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1.
Tirath Ram Neeraj Verma Jagjeet Kaur Abhishek Kumar Misra Vikas Dubey Neha Dubey Ankush Vij Myla Chimpiri Rao 《Luminescence》2023,38(9):1591-1596
Here, the synthesis and luminescence analysis of the Tb3+-activated phosphor were reported. The CaY2O4 phosphors were synthesized using a modified solid-state reaction method with a variable doping concentration of Tb3+ ion (0.1–2.5 mol%). As synthesized, the phosphor was characterized using Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction analysis techniques for the optimized concentration of doping ions. The prepared phosphor showed a cubic structure, and FTIR analysis confirmed functional group analysis. It was discovered that the intensity of 1.5 mol% was higher than at other concentrations after the photoluminescence (PL) excitation and emission spectra were recorded for different concentrations of doping ions. The excitation was monitored at 542 nm, and the emission was monitored at 237 nm. At 237 nm excitation, the emission peaks were found at 620 nm (5D4→7F3), 582 nm (5D4→7F4), 542 nm (5D4→7F5), and 484 nm (5D4→7F6). The 1931 CIE (x, y) chromaticity coordinates showed the distribution of the spectral region calculated from the PL emission spectra. The values of (x = 0.34 and y = 0.60) were very close to dark green emission. Therefore, the produced phosphor would be very useful for light-emitting diode (green component) applications. Thermoluminescence glow curve analysis for various concentrations of doping ions and various ultraviolet (UV) exposure times was carried out, and a single broad peak was found at 252°C. The computerized glow curve deconvolution method was used to obtain the related kinetic parameters. The prepared phosphor exhibited an excellent response to UV dose and could be useful for UV ray dosimetry. 相似文献
2.
Zeng‐Mei Li Li‐Gang Deng Shan‐Cang Zhao Shu‐Qiu Zhang Chang‐Ying Guo Jing‐Yun Liang Hui Yue Chun‐Yan Wan 《Luminescence》2016,31(2):462-467
The antimonate compound La3SbO7 has high chemical stability, lattice stiffness and thermal stability. Orange–red‐emitting antimonate‐based phosphors La3SbO7:xSm3+ (x = 0.02, 0.05, 0.08, 0.10, 0.15, 0.20 and 0.25) were synthesized. The phase structure and photoluminescence properties of these phosphors were investigated. The emission spectrum obtained on excitation at 407 nm contained exclusively the characteristic emissions of Sm3+ at 568, 608, 654 and 716 nm, which correspond to the transitions from 4G5/2 to 6H5/2, 6H7/2, 6H9/2 and 6H11/2 of Sm3+, respectively. The strongest emission was located at 608 nm due to the 4G5/2→6H7/2 transition of Sm3+, generating bright orange–red light. The critical quenching concentration of Sm3+ in La3SbO7:Sm3+ phosphor was determined as 10% and the energy transfer between Sm3+ was found to be through an exchange interaction. The International Commission on Illumination chromaticity coordinates of the La3SbO7:0.10Sm3+ phosphors are located in the orange–red region. The La3SbO7:Sm3+ phosphors may be potentially used as red phosphors for white light‐emitting diodes. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
3.
Mocharla Purna Durga Parimala M. C. Rao K. Suresh Ch. Vijay Anil Dai K. V. R. Murthy Vikas Dubey 《Luminescence》2022,37(8):1284-1289
In this paper, we present new aspects of Sm3+-doped pure Li2CaSiO4 as a suitable candidate for white light emitting diode (WLED) applications. The samples were mainly prepared using a conventional modified solid-state synthesis technique. The structural studies were done using X-ray diffraction and Rietveld refinement. Instruments such as a scanning electron microscope (SEM) were used to obtain information about the morphology of the as-prepared samples. Photoluminescence (PL) analysis of phosphor samples for variable concentrations of doping ions with variable excitations were presented. When doped with Sm3+ in host Li2CaSiO4 it emitted intense blue, green and red emissions and a more intense red emission peak (605 nm) under 408 nm excitation (near-UV–blue). Our study shows that the as-prepared phosphor may be useful for optical devices and mainly for WLEDs. The corresponding transitions of doping ions and concentration quenching effect were studied in detail. The 1931 Commission Internationale de l'Eclairage (x, y) chromaticity coordinates showed the distribution of spectral regions calculated from PL emission spectra and this was found (0.63, 0.36) in the red region, so the phosphor may be useful for near-UV–blue excited WLED applications. 相似文献
4.
Here we report the synthesis and structural, morphological, and photoluminescence analysis of white‐ and blue‐light‐emitting Dy3+‐ and Tm3+‐doped Gd2Ti2O7 nanophosphors. Single‐phase cubic Gd2Ti2O7 nanopowders consist of compact, dense aggregates of nanoparticles with an average size of ~25 nm for Dy3+‐doped and ~50 nm for Tm3+‐doped samples. The photoluminescence results indicated that ultraviolet (UV) light excitation of the Dy3+‐doped sample resulted in direct generation of white light, while a dominant yellow emission was obtained under blue‐light excitation. Intense blue light was obtained for Tm3+‐doped Gd2Ti2O7 under UV excitation suggesting that this material could be used as a blue phosphor. 相似文献
5.
In this study, the thermoluminescence (TL) characteristics of Ag‐doped and undoped lithium tetraborate (Li2B4O7, LTB) materials, grown using the Czochralski method, were reported. The TL properties of LTB:Ag, such as glow curve structure, dose response, fading and reproducibility, were investigated. The glow curve of the Li2B4O7:Ag single crystal consists of four peaks located at approximately 75, 130, 190 and 275°C; in undoped LTB, the single crystal shows a broad glow curve with peaks at 65, 90, 125, 160 and 190°C using a heating rate of 5°C/s in the 50–350°C temperature region. The high temperature peak of Ag‐doped sample at 275°C has a nonlinear dose response within the range from 33 mGy to 9 Gy. There is a linear response in the range of 33–800 mGy; after which, a sublinear region appears up to 9 Gy for Ag‐doped LTB single crystal. For undoped single crystal, the dose response is supralinear for low doses and linear for the region between 1 and 9 Gy. The thermal fading ratio of the undoped material is almost 60% for the high temperature peak after 7 days. Ag‐doped LTB single crystal exhibits different behaviour over a period of 7 days. 相似文献
6.
An intense green luminescent Na2Ca(PO4)F:Mn2+ phosphor has been prepared at high temperature by reduction treatment in a charcoal environment. The emission band of Mn2+ was obtained at around 522 nm (green) under 259 nm excitation. Enhancement in emission intensity arising from the thermal treatment is reported. The intense emission of the spectrum was assigned to electronic transitions 4T1 → 6A1 of Mn2+ ions. Intense PL emission suggested that temperature employed plays an important role in the present matrix. X‐ray diffraction pattern, photoluminescence and morphology by SEM of the host lattice of phosphors at different temperatures have been reported in this paper. The results obtained show that the present phosphor has potential for application in green emitting phosphors for the lamp industry. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
7.
Different metal complexes of Alq3 (K+, Sr2+, Ca2+ and Mg2+) were synthesized by the precipitation method. The characterization of photoluminescence showed that presence of Mg2+ ion enhances photoluminescence of Alq3 phosphor. The emission spectra are observed at 560 nm when excited at a wavelength of 440 nm. The phosphor is excited at a longer wavelength in the blue region of small energy, so that it could be used as lamp phosphor. It is observed that the prepared phosphor AlMgq5 is more suitable than Alq3. The ionic radii of K+, Sr2+, Ca2+ and Mg2+ ions are in decreasing order. Therefore, the remarkable properties of AlMgq5 could be considered as promising materials as opto‐ or optoelectronic materials. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
8.
CdTe quantum dots, 3.28 nm in size, were synthesized using a one‐step method in an aqueous medium. The CdTe quantum dots were successfully employed as hybrid phosphors for white light‐emitting diode (LED) devices by combining them with yellow‐emitting YAG:Ce phosphor. The color‐rendering index value and International Commission on illumination coordinates for hybrid phosphor white LEDs were 75 and (x = 0.30, y = 0.29), respectively. Compared with conventional phosphors, semiconductor quantum dots have larger band gap energy and broader absorption features, and can be excited more efficiently by optical pumping sources. The results confirmed that the high color‐rendering index value of the white LED was due to the CdTe quantum dots introduced in the hybrid phosphor system. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
9.
The structural, surface morphological, optical absorption and emission features of Y2O3:Ce (0%–5%) were studied. The samples had a body-centred cubic crystal structure. The undoped sample had a crystallite size of 29.03 nm, and it varied after doping with Ce. The grain size of the samples varied from 23.00 to 50.78 nm. All the samples exhibited a strong absorption band at 206 nm due to F-centre absorption and absorption involving the delocalised bands. In addition, the doped samples exhibited a secondary band at ~250 nm due to 4f → 5d transitions of Ce3+ ions. The optical bandgap of the undoped sample was found to be ~5.37 eV, and it decreased to 5.20 eV with an increase in Ce concentration to 5%. The undoped sample under 350-nm excitation exhibited a broad photoluminescence (PL) emission band with the maxima at 406 nm and a secondary band at 463 nm. In contrast, multiple PL peaks were centred at ~397, 436, 466, 488 and 563 nm in all the doped samples. The average lifetime of the emission band at 406 nm was 1.05 ns and that of the emission band at ~466 nm was 1.63 ns. The material has potential for solid-state lighting applications. 相似文献
10.
Li3PO4 phosphor was prepared using a modified solid‐state diffusion technique. In this work, photoluminescence, lyoluminescence and mechanoluminescence studies were carried out in a Li3PO4 microcrystalline powder doped with different rare earths. In photoluminescence studies, characteristic emission of Ce and Eu was observed. The lyoluminescence glow curves of Li3PO4 microcrystals show that lyoluminescence intensity initially increases with time and then decreases exponentially. The decay time consists of two components for all masses. The dependence of decay time, especially the longer component, on mass has been investigated. Experiments on γ‐irradiated crystals have proved that the light emission originates from the recombination of released F‐centres with trapped holes (V2‐centres) at the sulfuric acid–solid interface. Incorporation of bivalent alkali in solid lithium phosphate leads to an enhancement of lyoluminescence. A possible explanation for the experimental results has been attempted. The phosphor has a mechanoluminescence single glow peak. Mechanoluminescence intensity under various loading conditions was investigated. It is observed that mechanoluminescence intensity increases with increasing impurity concentration and increasing piston impact velocity. The results may be considered as only being of academic interest in solid‐state materials. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
11.
Y2‐xGeMoO8:REx (RE = Eu, Tb) phosphors were synthesized using a facile sol–gel method. The morphology and structure of the phosphors were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X‐ray diffraction (XRD); while their luminescent properties were investigated by photoluminescence (PL) spectrometry. Our results reveal that all of these Y2‐xGeMoO8:REx (RE = Eu, Tb) phosphors adopted the tetragonal phase, belonging to Scheelite (CaWO4) structure. The obtained YGeMoO8:Eu phosphors exhibit a strong emission in the red light range which can be assigned to the 5D0 → 7F2 transition of Eu3+ when it is excited at 459 nm. Under 392 and 489 nm excitation, the YGeMoO8:Tb phosphors present predominant green emission (5D4 → 7F5) at 540 nm. The highest emission of the phosphors can be achieved by adjusting the doping concentration to be 0.25 for Eu3+ and 0.15 for Tb3+, respectively. The promising luminescence properties of these materials indicate that they can be potentially applied to white‐light‐emitting diodes. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
12.
The new borate phosphor CaB2O4:Eu3+ was synthesized by solid‐state method and their photoluminescence properties were investigated. The results show that the pure phase of CaB2O4 could be available at 900°C, CaB2O4:Eu3+ phosphor could be effectively excited by the near ultraviolet light (NUV) (392 nm), and the luminescent intensity of CaB2O4:Eu3+ phosphor reached to the highest when the doped‐Eu3+ content was 4 mol%. The emission spectra of CaB2O4:Eu3+ phosphor could exhibit red emission at 612 nm and orange emission at 588 nm, which are ascribed to the 5D0–7F2 and 5D0–7F1 transitions of Eu3+ ions. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
13.
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 4S3/2 → 4I15/2 and the weaker transition at 594 nm is due to the transition 4 F9/2 → 4I15/2. 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
14.
Kishore Kumar Aitha Dantala Dinakar K. V. R. Murthy A. S. Sai Prasad Divi Haranath 《Luminescence》2024,39(1):e4623
Direct white light emitting phosphors play a significant role in the display industry due to their ability to improve the quality, efficiency, and versatility of lighting sources used in most of the displays. The currently investigated phosphor SrZr2CaLa2O8:Eu3+ was prepared by a conventional solid-state reaction method. It has been observed that the stoichiometric ratio of all precursors plays an important role in determining the characteristics of the final phosphor. From X-ray diffraction (XRD) analysis, the phosphor was observed to have a hexagonal phase and a crystal size of ~28 nm. Scanning electron microscopy (SEM) observations revealed a cluster of rod-like structures with an average diameter of ~0.2 μm. The excitation peak maximum observed at 280 nm is due to charge transfer between Eu3+-O2− ions. The energy transitions 7F0 → 5L6 and 7F0 → 5D2 are responsible for the appearance of other excitation peaks at ultraviolet (UV) (395 nm), blue (~467 nm), green (~540 nm), orange (~590 nm), and red (~627 nm) attributed to 5D0 → 7FJ (J = 0–4) transitions of europium ion (Eu3+). The Commercial International de I'Eclairage (CIE) chromaticity coordinates were estimated to be (0.37, 0.0.33) and (0.67, 0.33) for the emissions corresponding to 395 and 590 nm, respectively. The characteristic emissions of Eu3+ ions allow this novel phosphor to be used to generate direct white light in light-emitting diodes (LEDs), which is otherwise difficult to achieve in single-component systems. 相似文献
15.
Hammam Abdurabu Thabit Abd Khamim Ismail Norlaili A. Kabir Mohammad Hasan Abu Mhareb Abdulmajeed Muidh Al Mutairi Abdullah Bafaqeer Yasser Alajerami Mohammad Ibrahim Abualsayyed 《Luminescence》2024,39(2):e4683
This work explores the thermoluminescence (TL) and photoluminescence (PL) properties of Ag/Y co-doped zinc oxide (ZnO) nanophosphor. The proposed dosimeter was prepared by the coprecipitation method and sintered at temperatures from 400°C to 1000°C in an air atmosphere. Raman spectroscopy was studied to investigate the structural features of this composition. The new proposed dosimeter revealed two peaks at 150°C and 175°C with a small shoulder at high temperature (225°C). The PL spectrum showed strong green emissions between 500 to 550 nm. The Raman spectrum showed many bands related to the interaction between ZnO, silver (Ag), and yttrium oxide (Y2O3). The rising sintering temperature enhanced the TL glow curve intensity. The Ag/Y co-doped ZnO nanophosphor showed an excellent linearity index within a dose from 1 to 4 Gy. The minimum detectable dose (MDD) of the Ag/Y co-doped ZnO nanopowder (pellets) equaled 0.518 mGy. The main TL properties were achieved in this work as follows: thermal fading (37% after 45 days at 1 and 4 Gy), optical fading (53% after 1 h and 68% after 6 h by exposure to sunlight), effective atomic number (27.6), and energy response (flat behavior from 0.1 to 1.3 MeV). Finally, the proposed material shows promising results nominated to be used for radiation measurements. 相似文献
16.
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
17.
The thermoluminescence (TL) characterizations of γ‐irradiated KCl:Dy phosphor for radiation dosimetry are reported. All phosphors were synthesized via a wet chemical route. Minimum fading of TL intensity is recorded in the prepared material. TL in samples containing different concentrations of Dy impurity was studied at different γ‐irradiation doses. Peak TL intensities varied sublinearly with γ‐ray dose in all samples, but were linear between 0.08 to 0.75 kGy for the KCl:Dy (0.1 mol%) sample. This material may be useful for dosimetry within this range of γ‐ray dose. TL peak height was found to be dependant on the concentration (0.05–0.5 mol%) of added Dy in the host. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
18.
Ishwar Prasad Sahu 《Luminescence》2017,32(3):364-374
In the present article we report europium‐doped strontium ortho‐silicates, namely Sr2SiO4:xEu3+ (x = 1.0, 1.5, 2.0, 2.5 or 3.0 mol%) phosphors, prepared by solid state reaction method. The crystal structures of the sintered phosphors were consistent with orthorhombic crystallography with a Pmna space group. The chemical compositions of the sintered phosphors were confirmed by energy dispersive X‐ray spectroscopy (EDS). Thermoluminescence (TL) kinetic parameters such as activation energy, order of kinetics and frequency factors were calculated by the peak shape method. Orange‐red emission originating from the 5D0–7FJ (J = 0, 1, 2, 3) transitions of Eu3+ ions could clearly be observed after samples were excited at 395 nm. The combination of these emissions constituted orange‐red light as indicated on the Commission Internationale de l'Eclairage (CIE) chromaticity diagram. Mechanoluminescence (ML) intensity of the prepared phosphor increased linearly with increasing impact velocity of the moving piston that suggests that these phosphors can also be used as sensors to detect the stress of an object. Thus, the present investigation indicates that the piezo‐electricity was responsible for producing ML in the prepared phosphor. 相似文献
19.
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
20.
Jie Liu Zhan‐Chao Wu Ping Wang Yong‐Mei Mei Man Jiang Shao‐Ping Kuang 《Luminescence》2014,29(7):868-871
Charge compensation is an effective way to eliminate charge defects and improve the luminescent intensity of phosphors. In this paper, a new green‐emitting phosphor ZnB2O4:Tb3+ was prepared by solid‐state reaction at 750°C. The effects of Tb3+ doping content and charge compensators (Li+, Na+ or K+) on photoluminescence properties of ZnB2O4:Tb3+ were investigated. X‐ray powder diffraction analysis confirms the sample has cubic structure of ZnB2O4. The excitation and emission spectra indicate that this phosphor can be excited by near ultraviolet light at 378 nm, and exhibits bright green emission with the highest peak at 544 nm corresponding to the 5D4→7F5 transition of Tb3+. The critical quenching concentration of Tb3+ in ZnB2O4 host is 8 mol%. The results of charge compensation show that the emission intensity can be improved by Na+ and K+. Specifically, K+ is the optimal one for ZnB2O4:Tb3+. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献