated as 8 and 20 nm for the freshly prepared samples and samples annealed at 900°C for 1 h, respectively. The results show that both freshly prepared and annealed Gd2O3:Er3+ have monoclinic structure. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

9.
K. N. Shinde  K. Park 《Luminescence》2013,28(5):793-796
A series of efficient Li3Al2(PO4)3:Eu2+ novel phosphors were synthesized by the facile combustion method. The effects of dopant on the luminescence behavior of Li3Al2(PO4)3 phosphor were also investigated. The phosphors were characterized by X‐ray diffraction, field emission scanning electron microscope and photoluminescence techniques. The result shows that all samples can be excited efficiently by near‐ultraviolet excitation under 310 nm. The emission was observed for Li3Al2(PO4)3:Eu2+ phosphor at 425 nm, which corresponded to the d → f transition. The concentration quenching of Eu2+ was observed in Li3Al2(PO4)3:Eu2+ when the Eu concentration was at 0.5 mol%. The prepared powders exhibited intense blue emission at the 425 nm owing to the Eu2+ ion by Hg‐free excitation at 310 nm (i.e., solid‐state lighting excitation). Consequently, the availability of such a phosphor will significantly help in the development of blue‐emitting solid‐state lighting applications. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

10.
An intense green photostimulated luminescence in BaAl2O4:Eu2+ phosphor was prepared. The thermoluminescence results indicate that there are at least three types of traps (T1, T2, T3) with different trap depths in BaAl2O4:Eu2+ phosphor according to the bands located at 327, 361 and 555 K, respectively, which are closely associated with the phosphor's long persistent luminescence and photostimulated luminescence properties. In addition, as a novel optical read‐out form, a photostimulated persistent luminescence signal can be repeatedly obtained in BaAl2O4:Eu2+ phosphor. This shows that re‐trapping of the electron released from a deep trap plays an important role in photostimulated persistent luminescence. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

11.
Many sulfides are toxic substances that easily harm the respiratory tract, therefore affecting respiratory function or damaging other organs of the body, leading to its failure. Therefore, there is a pressing need to develop methods for sensitive detection of sulfur ions (S2?). Based on luminescence resonance energy transfer (LRET) theory, we report the construction of a near‐infrared (NIR) excitation luminescence probe using NaGdF4:Yb3+,Er3+@NaYF4 upconversion nanoparticles (UCNPs) as the donor and dye‐670 as the receptor for detection of S2?. When UCNPs and dye‐670 molecules were combined using ligand exchange and electrostatic attraction, LRET occurred and UCNP luminescence was quenched. When S2? was added to the system, sulfide ions were able to destroy the double bond of the dye, inhibiting LRET and restoring UCNP luminescence. Under optimum condition, the linear range of S2? detection was 0.65–18.2 μM, and the detection limit was 34.2 nM. This method was applied for determination of S2? in water with satisfactory results.  相似文献   

12.
Incorporating the Gd3+ rare earth ion in the LiCaBO3 host lattice resulted in narrow‐band UV‐B emission peaking at 315 nm, with excitation at 274 nm. The LiCaBO3:Gd3+ phosphor was synthesized via the solid‐state diffusion method. The structural, morphological and luminescence properties of this phosphor were characterized by X‐ray diffraction (XRD) analysis, scanning electron microscopy (SEM) and photoluminescence (PL) spectroscopy. Electron paramagnetic resonance (EPR) characterization of the as‐prepared phosphors is also reported here. XRD studies confirmed the crystal formation and phase purity of the prepared phosphors. A series of different dopant concentrations was synthesized and the concentration‐quenching effect was studied. Critical energy transfer distance between activator ions was determined and the mechanism governing the concentration quenching is also reported in this paper. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

13.
CaSnO3:Bi3+ blue‐emitting phosphor was synthesized using a high‐temperature solid‐state reaction method in air. The crystal structures and luminescence properties were investigated. A broad emission band peaking at ~448 nm upon excitation at 262 and 308 nm was observed in the range 330–680 nm at room temperature due to 3P1 → 1S0 transition of the Bi3+ ion. The chromaticity coordinate was (0.1786, 0.1665). The optimal Bi3+ ion concentration was ~0.6 mol% in CaSnO3:Bi3+ phosphor. The emission spectrum of CaSnO3:Bi3+ phosphor showed a blue‐shift with increasing temperature from 50 to 300 K due to the influence of temperature on the electron transition of the Bi3+ ion. The emission intensity of CaSnO3:Bi3+ phosphor may be increased ~1.45 times by co‐doping Li+ ions as a charge compensator and fluxing agent. The luminescence mechanism is explained by a configurational coordinate diagram of Bi3+ ion in CaSnO3:Bi3+ phosphor.  相似文献   

14.
We used the synthesized dinaphthylmethane (Hdnm) ligand whose absorption extends to the visible‐light wavelength, to prepare a family of ternary lanthanide complexes, named as [Ln(dnm)3phen] (Ln = Sm, Nd, Yb, Er, Tm, Pr). The properties of these complexes were investigated by Fourier transform infrared (FT‐IR) spectroscopy, diffuse reflectance (DR) spectroscopy, thermogravimetric analyses, and excitation and emission spectroscopy. Generally, excitation with visible light is much more advantageous than UV excitation. Importantly, upon excitation with visible light (401–460 nm), the complexes show characteristic visible (Sm3+) as well as near‐infrared (Sm3+, Nd3+, Yb3+, Er3+, Tm3+, Pr3+) luminescence of the corresponding lanthanide ions, attributed to the energy transfer from the ligands to the lanthanide ions, an antenna effect. Now, using these near‐infrared luminescent lanthanide complexes, the luminescent spectral region from 800 to 1650 nm, can be covered completely, which is of particular interest for biomedical imaging applications, laser systems, and optical amplification applications. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

15.
Eu3+‐activated Y(P,V)O4 phosphors were prepared by the EDTA sol‐gel method, and the corresponding morphologies and luminescent properties were investigated. The sample particles were relatively spheroid with size of 2–3 µm and had a smooth surface. The excitation spectra for Y(P,V)O4:Eu3+ consisted of three strong excitation bands in the 200–350 nm range, which were attributed to a Eu3+‐ O2? charge‐transfer band and 1A1?1 T1/1 T2 transitions in VO43?. The as‐synthesized phosphors exhibited a highly efficient red luminescence at 613 nm due to the Eu3+ 5D0?7 F2 electric dipole transition. With the increase in the V5+/P5+ ratio, the luminescence intensity of the red phosphor under UV excitation was greatly improved due to enhanced VO43? → Eu3+ energy transfer. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

16.
In this work, we studied the luminescence properties of Tb3+‐doped MgPbAl10O17 green phosphor. To understand the excitation mechanism and corresponding emission of the prepared phosphor, its structural, morphological and photoluminescence properties were investigated. In general, for green emission, Tb3 is used as an activator and the obtained excitation and emission spectra indicated that this phosphor can be effectively excited by a wavelength of 380 nm, and exhibits bright green emission centered at 545 nm corresponding to the f → f transition of trivalent terbium ions. The chromaticity coordinates were (Cx = 0.263, Cy = 0.723). The impact of Tb3+ concentration on the relative emission intensity was investigated, and the best doping concentration was found to be 2 mol%. This study suggests that Tb3+‐doped MgPbAl10O17 phosphor is a strong candidate for a green component in phosphor‐converted white light‐emitting diodes. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

17.
KBaPO4 luminescent powdered phosphors doped with rare earth elements (RE = Sm3+,Eu3+,Dy3+) were successfully synthesized using a wet chemical method to identify the most suitable phosphor for solid‐state lighting based on the measurement of their emission spectra at excitation wavelengths. The X‐ray diffraction pattern of the as‐prepared KBaPO4 was well matched with its standard JCPDS file no. 330996, indicating the formation of the desired compound. Scanning electron microscopy images revealed irregular morphology, the material crystallized particles aggregated and were non‐uniform with particle sizes ranging from 1 to 100 μm. Photoluminescence excitation and emission spectra clearly indicated that the phosphor containing the Sm3+‐activated KBaPO4 phosphors could be efficiently excited at 403 nm and exhibited an emission mainly including two wavelength peaks at 559 nm and 597 nm. The phosphor containing the Eu3+‐activated KBaPO4 phosphors could be efficiently excited at 396 nm and exhibited a bright red emission mainly including two wavelength peaks at 594 nm and 617 nm. The phosphor containing the Dy3+‐activated KBaPO4 phosphors could be efficiently excited at 349 nm and exhibited wavelength peaks at 474 nm and 570 nm.  相似文献   

18.
Optical materials composed of Ba9–3(m+n)/2ErmYbnY2Si6O24 (m = 0.005–0.2, n = 0–0.3) were prepared using a solid‐state reaction. The X‐ray diffraction patterns of the obtained phosphors were examined to index the peak positions. The photoluminescence (PL) excitation and emission spectra of the Er3+‐activated phosphors and the critical emission quenching as a function of Er3+ content in the Ba9–3m/2ErmY2Si6O24 structure were monitored. The spectral conversion properties of Er3+ and Er3+–Yb3+ ions doped in Ba9Y2Si6O24 phosphors were elucidated under diode‐laser irradiation at 980 nm. Up‐conversion emission spectra and the dependence of the emission intensity on pump power for the Ba8.55Er0.1Yb0.2Y2Si6O24 phosphor were investigated. The desired up‐conversion of the emitted light, which passed through the green, yellow, orange and red regions of the spectrum, was achieved through the use of appropriate Er3+ and/or Yb3+ concentrations in the host structure and 980 nm excitation light. The up‐conversion mechanism in the phosphors is described by an energy‐level schematic. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

19.
A series of Eu3+‐, Ce3+‐, Dy3+‐ and Tb3+‐doped (Y,Gd)BO3 phosphors was synthesized by a solid‐state diffusion method. X‐Ray diffraction confirmed their hexagonal structure and the scanning electron microscopy results showed crystalline particles. The excitation spectra revealed that (Y,Gd)BO3 phosphors doped with Eu3+, Ce3+ , Dy3+ and Tb3+ are effectively excited with near UV‐light of 395 nm/blue light, 364, 351 and 314 nm, respectively. Photoluminescence spectra of Eu3+‐, Ce3+‐ and Tb3+/Dy3+‐doped phosphor showed intense emission of reddish orange, blue and white light, respectively. The phosphor Y0.60Gd0.38BO3:Ce0.02 showed CIE 1931 color coordinates of (0.158, 0.031) and better color purity compared with commercially available blue BAM:Eu2+ phosphor. The phosphor (Y,Gd)BO3 doped with Eu3+, Dy3+ and Tb3+ showed CIE 1931 color coordinates of (0.667, 0.332), (0.251, 0.299) and (0.333, 0.391) respectively. Significant photoluminescence characteristics of the prepared phosphors indicate that they might serve as potential candidates for blue chip and near‐UV white light‐emitting diode applications. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

20.
Eu2+‐activated SrMg2Al16O27 novel phosphor was synthesized by a combustion method (550°C furnace). The prepared phosphor was first characterized by X‐ray diffraction (XRD) for confirmation of phase purity. SEM analysis showed the morphology of the phosphor. The photoluminescence characteristics showed broad‐band excitation at 324 nm, which was monitored at 465 nm emission wavelength. The SrMg2Al16O27:Eu2+ phosphor shows broad blue emission centred at 465 nm, emitting a blue light corresponding to 4f65d1 → 4f7 transition. Here we report the photoluminescence characteristics of the prepared phosphor and compare it with commercial BAM:Eu2+ phosphor. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

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