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1.
T. Kalpana Y. Gandhi V. Sudarsan M. Piasecki V. Ravi Kumar N. Veeraiah 《Luminescence》2016,31(7):1358-1363
BaO‐B2O3‐P2O5 glasses doped with a fixed concentration of Tb3+ ions and varying concentrations of Al2O3 were synthesized, and the influence of the Al3+ ion concentration on the luminescence efficiency of the green emission of Tb3+ ions was investigated. The optical absorption, excitation, luminescence spectra and fluorescence decay curves of these glasses were recorded at ambient temperature. The emission spectra of terbium ions when excited at 393 nm exhibited two main groups of bands, corresponding to 5D3 → 7Fj (blue region) and 5D4 → 7Fj (green region). From these spectra, the radiative parameters, viz., spontaneous emission probability A, total emission probability AT, radiative lifetime τ and fluorescent branching ratio β, of different transitions originating from the 5D4 level of Tb3+ ions were evaluated based on the Judd‐Ofelt theory. A clear increase in the quantum efficiency and luminescence of the green emission of Tb3+ ions corresponding to 5D4 → 7F5 transition is observed with increases in the concentration of Al2O3 up to 3.0 mol%. The improvement in emission is attributed to the de‐clustering of terbium ions by Al3+ ions and also to the possible admixing of wave functions of opposite parities. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
2.
This paper focuses on an optical study of a Tb3+/Bi3+‐doped and Sm3+/La3+‐ doped Ca2Al2SiO7 phosphor synthesized using combustion methods. Here, Ca2Al2SiO7:Sm3+ showed a red emission band under visible light excitation but, when it co‐doped with La3+ ions, the emission intensity was further enhanced. Ca2Al2SiO7:Tb3+ shows the characteristic green emission band under near‐ultraviolet light excitation wavelengths, co‐doping with Bi3+ ions produced enhanced photoluminescence intensity with better colour tunable properties. The phosphor exhibited better phase purity and crystallinity, confirmed by X‐ray diffraction. Binding energies of Ca(2p), Al(2p), Si(2p), O(1s) were studied using X‐ray photoelectron spectroscopy. The reported phosphor may be a promising visible light excited red phosphor for light‐emitting diodes and energy conversion devices. 相似文献
3.
Structural and luminescence properties of Sm3+‐doped bismuth phosphate glass for orange‐red photonic applications
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In the present study, the effect of bismuth oxide (Bi2O3) content on the structural and optical properties of 0.5Sm3+‐doped phosphate glass and the effect of concentration on structural and optical properties of Sm3+‐doped bismuth phosphate (BiP) glass were studied. Structural characterization was accomplished using X‐ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), Fourier transform infrared (FTIR) spectroscopy and 31P nuclear magnetic resonance (NMR) spectroscopy. Optical properties were studied using absorption, photoluminescence and decay measurements. Using optical absorption spectra, Judd–Ofelt parameters were derived to determine the local structure and bonding in the vicinity of Sm3+ ions. The emission spectra of Sm3+‐doped BiP glass showed two intense emission bands, 4G5/2→6H7/2 (orange) and 4G5/2→6H9/2 (red) for which the stimulated emission cross‐sections (σe) and branching ratios (β) were found to be higher. The quantum efficiencies were also calculated from decay measurements recorded for the 4G5/2 level of Sm3+ ions. The suitable combination of Bi2O3 (10 mol%) and Sm3+ (0.5 mol%) ions in these glasses acted as an efficient lasing material and might be suitable for the development of visible orange‐red photonic materials. 相似文献
4.
Emission analysis of Tb3+‐and Sm3+‐ion‐doped (Li2O/Na2O/K2O) and (Li2O + Na2O/Li2O + K2O/K2O + Na2O)‐modified borosilicate glasses
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B. Naveen Kumar Reddy S. Sailaja K. Thyagarajan Young Dahl Jho B. Sudhakar Reddy 《Luminescence》2018,33(3):486-494
Four series of borosilicate glasses modified by alkali oxides and doped with Tb3+ and Sm3+ ions were prepared using the conventional melt quenching technique, with the chemical composition 74.5B2O3 + 10SiO2 + 5MgO + R + 0.5(Tb2O3/Sm2O3) [where R = 10(Li2O /Na2O/K2O) for series A and C, and R = 5(Li2O + Na2O/Li2O + K2O/K2O + Na2O) for series B and D]. The X‐ray diffraction (XRD) patterns of all the prepared glasses indicate their amorphous nature. The spectroscopic properties of the prepared glasses were studied by optical absorption analysis, photoluminescence excitation (PLE) and photoluminescence (PL) analysis. A green emission corresponding to the 5D4 → 7F5 (543 nm) transition of the Tb3+ ions was registered under excitation at 379 nm for series A and B glasses. The emission spectra of the Sm3+ ions with the series C and D glasses showed strong reddish‐orange emission at 600 nm (4G5/2 →6H7/2) with an excitation wavelength λexci = 404 nm (6H5/2→4F7/2). Furthermore, the change in the luminescence intensity with the addition of an alkali oxide and combinations of these alkali oxides to borosilicate glasses doped with Tb3+ and Sm3+ ions was studied to optimize the potential alkali‐oxide‐modified borosilicate glass. 相似文献
5.
Enhanced luminescence and white light emission from Eu3+‐co‐doped K3Ca2(SO4)3Cl:Dy3+ phosphor with near visible ultraviolet excitation for white LEDs
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The luminescent properties of europium (Eu)‐ and dysprosium (Dy)‐co‐doped K3Ca2(SO4)3Cl halosulfate phosphors were analyzed. This paper reports the photoluminescence (PL) properties of K3Ca2(SO4)3Cl microphosphor doped with Eu and Dy and synthesized using a cost‐effective wet chemical method. The phosphors were characterized by X‐ray diffraction and scanning electron microscopy. The CIE coordinates were calculated to display the color of the phosphor. PL emission of the prepared samples show peaks at 484 nm (blue), 575 nm (yellow), 594 nm (orange) and 617 nm (red). The emission color of the Eu,Dy‐co‐doped K3Ca2(SO4)3Cl halophosphor depends on the doping concentration and excitation wavelength. The addition of Eu in K3Ca2(SO4)3Cl:Dy greatly enhances the intensity of the blue and yellow peaks, which corresponds to the 4 F9/2 → 6H15/2 and 4 F9/2 → 6H13/2 transitions of Dy3+ ions (under 351 nm excitation). The Eu3+/Dy3+ co‐doping also produces white light emission for 1 mol% of Eu3+, 1 mol% of Dy3+ in the K3Ca2(SO4)3Cl lattice under 396 nm excitation, for which the calculated chromaticity coordinates are (0.35, 0.31). Thus, K3Ca2(SO4)3Cl co‐doped with Eu/Dy is a suitable candidate for NUV based white light‐emitting phosphors technology. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
6.
Synthesis and photoluminescence characteristics of Sm3+‐doped Bi4Si3O12 red‐emitting phosphor
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A series of novel red‐emitting Sm3+‐doped bismuth silicate phosphors, Bi4Si3O12:xSm3+ (0.01 ≤ x ≤ 0.06), were prepared via the sol–gel route. The phase of the synthesized samples calcinated at 800 °C is isostructural with Bi4Si3O12 according to X‐ray diffraction results. Under excitation with 405 nm light, some typical peaks of Sm3+ ions centered at 566, 609, 655 and 715 nm are found in the emission spectra of the Sm3+‐doped Bi4Si3O12 phosphors. The strongest peak located at 609 nm is due to 4G5/2–6H7/2 transition of Sm3+. The luminescence intensity reaches its maximum value when the Sm3+ ion content is 4 mol%. The results suggest that Bi4Si3O12:Sm3+ may be a potential red phosphor for white light‐emitting diodes. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
7.
Yu‐Guo Yang Xu‐Ping Wang Bing Liu Yuan‐Yuan Zhang Xian‐Shun Lv Jing Li Lei Wei Hua‐Jian Yu Yanyan Hu Hua‐Di Zhang 《Luminescence》2020,35(4):580-585
Dy3+‐doped Y3Al5O12 phosphors were prepared at a relatively low temperature using molten salt synthesis. The phase of the prepared Dy3+‐doped Y3Al5O12 phosphors was confirmed using X‐ray powder diffraction. Results indicated that Dy3+ doping did not change the Y3Al5O12 phase. Following excitation at 352 nm, emission spectra of the Dy3+‐doped Y3Al5O12 phosphors consisted of blue, yellow, and red emission bands. The influence of Dy3+ concentration and excitation wavelength on emission was investigated. The ratio of yellow light to blue light varied with change in Dy3+ doping concentration, due to changes in the structure around Dy3+. Emission intensities also changed when the excitation wavelength was changed. This variation is luminescence generated a system for tunable white light for Dy3+‐doped Y3Al5O12 phosphors. 相似文献
8.
Sapizah Rahim Muhammad Taqiyuddin Mawardi Ayob Muhammad Hassyakirin Hasim Irman Abdul Rahman Shahidan Radiman 《Luminescence》2019,34(7):699-706
Gd2O2S:Eu3+ nanophosphors have been successfully synthesized using microwave irradiation and γ‐irradiation methods with polyvinyl pyrrolidone as a stabilizer. The physical and luminescence spectra were compared. The morphologies of both Gd2O2S:Eu3+ nanophosphors were in the hexagonal phase and mainly consisted of spherical nanostructures with diameters of ~90 nm and ~50 nm for both microwave irradiation and γ‐irradiation methods. Upon 325 nm of ultraviolet (UV) light excitation, strong red emissions (626 nm) were observed for both methods; these emissions corresponded to the 5D0→7F2 transition of Eu3+ ions. However, Gd2O2S:Eu3+ nanophosphors following microwave treatment showed better luminescence intensity than Gd2O2S:Eu3+ nanophosphors treated with γ‐irradiation. This difference was attributed to the crystallinity phase and surface quenching effects of Gd2O2S:Eu3+ nanophosphors. The reaction mechanisms of Gd2O2S:Eu3+ nanophosphors in both methods are discussed in detail. 相似文献
9.
An efficient orange–red‐emitting LiNa3P2O7:Sm3+ pyrophosphate: Structural and optical analysis for solid‐state lighting
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G.R. Dillip K. Munirathnam B. Deva Prasad Raju N. John Sushma S.W. Joo 《Luminescence》2017,32(5):772-778
A trivalent rare‐earth ion (Sm3+)‐doped LiNa3P2O7 (LNPO) phosphor was synthesized using a conventional high‐temperature solid‐state reaction route. A predominant orthorhombic phase of LNPO was observed in all X‐ray diffraction patterns. The surface states of the LNPO:Sm phosphor were confirmed by X‐ray photoelectron spectroscopy. Under 401 nm excitation, the Sm‐doped LNPO phosphors showed sharp emission peaks at 563, 600 and 647 nm that are related to the f–f transition of Sm3+ ions. The optimum concentration of Sm3+ (9 mol%) produced Commission Internationale de l'Eclairage chromaticity coordinates, color rendering index and correlated color temperature of (0.564, 0.434), 42 and 1843 K, respectively. 相似文献
10.
Concentration‐dependent studies of Nd3+‐doped zinc phosphate glasses for NIR photoluminescence at 1.05 μm
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Nd3+‐doped lead‐free zinc phosphate glasses with the chemical compositions (60‐x) NH4H2PO4 + 20ZnO + 10BaF2 + 10NaF + xNd2O3 (where x = 0.5, 1.0, 1.5, 2.0 and 2.5 mol%) were prepared using a melt quenching technique. Vibrational bands were assigned and clearly elucidated by Raman spectral profiles for all the glass samples. Judd–Ofelt (J–O) intensity parameters (Ωλ: λ = 2, 4, 6) were obtained from the spectral intensities of different absorption bands of Nd3+ ions. Radiative properties such as radiative transition probabilities (AR), radiative lifetimes (τR) and branching ratios (βR) for different excited states were calculated using J–O parameters. The near infrared (NIR) photoluminescence spectra exhibited three emission bands (4F3/2 level to 4I13/2, 4I11/2 and 4I9/2 states) for all the concentrations of Nd3+ ions. Various luminescence properties were studied by varying the Nd3+ concentration for the three spectral profiles. Fluorescence decay curves of the 4F3/2 level were recorded. The energy transfer mechanism that leads to quenching of the 4F3/2 state lifetimes was discussed at higher concentration of Nd3+ ions. These glasses are suggested as suitable hosts to produce efficient lasing action in NIR region at 1.05 μm. 相似文献
11.
Concentration dependence of luminescence efficiency of Dy3+ ions in strontium zinc phosphate glasses mixed with Pb3O4
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In this work we synthesized SrO–ZnO–P2O5 glasses mixed with Pb3O4 (heavy metal oxide) and doped with different amounts of Dy2O3 (0.1 to 1.0 mol%). Subsequently their emission and decay characteristics were investigated as a function of Dy2O3 concentration. The emission spectra exhibited three principal emission bands in the visible region corresponding to 4F9/2 → 6H15/2 (482 nm), 6H13/2 (574 nm) and 6H11/2 (663 nm) transitions. With increase in the concentration of Dy2O3 (upto 0.8 mol%) a considerable increase in the intensity of these bands was observed and, for further increase, quenching of photoluminescence (PL) output was observed. Using emission spectra, various radiative parameters were evaluated and all these parameters were found to increase with increase in Dy2O3 concentration. The Y/B integral emission intensity ratio of Dy3+ ions evaluated from these spectra exhibited a decreasing trend with increase in the Dy2O3 concentration up to 0.8 mol%. Quenching of luminescence observed in the case of the glasses doped with 1.0 mol% is attributed to clustering of Dy3+ ions. The quantitative analysis of these results together with infra‐red (IR) spectral studies indicated that 0.8 mol% is the optimum concentration of Dy3+ ions needed to achieve maximum luminescence efficiency. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
12.
A series of Ca6AlP5O20 doped with rare earths (Eu and Ce) and co‐doped (Eu, Ce and Eu,Mn) were prepared by combustion synthesis. Under Hg‐free excitation, Ca6AlP5O20:Eu exhibited Eu2+ (486 nm) emission in the blue region of the spectrum and under near Hg excitation (245 nm), Ca6AlP5O20:Ce phosphor exhibited Ce3+ emission (357 nm) in the UV range. Photoluminescence (PL) peak intensity increased in Ca6AlP5O20:Eu,Ce and Ca6AlP5O20:Eu, Mn phosphors due to co‐activators of Ce3+ and Mn2+ ions. As a result, these ions played an important role in PL emission in the present matrix. Ca6AlP5O20:Eu, Ce and Ca6AlP5O20:Eu, Mn phosphors provided energy transfer mechanisms via Ce3+ → Eu2+ and Eu2+ → Mn2+, respectively. Eu ions acted as activators and Ce ions acted as sensitizers. Ce emission energy was well matched with Eu excitation energy in the case of Ca6AlP5O20:Eu, Ce and Eu ions acted as activators and Mn ions acted as sensitizers in Ca6AlP5O20:Eu, Mn. This study included synthesis of new and efficient phosphate phosphors. The impact of doping and co‐doping on photoluminescence properties and energy transfer mechanisms were investigated and we propose a feasible interpretation. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
13.
An energy transfer process from Ce3+ to Tb3+ ions was successfully achieved in a Li2SO4–Al2(SO4)3 mixed‐sulphate system. A wet‐chemical synthesis was employed to prepare the Li2SO4–Al2(SO4)3 system by doping Ce3+ and Tb3+ ions individually as well as collectively. The phases were identified using X‐ray diffraction studies. The as‐prepared samples were characterized by FT‐IR and photoluminescence measurements. Green‐light emission was exhibited by Ce3+, Tb3+ co‐doped Li2SO4–Al2(SO4)3 system, thus, indicating its potential as a material for display devices or in the lamp industry. 相似文献
14.
Volatile Eu complexes, namely Eu(TTA)3Phen, Eu(x)Y(1‐x)(TTA)3 Phen; Eu(x)Tb(1‐x)(TTA)3Phen; Eu, europium; Y, yttrium; Tb, Terbium; TTA, thenoyltrifluoroacetone; and Phen, 1,10 phenanthroline were synthesized by maintaining stichiometric ratio. Various characterization techniques such as X‐ray diffraction (XRD), photoluminescence (PL) and thermo gravimetric analysis/differential thermal analysis (TGA/DTA) were carried out for the synthesized complexes. Diffractograms of all the synthesized complexes showed well‐resolved peaks, which revealed that pure and doped organic Eu3+ complexes were crystalline in nature. Of all the synthesized complexes, Eu0.5 Tb0.5(TTA)3Phen showed maximum peak intensity, while the angle of maximum peak intensity for all complexes was almost the same with slightly different d‐values. A prominent sharp red emission line was observed at 611 nm when excited with light at 370 nm. It was observed that the intensity of red emissions increased for doped europium complexes Eu(x)Y(1‐x)(TTA)3Phen and Eu(x)Tb(1‐x)(TTA)3 Phen, when compared with Eu complexes. Emission intensity increased in the following order: Eu(TTA)3Phen > Eu0.5 Tb0.5(TTA)3Phen > Eu0.4 Tb0.6(TTA)3Phen > Eu0.5Y0.5(TTA)3Phen > Eu0.4Y0.6(TTA)3Phen, proving their potential application in organic light‐emitting diodes (OLEDs). TGA showed that Eu complexes doped in Y3+ and Tb3+ have better thermal stability than pure Eu complex. DTA analysis showed that the melting temperature of Eu(TTA)3 Phen was lower than doped Eu complexes. These measurements infer that all complexes were highly stable and could be used as emissive materials for the fabrication of OLEDs. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
15.
Photoluminescence and thermoluminescence properties of Eu2+ doped and Eu2+,Dy3+ co‐doped Ba2MgSi2O7 phosphors
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In this work, we report the preparation, characterization, comparison and luminescence mechanisms of Eu2+‐doped and Eu2+,Dy3+‐co‐doped Ba2MgSi2O7 (BMSO) phosphors. Prepared phosphors were synthesized via a high temperature solid‐state reaction method. All prepared phosphors appeared white. The phase structure, particle size, and elemental analysis were analyzed using X‐ray diffraction (XRD), transmission electron microscopy (TEM) and energy‐dispersive X‐ray (EDX) analysis. The luminescence properties of the phosphors were investigated by thermoluminescence (TL) and photoluminescence (PL). The PL excitation and emission spectra of Ba2MgSi2O7:Eu2+ showed the peak to be around 381 nm and 490 nm respectively. The PL excitation spectrum of Ba2MgSi2O7:Eu2+Dy3+ showed the peak to be around 341 nm and 388 nm, and the emission spectrum had a broad band around 488 nm. These emissions originated from the 4f6 5d1 to 4f7 transition of Eu2+. TL analysis revealed that the maximum TL intensity was found at 5 mol% of Eu2+ doping in Ba2MgSi2O7 phosphors after 15 min of ultraviolet (UV) light exposure. TL intensity was increased when Dy3+ ions were co‐doped in Ba2MgSi2O7:Eu2+ and maximum TL intensity was observed for 2 mol% of Dy3+. TL emission spectra of Ba1.95MgSi2O7:0.05Eu2+ and Ba1.93MgSi2O7:0.05Eu2+,0.02Dy3+ phosphors were found at 500 nm. TL intensity increased with UV exposure time up to 15 min, then decreased for the higher UV radiation dose for both Eu doping and Eu,Dy co‐doping. The trap depths were calculated to be 0.54 eV for Ba1.95MgSi2O7:0.05Eu2+ and 0.54 eV and 0.75 eV for Ba1.93MgSi2O7:0.05Eu2+,0.02Dy3+ phosphors. It was observed that co‐doping with small amounts of Dy3+ enhanced the thermoluminescence properties of Ba2MgSi2O7 phosphor. Copyright © 2016 John Wiley & Sons, Ltd. [Correction added on 5 April 2016, after first online publication: The following parts of the abstract have been edited for consistency. '4f65d1' has been corrected to '4f6 5d1', '4f7' has been corrected to '4f7', 'Ba1.95' has been corrected to 'Ba1.95' and 'Ba1.93' has been corrected to 'Ba1.93' respectively.] 相似文献
16.
Frequency up‐conversion (UC) emission from the Nd3+‐Yb3+/Nd3+‐Yb3+‐Li+ co‐doped gadolinium oxide (Gd2O3) phosphors prepared by the solution combustion technique in the visible range have been studied by using 980 nm near infrared (NIR) laser diode excitation. The crystalline structure and formation of the cubic phase has been confirmed with the help of X‐ray diffraction (XRD) studies. XRD peak shifts have been found towards the lower diffraction angle side in the case of the Nd3+‐Yb3+‐Li+ co‐doped phosphors. Surface morphology and particle size information have been observed by using field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) analysis. Down‐conversion emission study under 351 nm excitation in the visible region for the Nd3+‐Yb3+/Nd3+‐Yb3+‐Li+ co‐doped phosphors has been performed. The UC emission bands lying in the green and red region arising from the Nd3+ ions have been enhanced by ~260 times, ~113 times due to incorporation of Li+ ions in the Nd3+‐Yb3+ co‐doped phosphors. Photometric characterization has been done for the Nd3+‐Yb3+/Nd3+‐Yb3+‐Li+ co‐doped phosphors. The present study suggests the capability of the synthesized phosphors in near‐infrared (NIR) to visible upconverter and luminescent device applications. 相似文献
17.
Thermoluminescence and photoluminescence studies on γ‐ray‐irradiated Ce3+,Tb3+‐doped potassium chloride single crystals
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Single crystals of KCl doped with Ce3+,Tb3+ were grown using the Bridgeman–Stockbarger technique. Thermoluminescence (TL), optical absorption, photoluminescence (PL), photo‐stimulated luminescence (PSL), and thermal‐stimulated luminescence (TSL) properties were studied after γ‐ray irradiation at room temperature. The glow curve of the γ‐ray‐irradiated crystal exhibits three peaks at 420, 470 and 525 K. F‐Light bleaching (560 nm) leads to a drastic change in the TL glow curve. The optical absorption measurements indicate that F‐ and V‐centres are formed in the crystal during γ‐ray irradiation. It was attempted to incorporate a broad band of cerium activator into the narrow band of terbium in the KCl host without a reduction in the emission intensity. Cerium co‐doped KCl:Tb crystals showed broad band emission due to the d–f transition of cerium and a reduction in the intensity of the emission peak due to 5D3–7Fj (j = 3, 4) transition of terbium, when excited at 330 nm. These results support that energy transfer occurs from cerium to terbium in the KCl host. Co‐doping Ce3+ ions greatly intensified the excitation peak at 339 nm for the emission at 400 nm of Tb3+. The emission due to Tb3+ ions was confirmed by PSL and TSL spectra. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
18.
Mangesh M. Yerpude Vibha Chopra N.S. Dhoble R.M. Kadam Aleksander R. Krupski S.J. Dhoble 《Luminescence》2019,34(8):933-944
LiMgBO3:Dy3+, a low Zeff material was prepared using the solution combustion method and its luminescence properties were studied using X‐ray diffraction (XRD), scanning electron microscopy (SEM), thermoluminescence (TL), photoluminescence (PL), Fourier transform infrared spectroscopy, and electron paramagnetic resonance (EPR) techniques. Reitvield refinement was also performed for the structural studies. The PL emission spectra for LiMgBO3:Dy3+ consisted of two peaks at 478 due to the 4F9/2→6H15/2 magnetic dipole transition and at 572 nm due to the hypersensitive 4F9/2→6H13/2 electric dipole transition of Dy3+, respectively. A TL study was carried out for both the γ‐ray‐irradiated sample and the C5+ irradiated samples and was found to show high sensitivity for both. Moreover the γ‐ray‐irradiated LiMgBO3:Dy3+ sample showed linearity in the dose range 10 Gy to 1 kGy and C5+‐irradiated samples show linearity in the fluence range 2 × 1010 to 1 × 1011 ions/cm2. In the present study, the initial rise method, various heating rate method, the whole glow curve method, glow curve convolution deconvolution function, and Chen's peak shape method were used to calculate kinetic parameters to understand the TL glow curve mechanism in detail. Finally, an EPR study was performed to examine the radicals responsible for the TL process. 相似文献
19.
Ísis F. Manali Lucas C.V. Rodrigues Adriano H. Braga Douglas Galante Vernica C. Teixeira 《Luminescence》2020,35(4):456-465
Luminescent nanoparticles of Y2O3 doped with europium (Eu) and/or titanium (Ti) were synthesized using modified sol–gel routes. The crystalline cubic phase was confirmed using X‐ray powder diffraction (XRD). Particle morphology and size were evaluated using scanning and transmission electron microscopy. High‐resolution transmission electron microscopy showed that the synthesis method affected the average particle size and the Fourier transform of the images showed the lattice plane distances, indicating that the samples presented high crystallinity degree in accordance with the XRD pattern. The Ti valence was investigated using X‐ray absorption near edge spectroscopy and the tetravalent form was the dominant oxidizing state in the samples, mainly in Eu and Ti co‐doped Y2O3. Optical behaviour was investigated through X‐ray excited optical luminescence and photoluminescence under ultraviolet–visible (UV–vis) and vacuum ultraviolet (VUV) excitation. Results indicated that Eu3+ is the emitting centre in samples doped with only Eu and with both Eu and Ti with the 5D0→7F2 transition as the most intense, indicating Eu3+ in a noncentrosymmetric site. Finally, in the Eu,Ti‐doped Y2O3 system, Ti3+ (or TiIV) excitation was observed but no Ti emission was present, indicating a very efficient energy transfer process from Ti to Eu3+. These results can aid the development of efficient nanomaterials, activated using UV, VUV, or X‐rays. 相似文献
20.
Extraction of Y2O3:Cr3+ nanophosphor by eco‐friendly approach and its suitability for white light‐emitting diode applications
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J. B. Prasanna Kumar G. Ramgopal D. V. Sunitha B. Daruka Prasad H. Nagabhushana Y. S. Vidya K. S. Anantharaju S. C. Prashantha S. C. Sharma K. R. Prabhakara 《Luminescence》2017,32(3):414-424
Cr3+‐doped Y2O3 (0.5–9 mol%) was synthesized by a simple solution combustion method using Aloe vera gel as a fuel/surfactant. The final obtained product was calcined at 750°C for 3 h, which is the lowest temperature reported so far for the synthesis of this compound. The calcined product was confirmed for its crystallinity and purity by powder X‐ray diffraction (PXRD) studies which showed a single‐phase nano cubic phosphor. The particles size estimated by Scherrer formula was in the range of 6–19 nm. The UV–vis spectra showed absorption bands at 198, 272 and 372 nm having band gap energy in the range 4.00–4.26 eV. In order to investigate the possibility of its use in white light emitting display applications, the photoluminescence properties of Cr3+‐doped Y2O3 nanophosphors were studied at an excitation wavelength in the near ultraviolet (UV) light region (361 nm). The emission spectra consisted of emission peaks in the blue (4F9/2 → 6H15/2), orange (4F9/2 → 6H13/2) and red (4F9/2 → 6H11/2) regions. The CIE coordinates (0.33, 0.33) lie in the white light region. Hence Y2O3:Cr3+ can be used for white light‐emitting diode (LED) applications. 相似文献