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1.
A luminescent double perovskite phosphor Sr2YNbO6 doped with Eu3+ crystallized to the monoclinic phase and was synthesized successfully via a conventional high-temperature combustion method. The formation of the crystal structure, phase purity, and surface morphology were studied using X-ray diffraction patterns and scanning electron microscopy. The characteristic vibrations between the atoms of the functional groups present in phosphor were studied using Fourier transform infrared spectra analysis. The luminescence properties of the prepared phosphors were investigated in terms of photoluminescence (PL) and thermoluminescence (TL). PL excitation spectra exhibited charge transfer bands and the characteristic 4f6 transitions of Eu3+. A prominent PL emission was obtained for the phosphor doped with 4 mol% Eu3+ under the 396 nm excitation wavelength. PL emission quenching was observed for the higher doping concentrations due to a multipole–multipole interaction. A highly intense PL emission arose due to the hypersensitive 5D07F2 electric dipole transition of Eu3+ that dominated the emission spectra. The thermal stability of the phosphor was examined through temperature-dependent PL. The TL properties of the Sr2YNbO6 double perovskites irradiated with a 90Sr beta source at different doses were measured. The double perovskite phosphors under study showed a linear dose–response with increasing beta dose, ranging from 1 Gy to 10 Gy. Trapping parameters of the TL glow curves were determined using Chen's peak shape method and computerized glow curve deconvolution (CGCD). CGCD fitting of the TL glow curves revealed that it was consisted of three major peaks and followed second-order kinetics. The estimated activation energies were determined using different methods and were comparable and significant.  相似文献   

2.
Dy3+ and Eu3+ activated Ca3Y2Si3O12 phosphors were synthesized by the solid‐state synthesis method. The phosphors were characterized by X‐ray diffraction (XRD), mechanoluminescence (ML), thermoluminescence (TL) and photoluminescence (PL) to determine structure and luminescence. For ML glow curves, only one peak was observed, as only one type of luminescence centre was formed during irradiation. The Ca3Y2Si3O12:Dy3+ TL glow curve showed a single peak at 151.55°C and the Ca3Y2Si3O12:Eu3+ TL glow curve peaked at 323°C with a small peak at 192°C, indicating that two types of traps were activated. The trapping parameters for both the samples were calculated using Chen's peak shape method. Dy3+‐activated Ca3Y2Si3O12 showed emission at 482 and 574 nm when excited by a 351 nm excitation wavelength, whereas the Eu3+‐activated Ca3Y2Si3O12 phosphor PL emission spectra showed emission peaks at 613 nm, 591 nm, 580 nm when excited at 395 nm wavelength. When excited at 466 nm, prominent emission peaks were observed at their respective positions with very slight shifts. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

3.
A blue CaMgSi2O6:Eu2+ phosphor was prepared by the solid‐state reaction method and the phosphor characterized in terms of crystal structure, particle size, photoluminescence (PL), thermoluminescence (TL) and mechanoluminescence (ML) properties using X‐ray diffraction (XRD), transmission electron microscopy (TEM), PL spectroscopy, TLD reader and ML impact technique. The XRD result shows that phosphor is formed in a single phase and has a monoclinic structure with the space group C2/c. Furthermore, the PL excitation spectra of Eu2+‐doped CaMgSi2O6 phosphor showed a strong band peak at 356 nm and the PL emission spectrum has a peak at 450 nm. The depths and frequency factors of trap centers were calculated using the TL glow curve by deconvolution method in which the trap depths were found to be 0.48 and 0.61 eV. The formation of CaMgSi2O6:Eu2+ phosphor was confirmed by Fourier transform infrared spectroscopy. The ML intensity increased linearly with the impact velocity of the piston used to deform the phosphor. It was shown that the local piezoelectricity‐induced electron bombardment model is responsible for the ML emission. Finally, the optical properties of CaMgSi2O6:Eu2+ phosphors are discussed. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

4.
Photoluminescence (PL) and thermoluminescence (TL) properties of rare earth (RE) ion (RE = Dy3+, Sm3+, Ce3+, Tb3+) activated microcrystalline BaMgP2O7 phosphors are presented in this work. Non‐doped and doped samples of BaMgP2O7 were prepared using a solid state diffusion method and characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), PL and TL. The XRD measurement confirmed the phase purity of the BaMgP2O7 host matrix. The average particle size was found through SEM measurement to be around 2 μm. All activators using the PL technique displayed characteristic excitation and emission spectra that corresponded to their typical f → f and f → d transitions respectively. Thermoluminescence measurements showed that BaMgP2O7:RE (RE = Dy3+, Sm3+, Tb3+, Ce3+) and co‐doped BaMgP2O7:Ce3+,Tb3+ phosphors have also TL behaviour.  相似文献   

5.
In this article, photoluminescence (PL) and thermoluminescence (TL) properties of ZrO2, ZrO2:Dy3+, ZrO2:Dy3+–Gd3+, ZrO2:Dy3+–Yb3+, ZrO2:Dy3+–Er3+, and ZrO2:Dy3+–Sm3+ phosphors synthesized by the Pechini method were investigated. The crystal structure, thermal properties, morphology, PL and TL properties were investigated using X-ray powder diffraction (XRD), differential thermal analysis/thermogravimetric analysis (DTA/TGA), scanning electron microscopy (SEM), PL and TL, respectively. The room temperature emission bands corresponding to 4F9/2 → 6HJ (J = 9/2, 11/2, 13/2 and 15/2) transitions of Dy3+ ions were measured. The phosphors were analysed using TmTSTOP, variable dose, and computerized glow curve fitting methods. Reusability, dose–response, and fading characteristics were investigated. The phosphors have a natural TL emission that vanished by heating treatment. Moreover, new peaks with similar properties to the natural emissions were observed after high-dose irradiation and long-term fading experiments. The glow curves of the phosphors have 13 individual peaks and many low- and high-temperature satellite peaks. The origin of the peaks is ZrO2 host material and doping with rare-earth ions (Gd3+, Dy3+, Yb3+, Er3+ and Sm3+) does not lead to a new glow peak. The dopants cause drastic changes in individual peak intensities of ZrO2.The initial fading rates of all the phosphors are relatively fast, but they slow down as time goes on.  相似文献   

6.
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 5D37Fj (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   

7.
Calcium aluminate phosphors activated by Dy3+ have been prepared by a combustion method at a temperature of 600°C. Photoluminescence (PL) and thermoluminescence (TL) properties of gamma‐irradiated Dy‐doped calcium aluminate were investigated. The PL spectrum shows a broad peak around 488 nm and 573 nm, under 347 nm excitation. Thermoluminescence studies were performed for different concentrations of Dy. Optimum intensity of photoluminescence was found for 0.02 mol% concentration of Dy. It was found that initially the peak TL intensity increases with increasing concentration of Dy in the CaAl2O4 host, attains a maximum value for 0.05 mol% concentration and decreases with further increase in the doping concentration due to concentration quenching. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

8.
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   

9.
Dy3+-doped CaY2Al4SiO12 phosphors were prepared using the sol–gel method. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and energy dispersive spectroscopy analyses (EDS) were used to analyse the crystal structure, morphology, and elemental composition of the prepared samples. The luminescence behaviour of the sample was investigated using photoluminescence (PL) and thermoluminescence (TL) techniques. The prepared CaY2Al4SiO12:xDy3+ phosphor showed a characteristic blue and yellow emission at ~480 and 583 nm, respectively, with an excitation wavelength of 350 nm. The most intense PL emission was found for a 4 mol% doping concentration of Dy3+ ions. The CIE diagram of the phosphor showed bluish-white colour emission. For TL studies, the prepared phosphors were irradiated with a 60Co γ (gamma) source and the TL glow curve of the CaY2Al4SiO12:0.04Dy3+ phosphor showed three overlapped peaks. For the Gaussian peaks, Chen's peak shape method was applied to determine the kinetic parameters of the samples.  相似文献   

10.
KMgSO4F:Ce and KMgSO4F:Mn phosphors were prepared by a wet chemical method and studied for their photoluminescence (PL) and thermoluminescence (TL) characteristics. PL emission of KMgSO4F:Ce peaked at around 440 nm for the excitation at 377 nm due to 5d → 4f transition, while KMgSO4F:Mn had a peak at 540 nm for an excitation at 363 nm and 247 nm due to 4T1g6A1g transition. The phosphors also showed good thermoluminescence characteristics when they were exposed to γ‐rays at a 5 Gy dose at the rate of 0.36 kGyh?1. KMgSO4F:Ce exhibited a single thermoluminescence (TL) peak at around 167 °C and KMgSO4F:Mn also exhibited a single TL peak at around 177 °C. Possible trapping parameters such as order of kinetics (b), the geometrical factor (μg), the frequency factor (s) and the activation energy were also evaluated by Chen's half width method. This article discusses fundamental PL and TL characteristics in inorganic fluoride material activated by Ce3+ and Mn2+ ions and prepared by a wet chemical method. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

11.
Thermoluminescence (TL) materials are widely used in radiation measurements. The best‐known applications of TL materials are in the dosimetry of ionizing radiation, and in CTV screen phosphors, scintillators, X‐ray laser materials, etc. The TL glow curve and its kinetic parameters for annealed LaPO4 at different constant temperatures and for Dy3+‐doped LaPO4 phosphors irradiated by gamma‐rays are reported here. The samples were irradiated using a 60Co gamma‐ray source at a dose of 10 Gy and the heating rate used for TL measurements was 5ºC/s. The samples were characterized using X‐ray diffraction (XRD), Fourier transform infrared, transmission electron microscopy and TL techniques. The XRD pattern shows that the prepared phosphor has a good crystalline structure with an average crystallite size of ~ 18 nm. The samples show good TL peaks for 0.05, 0.1 and 0.2 mole % doping concentrations of Dy3+ ions and anneal above 400ºC. The TL glow curve characteristics of annealed LaPO4 and Dy3+‐doped LaPO4 were analyzed and trapping parameters calculated using various methods. All TL glow curves obey the second‐order kinetics with a single glow peak, which reveals that only one set of trapping parameter is set for a particular temperature. The TL sensitivity was found to depend upon the annealing temperature and Dy3+ doping concentration. The prepared sample may be a new nano phosphor and be useful in TL dosimetry. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

12.
Ce3+‐doped calcium aluminosilicate phosphor was prepared by a combustion‐assisted method at an initiating temperature of 600°C. Structural characterization was carried out using X‐ray diffraction (XRD) and scanning electron microscopy (SEM). The absorption spectra of Ca2Al2SiO7:Ce3+ showed an absorption edge at 230 nm. The optical characterization of Ca2Al2SiO7:Ce3+ phosphor was investigated in a fracto‐mechanoluminescence (FML) and thermoluminescence (TL) study. The peak of ML intensity increased as the height of impact of the moving piston increased. The TL intensity of Ca2Al2SiO7:Ce3+ was recorded for different exposure times of UV and γ‐irradiation and it was observed that TL intensity was maximum for a UV irradiation time of 30 min and for a γ‐dose of 1180 Gy. The TL intensity had three peaks for UV irradiation at temperatures 82°C, 125°C and 203°C. Also the TL intensity had a single peak at 152°C for γ‐irradiation. The TL and ML emission spectra of Ca2Al2SiO7:Ce3+ phosphor showed maximum emission at 400 nm. The possible mechanisms involved in the TL and ML processes of the Ca2Al2SiO7:Ce3+ phosphor are also explained. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

13.
A new Na3Ca2(SO4)3F: Ce3+ phosphor synthesized by a solid state diffusion method is reported. The photoluminescence study showed a single high intensity emission peak at 307 nm wavelength when excited by UV light of wavelength 278 nm. An unresolved peak of comparatively less intensity was also observed at 357 nm along with the main peak. The characteristic emission of dopant Ce in Na3Ca2(SO4)3F phosphor clearly indicated that it resides in the host lattice in trivalent form. The emission peak can be attributed to 5d → 4f transition of rare earth Ce3+. The prepared sample is also characterized for its thermoluminescence properties. The TL glow curve of prepared sample showed a single broad peak at 147°C. The trapping parameters are also evaluated by Chen's method. The values of trap depth (E) and frequency factor (s) were found to be 0.64 ± 0.002 eV and 1.43 × 107 s–1 respectively. The study of PL and TL along with evaluation of trapping parameters has been undertaken and discussed for the first time. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

14.
A series of Ce3+ ion single‐doped Ca2Al2SiO7 phosphors was synthesized by a combustion‐assisted method at an initiating temperature of 600 °C. The samples were annealed at 1100 °C for 3 h and their X‐ray diffraction patterns confirmed a tetragonal structure. The phase structure, particle size, surface morphology and elemental analysis were analyzed using X‐ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscopy (SEM) and energy dispersive X‐ray (EDX) spectroscopy techniques. Thermoluminescence (TL) intensity increased with increase in ultraviolet (UV) light exposure time up to 15 min. With further increase in the UV irradiation time the TL intensity decreases. The increase in TL intensity indicates that trap concentration increased with UV exposure time. A broad peak at 121 °C suggested the existence of a trapping level. The peak of mechanoluminescence (ML) intensity versus time curve increased linearly with increasing impact velocity of the moving piston. Mechanoluminescence intensity increased with increase in UV irradiation time up to 15 min. Under UV‐irradiation excitation, the TL and ML emission spectra of Ca2Al2SiO7:Ce3+ phosphor showed the characteristic emission of Ce3+ peaking at 400 nm (UV–violet) and originating from the Ce3+ transitions of 5d‐4f (2F5/2 and 2F7/2). The photoluminescence (PL) emission spectra for Ca2Al2SiO7:Ce3+ were similar to the ML/TL emission spectra. The mechanism of ML excitation and the suitability of the Ca2Al2SiO7:Ce3+phosphor for radiation dosimetry are discussed. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

15.
Eu2+ and Tb3+ singly doped and co‐doped LaAl11O18 phosphors were prepared by a combustion method using urea as a fuel. The phase structure and photoluminescence (PL) properties of the prepared phosphors were characterized by powder X‐ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence excitation and emission spectra. When the content of Eu2+ was fixed at 0.01, the emission chromaticity coordinates could be adjusted from blue to green region by tuning the contents of Tb3+ ions from 0.01 to 0.03 through an energy transfer (ET) process. The fluorescence data collected from the samples with different contents of Tb3+ into LaAl11O18: Eu, show the enhanced green emission at 545 nm associated with 5D47F5 transitions of Tb3+. The enhancement was attributed to ET from Eu2+ to Tb3+, and therefore Eu2+ ion acts as a sensitizer (an energy donor) while Tb3+ ion as an activator. The ET from Eu2+ to Tb3+ is performed through dipole–dipole interaction. The ET efficiency and critical distance were also calculated. The present Eu2+–Tb3+ co‐doped LaAl11O18 phosphor will have potential application for UV convertible white light‐emitting diodes. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

16.
Eu2+‐doped Ba3Si6O12N2 phosphors were prepared successfully via a modified solid‐state diffusion method. The phosphors were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence measurements. These phosphors were effectively excited at 355 nm and an intense emission peaking in the range 480 nm to 525 nm in the blue region was observed. The optimized dopant concentration was determined to be 1 mol% of Eu2+ ion. The colour coordinates for phosphor were found to be (0.196, 0.326) in the blue region. This phosphor may find application for near‐ultraviolet (NUV) excited lamp phosphors. The thermoluminescence study shows the complex glow curve. Trapping parameters (activation energy and frequency factor) were calculated for individual deconvoluted peaks by Chen's peak shape method, the initial rise method and the whole glow peak method. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

17.
A series of single‐phase phosphors based on Na6Mg(SO4)4 (Zeff = 11.70) doped with Dy and Eu was prepared by the wet chemical method. The photoluminescence (PL) and thermoluminescence (TL) properties of Dy3+‐ and Eu3+‐activated Na6Mg(SO4)4 phosphors were investigated. The characteristic emissions of Dy3+ and Eu3+ were observed in the Na6Mg(SO4)4 host. The TL glow curve of the Na6Mg(SO4)4:Dy phosphor consisted of a prominent peak at 234°C and a very small hump at 158°C. The TL sensitivity of the Na6Mg(SO4)4:Dy phosphor was found to be four times less than the commercialized CaSO4:Dy phosphor. The TL dose–response of the Na6Mg(SO4)4:Dy phosphor was studied from a dose range of 5–10 kGy and the linear dose–response was observed up to 1 kGy which is good for a microcrystalline phosphor. Trapping parameters for both the samples were calculated using the Initial Rise and Chen's peak shape methods.  相似文献   

18.
We present a new phosphor material, BaAlBO3F2 doped with Eu2+ ions, having emission in the UVA region. The phosphor material is prepared by a simple wet chemical method. Phase confirmation was carried out using the Rietveld refinement program which shows that BaAlBO3F2:Eu2+ has an hexagonal crystal system. Using a Fourier transform infrared spectroscopy graph, we studied the bond stretching present in the phosphor material. Photoluminescence (PL) characterization, carried out using a RF spectrofluorophotometer, shows two types of PL excitation and emission. Before reduction, emission is in the blue region at 431 nm; after reduction, excitation is at 258 nm and emission is at 361 nm, which is in the UVA region. Some thermoluminescence (TL) studies were carried out in this material for the first time, for example, determination of the trapping parameters, linearity, fading, glow curve convolution and deconvolution (GCCD) function for curve fitting and the Tm–Tstop method for confirmation of the trapped centers in the TL glow peak. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

19.
LaBSiO5 phosphors doped with Ce3+ and Tb3+ were synthesized using the conventional solid‐state method at 1100 °C. The phase purity and luminescent properties of these phosphors are investigated. LaBSiO5:Tb3+ phosphors show intense green emission, and LaBSiO5 phosphors doped with Ce3+ show blue–violet emission under UV light excitation. LaBSiO5 phosphors co‐doped with Ce3+ and Tb3+ exhibit blue–violet and green emission under excitation by UV light. The blue–violet emission is due to the 5d–4f transition of Ce3+ and the green emission is ascribed to the 5D47 F5 transition of Tb3+. The spectral overlap between the excitation band of Tb3+ and the emission band of Ce3+ supports the occurrence of energy transfer from Ce3+ to Tb3+, and the energy transfer process was investigated. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

20.
The photoluminescence and thermoluminescence characteristics of rare earths (Dy or Ce) activated LiCaBO3 phosphors have been studied. Phosphors were synthesized by modified solid state synthesis. The phosphors were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL) and thermoluminescence (TL) for structural, morphological and luminescence studies. Dy3+ activated LiCaBO3 shows emission at 486 and 577 nm due to 4 F9/26H15/2 and 4 F9/26H13/2 transition, respectively, whereas the PL emission spectra of Ce3+ activated LiCaBO3 phosphor shows a broad band peaking at 432 nm, which is due to the transition from 5d level to the ground state of the Ce3+ ion. The thermoluminescence study was also carried out for both these phosphors for γ‐ray irradiation and carbon beam irradiation. Linearity was studied for a 0.4–3.1 Rad dose γ‐rays. Linear behaviour over this dose range was observed. Gamma ray‐irradiated phosphors were shown to be negligible fading upon storage. All the samples were also studied for 75 MeV C5+ ion beam exposure in the range of 3.75 × 1012 – 7.5 × 1013 ion cm–2 fluence. In addition to this, trapping parameters of all the samples were also calculated using Chen's peak shape method. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

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