共查询到20条相似文献,搜索用时 15 毫秒
1.
S. M. Levshov I. V. Berezovskaya N. P. Efryushina B. I. Zadneprovskii V. P. Dotsenko 《Inorganic Materials》2011,47(3):285-289
We have studied the luminescence spectra of Li2Sr1 − x
Eu
x
SiO4 (x = 0.0001–0.01) solid solutions prepared by solid-state reactions and a sol-gel process in a reducing atmosphere. The spectra
show a broad band in the range 500–700 nm, centered at 578 nm, which is due to the 4f
65d → 4f
7 transition. The luminescence excitation spectrum shows, in addition to bands due to Eu2+ 4f
7 → 4f
65d transitions, a strong band centered at 174 nm, attributable to absorption in the SiO44− group. 相似文献
2.
Ehsan Shafia Alireza Aghaei Masoud Bodaghi Mohammadreza Tahriri 《Journal of Materials Science: Materials in Electronics》2011,22(8):1136-1142
In this research, we reported the synthesis of Eu2+ and Dy3+ co-doped SrAl2O4 phosphor nanopowders with high brightness and long afterglow by urea-nitrate solution combustion synthesis (SCS) at 600 °C,
followed by heating the resultant combustion ash at 1,200 °C in a weak reductive atmosphere (5% H2 + 95% N2). The broad-band UV-excited luminescence of the SrAl2O4: Eu2+, Dy3+ nanopowders was observed at λ
max = 517 nm due to transitions from the 4f65d1 to the 4f7 configuration of the emission center (Eu2+ ions). The excitation spectra consist of 240- and 254 nm broad peaks. Finally, it was found that the optimum ratio of urea
is 2.5 times higher than theoretical quantities for the best emission condition of SrAl2O4: Eu2+, Dy3+ phosphor nanopowders. 相似文献
3.
A. N. Georgobiani B. G. Tagiev O. B. Tagiev S. A. Abushov F. A. Kazymova T. Sh. Gashimova Xu Xurong 《Inorganic Materials》2009,45(2):116-122
The photoluminescence (PL) spectra and Eu2+ excited state lifetime of EuGa2S4 and EuGa2S4:Er3+ have been studied in the range 78–500 K. The spectra show a band at 545 nm, due to the 4f 65d → 4f 7(8 S 7/2) transition. With increasing temperature, the full width at half maximum Γ(T) of the PL band of EuGa2S4 and EuGa2S4:Er3+ crystals increases from 0.15 to 0.22 and from 0.13 to 0.19 eV, respectively. Over the entire temperature range studied, Γ(T) is a linear function of T 1/2. The 545-nm emission intensity and Eu2+ excited state lifetime in EuGa2S4 and EuGa2S4:Er3+ vary exponentially with temperature. The luminescence quenching energies evaluated from the Arrhenius plots of I(103/T) and τ(103/T) coincide (0.10 eV) within the error of determination. 相似文献
4.
Devender Singh Vijeta Tanwar Anura P. Simantilleke Bernabe Mari Pratap Singh Kadyan Ishwar Singh 《Journal of Materials Science: Materials in Electronics》2016,27(3):2260-2266
BaAl2O4:Eu2+,RE3+ (RE3+=Y, Pr) down conversion nanophosphors were prepared at 600 °C by a rapid gel combustion technique in presence of air using boron as flux and urea as a fuel. A comparative study of the prepared materials was carried out with and without the addition of boric acid. The boric acid was playing the important role of flux and reducer simultaneously. The peaks available in the XPS spectra of BaAl2O4:Eu2+ at 1126.5 and 1154.8 eV was ascribed to Eu2+(3d 5/2) and Eu2+(3d 3/2) respectively which confirmed the presence of Eu2+ ion in the prepared lattice. Morphology of phosphors was characterized by tunneling electron microscopy. XRD patterns revealed a dominant phase characteristics of hexagonal BaAl2O4 compound and the presence of dopants having unrecognizable effects on basic crystal structure of BaAl2O4. The addition of boric acid showed a remarkable change in luminescence properties and crystal size of nanophosphors. The emission spectra of phosphors had a broad band with maximum at 490–495 nm due to electron transition from 4f 65d 1 → 4f 7 of Eu2+ ion. The codoping of the rare earth (RE3+=Y, Pr) ions help in the enhancement of their luminescent properties. The prepared phosphors had brilliant optoelectronic properties that can be properly used for solid state display device applications. 相似文献
5.
Yanxia Tang Yongfei Ye Haihui Liu Xiongfei Guo Hongxia Tang Wenzhong Yin Yaping Gao 《Journal of Materials Science: Materials in Electronics》2017,28(2):1301-1306
NaLa(WO4)2:Eu3+ phosphors with different Eu3+ concentrations have been synthesized by a hydrothermal method. The phase is confirmed by XRD analysis, which shows a pure-phase NaLa(WO4)2 XRD pattern for all of NaLa(WO4)2:Eu3+ phosphors. The SEM and TEM images indicate that all of NaLa(WO4)2:Eu3+ phosphors have a octahedral morphology. These suggest that the Eu3+ doping has no influence on the structure and growth of NaLa(WO4)4 particles. By monitoring the emission of Eu3+ at 615 nm, NaLa(WO4)2:Eu3+ phosphors show excitation bands originating from both host and Eu3+ ions. Under the excitation at 271 nm corresponding to WO4 2? groups, emission bands coming from the 1A1 → 3T1 transition with the WO4 2? groups and the 5D0 → 7Fj (j = 0, 1, 2, 3 and 4) transitions of Eu3+ are observed. The emission intensity relating to WO4 2? groups decreases with increasing Eu3+ concentration. But emission intensities of Eu3+ increase firstly and then decreases because of concentration quenching effect. Under the excitation at 395 nm corresponding to 7F0 → 5L6 transition of Eu3+, only characteristic Eu3+ emission bands can be observed. The results of this work suggest that tunable luminescence can be obtained for Eu3+ doped NaLa(WO4)2 phosphors by changing Eu3+ concentration and excitation wavelength. 相似文献
6.
Cong Zhao Yong Pu Shi-xiu Cao Xiao-long Jing Shan-yong Chen Ming-xing Ma Ling-ling Peng Ting Lu Da-chuan Zhu Dian-yong Tang 《Journal of Materials Science: Materials in Electronics》2018,29(16):13588-13595
Color rendering index and color temperature are the key factors for the LEDs application. The two points are closely related to the emission spectrum shape of phosphors. As the key factors for the LEDs application, both the above aspects are closely dependent on the emission spectrum shape of phosphors. In this study, the emission spectrum shape has been adjusted via a home designed route. A combination of structural, morphological, and optical characterization techniques has been used to study the shape evolution mechanism. The structural results show that the Sr2SiO4 phase has not been changed with the sintering temperature increasing, but the emission spectrum shape has changed dramatically, meanwhile, the colorimetric coordinate moves from blue-green to green region. Gaussian fitting method has been used to treat the emission spectrum, and the as-obtained results indicate the emission spectrum contains two single bands, which come from the 4f7(7S7/2)–4f6(7FJ)5d1 transition of Eu2+ on the different Sr sites in the Sr2SiO4 crystal. The intensity of the two single bands is driven by sintering temperature, because of the difference between the energy barrier of the Eu2+ occupying the different Sr sites in the matrix crystal. Moreover, the mechanism of the above phenomenon has also been studied by means of first principles method, and the obtained results agree well with the former deduction. 相似文献
7.
Pengfei Niu Xiaohua Liu Yiru Wang Weiren Zhao 《Journal of Materials Science: Materials in Electronics》2018,29(1):124-129
Ba2LaV3O11:Eu3+ phosphors were firstly synthesized by the traditional solid-state reaction method at 1100 °C. Their luminescence properties were investigated by photoluminescence excitation and emission spectra. The excitation spectrum shows a broad band centered at about 275 nm in the region from 200 to 370 nm, which is attributed to an overlap of the charge transfer transitions of O2??→?V5+ and O2??→?Eu3+. The phosphors exhibit the red emissions of Eu3+ and the emission intensity ratio of 5D0?→?7F2 to 5D0?→?7F1 is dependent on the Eu3+ concentration due to an environment change about Eu3+ ions. Concentration quenching occurs at 30 mol% in the phosphors and exchange interaction is its main mechanism. Ba2LaV3O11:Eu3+ displays tunable CIE color coordinates from yellow orange to red depended on Eu3+ content, which may have a potential application for illuminating and display devices. 相似文献
8.
S. Sailaja S. J. Dhoble Nameeta Brahme B. Sudhakar Reddy 《Journal of Materials Science》2011,46(24):7793-7798
A new series of Eu3+ ions-activated calcium gadolinium tungstate [Ca2Gd2W3O14] phosphors were synthesized by conventional solid-state reaction method. The X-ray diffraction patterns of the powder samples
indicate that the Eu3+: Ca2Gd2W3O14 phosphors are of tetragonal structure. The prepared phosphors were well characterized by scanning electron microscopy (SEM),
energy dispersive X-ray analysis (EDAX), Fourier transform infrared spectroscopy (FTIR), photoluminescence (PL), and mechanoluminescence
(ML) spectra. PL spectra of Eu3+: Ca2Gd2W3O14 powder phosphors have shown strong red emission at 615 nm (5D0 → 7F2) with an excitation wavelength λ
exci = 392 nm (7F0 → 5L6). The energy transfer from tungstate groups to europium ions has also reported. Mechanoluminescence studies of Eu3+: Ca2Gd2W3O14 phosphors have also been explained systematically. 相似文献
9.
A new efficient phosphor, Eu2+/Eu3+ and Ce3+ activated Na2Zn5(PO4)4 has been synthesized by solid-state reaction technique at high temperature. X-ray powder diffraction analysis confirmed the
formation of Na2Zn5(PO4)4 host lattice. Scanning electron microscopy indicated that the microstructure of the phosphor consisted of irregular fine
grains with a size of about 0·5–2 μm. Photoluminescence excitation spectrum measurements of Ce3+ activated Na2Zn5(PO4)4 show that the phosphor can be efficiently excited by UV-Vis light from 280 to 310 nm to realize emission in the visible (blue)
range due to the 5d-4f transition of Ce3+ ions which is applicable for scintillation purpose, whereas Eu2+/Eu3+ activated Na2Zn5(PO4)4 phosphor emits blue, green and red emission spectrum shows at 487 nm, 546 nm with a dominant peak at 611 nm respectively,
due to Eu2+/Eu3+ ions which is promising candidate for solid state lighting. Therefore, newly synthesised, by low cost and easy technique
prepared, novel phosphors may be useful as RGB phosphor for solid state lighting application. 相似文献
10.
Mingxia Zhao Zhiju Zhao Lixia Yu Liqin Yang Junbing Jiang Xuan Li Guanghua Li 《Journal of Materials Science: Materials in Electronics》2018,29(3):1832-1836
A series of Sr3La(PO4)3:Eu2+/Mn2+ phosphors were synthesized by a solid state reaction. The phase and the optical properties of the synthesized phosphors were investigated. The XRD results indicate that the doped Eu2+ and Mn2+ ions do not change the phase of Sr3La(PO4)3. The peak wavelengths of Eu2+ single doped and Eu2+/Mn2+ codoped Sr3La(PO4)3 phosphors shift to longer wavelength due to the larger crystal field splitting for Eu2+ and Mn2+. The increases of crystal field splitting for Eu2+ and Mn2+ are induced by the substitution of Sr2+ by Eu2+ and Mn2+ in Sr3La(PO4)3 host. Due to energy transfer from Eu2+ to Mn2+ in Sr3La(PO4)3:Eu2+/Mn2+ phosphors, tunable luminescence was obtained by changing the concentration of Mn2+. And the white light was emitted by Sr3La(PO4)3:3.0 mol%Eu2+/4.0 mol%Mn2+ and Sr3La(PO4)3:3.0 mol%Eu2+/5.0 mol%Mn2+ phosphors. 相似文献
11.
Xingdong Lü Wangen Shu Qin Fang Quanmao Yu Xinqiang Xiong 《Journal of Materials Science》2007,42(15):6240-6245
The polycrystalline Eu2+ and RE3+ co-doped strontium aluminates SrAl2O4:Eu2+, RE3+ were prepared by solid state reactions. The UV-excited photoluminescence, persistent luminescence and thermo-luminescence
of the SrAl2O4:Eu2+, RE3+ phosphors with different composition and doping ions were studied and compared. The results showed that the doped Eu2+ ion in SrAl2O4:Eu2+, Dy3+ phosphors works as not only the UV-excited luminescent center but also the persistent luminescent center. The doped Dy3+ ion can hardly yield any luminescence under UV-excitation, but can form a electron trap with appropriate depth and greatly
enhance the persistent luminescence and thermo-luminescence of SrAl2O4:Eu2+. Different co-doping RE3+ ions showed different effects on persistent luminescence. Only the RE3+ ion (e.g. Dy3+, Nd3+), which has a suitable optical electro-negativity, can form the appropriate electron trap and greatly improve the persistent
luminescence of SrAl2O4:Eu2+. Based on above observations, a persistent luminescence mechanism, electron transfer model, was proposed and illustrated. 相似文献
12.
Xiao Chun Zhou Lu Ping Zhong Qiu Ping Liu Ren Yun Kuang Hong Mei Chen 《Inorganic Materials》2009,45(11):1295-1298
New red emitting phosphors, Ca3(VO4)2:Eu3+,Bi3+, Ca3((P,V)O4)2:Eu3+ were synthesized by low temperature solid-state reaction and characterized by X-ray diffraction, scanning electron microscopy, photoluminescence spectra and Fourier transform infrared spectroscopy. The results show that the red emission located at about 613 nm was ascribed to 5 D 0-7 F 2 transition of Eu3+. The effect of by Bi doping and by P doping was also investigated systematically. 相似文献
13.
Xiaochun Zhou Xiaojun Wang Renyun Kuang Jin Guo Hongmei Chen 《Inorganic Materials》2010,46(11):1244-1247
Different crystalline Ca3(VO4)2 nanocrystals have been synthesized successfully via a facile low temperature method with lithium addition. After different
ration of Li+ doping into the Ca3(VO4)2: Eu3+ host, the crystallinity of the sample becomes different, resulting in different of luminescence intensity of the characteristic
emission of Eu3+ ions. This approach provides economically viable route for large-scale synthesis of this kind of nanomaterials. 相似文献
14.
The novel Ca4?x(PO4)2O: xDy3+ and Ca4?x?y(PO4)2O: xDy3+, yEu2+ multi-color phosphors were synthesized by traditional solid-state reaction. The crystal structure, particle morphology, photoluminescence properties and energy transfer process were investigated in detail. The X-ray diffraction (XRD) results demonstrate that the products showed pure monoclinic phase of Ca4(PO4)2O when x < 0.1. The scanning electron microscopy (SEM) indicated that the phosphors were grain-like morphologies with diameters of ~ 3.7–7.0 μm. Under excitation of 345 nm, Dy3+-doped Ca4(PO4)2O phosphors showed multi-color emission bands at 410, 481 and 580 nm originated from oxygen vacancies and Dy3+. Interestingly, Ca4(PO4)2O: Dy3+, Eu2+ phosphors exhibited blue emission band at 481 nm and broad emission band from 530 to 670 nm covering green to red regions. The energy transfer process from Dy3+ to Eu2+ was observed for the co-doped samples, and the energy transfer efficiency reached to 60% when Eu2+ molar concentration was 8%. In particular, warm/cool/day white light with adjustable CCT (2800–6700 K) and high CRI (Ra > 85) can be obtained by changing the Eu2+ co-doping contents in Ca4(PO4)2O: Dy3+, Eu2+ phosphors. The optimized Ca3.952(PO4)2O: 0.04Dy3+, 0.008Eu2+ phosphor can achieve the typical white light with CCT of 4735 K and CRI of 87. 相似文献
15.
V. V. Yagodin A. V. Ishchenko M. N. Sarychev G. F. Babailova N. S. Akhmadullina A. S. Lysenkov Yu. F. Kargin B. V. Shul’gin 《Inorganic Materials》2018,54(5):446-453
Polycrystalline Al5O6N samples have been prepared by sol–gel synthesis followed by carbothermal reduction and nitridation. X-ray luminescence (XRL) spectra and thermoluminescence (TL) curves of Ce3+- and Eu2+-doped aluminum oxynitride have been measured in the temperature range 5–380 K and analyzed. Working TL peaks have been detected in the range 150–250 K for the Al5O6N:Ce3+ sample and in the range 140–200 K for the Al5O6N:Eu2+ samples. There are also lower temperature peaks: in the ranges 10–60 and 20–100 K. The XRL spectra of the samples have been measured at temperatures of 8 (for the first time) and 300 K. 相似文献
16.
A. N. Georgobiani B. G. Tagiev O. B. Tagiev T. G. Kerimova S. A. Abushov S. G. Asadullaeva 《Inorganic Materials》2010,46(2):116-119
The current (electrical transport) through In/ZnGa2Se4/In structures has been measured as a function of temperature and applied electric field at temperatures from 77 to 400 K in fields from 10 to 3 × 104 V/cm. The results are analyzed in terms of the Poole-Frenkel effect and space-charge-limited currents. The activation energy of traps and trap concentration in ZnGa2Se4 and its refractive index are determined to be E t= 0.8 eV, N t = 4 × 1013 cm?3, and n = 2.4, respectively. 相似文献
17.
Xiang-Hong He Ming-Yun Guan Jian-Hua Sun Ning Lian Tong-Ming Shang 《Journal of Materials Science》2010,45(1):118-123
LiEu1−x
(W2−y
Mo
y
)O8:xBi3+ series red-emitting phosphors were synthesized by solid state reaction. The structure, morphology, and photoluminescent properties
of phosphors were studied by X-ray powder diffraction, scanning electron microscopy, and photoluminescence spectrum, respectively.
X-ray powder diffraction analysis showed that the as-obtained phosphors belong to the scheelite structure. The average particle
size of the investigated phosphor was about 8 μm. The excitation spectrum exhibits a charge-transfer broad band along with
some sharp peaks from the typical 4f–4f transitions of Eu3+. Under excitation of UV, near-UV, or blue light, these phosphors showed strong red emission at 615 nm due to 5D0–7F2 transition of Eu3+. The incorporation of Mo6+ into LiEuW2O8:Bi3+ could induce red-shift of the charge-transfer broad band and a remarkable increase of photoluminescence. The highest red-emission
intensity was observed with LiEu0.80Mo2O8:0.20Bi3+. Compared with the commercial red-emitting phosphor, Y2O2S:Eu3+, the emission intensity of LiEu0.80Mo2O8:0.20Bi3+ phosphor is much stronger than that of Y2O2S:Eu3+ and its chromaticity coordinates are closer to the standard values than that of the commercial phosphor. The optical properties
of LiEu0.80Mo2O8:0.20Bi3+ phosphor make it attractive for the application in white-light-emitting diodes (LEDs), in particular for near-UV InGaN-based
white-LEDs. 相似文献
18.
M. M. Kolte V. B. Pawade S. J. Dhoble 《Journal of Materials Science: Materials in Electronics》2018,29(2):906-913
This article present the reports on optical study of Eu2+ and Ce3+ doped SrMg2Al6Si9O30 phosphors, which has been synthesized by combustion method at 550 °C. Here SrMg2Al6Si9O30:Eu2+ emission band observed at 425 nm by keeping the excitation wavelength constant at 342 nm, whereas SrMg2Al6Si9O30:Ce3+ ions shows the broad emission band at 383 nm, under 321 nm excitation wavelength, both the emission bands are assigned due to 5d–4f transition respectively. Further, phase purity, morphology and crystallite size are confirmed by XRD, SEM and TEM analysis. However, the TGA analysis is carried out to know the amount of weight lost during the thermal processing. The CIE coordinates of SrMg2Al6Si9O30:Eu2+ phosphor is observed at x?=?0.160, y?=?0.102 respectively, which may be used as a blue component for NUV-WLEDs. The critical distance of energy transfer between Ce3+ ions and host lattice is found to be 10.65 Å. 相似文献
19.
E. V. Tret’yak G. P. Shevchenko T. A. Solomakha M. V. Korzhik 《Inorganic Materials》2017,53(3):307-312
BaI2:Eu2+,Eu3+ powders have been prepared by heat-treating BaCO3:Eu3+ precursor powders of various morphologies in an iodinating agent atmosphere and their structural properties, morphology, optical absorption, and luminescence have been studied. The results demonstrate that the powders thus prepared consist of a mixture of crystalline hydrates of various compositions, dominated by BaI2 ? 2Н2О (sp. gr. C2/c), and that the Eu2+: Eu3+ ratio in the powders is determined by the morphology of the precursor. 相似文献
20.
K. A. Gedekar S. P. Wankhede S. V. Moharil R. M. Belekar 《Journal of Materials Science: Materials in Electronics》2018,29(6):4466-4477
Compound CaAl4O7 (CA4), SrAl4O7 (SA4), CaAl12O19 (CA12) and SrAl12O19 (SA12) have been synthesized by using single step combustion method. The phosphors have been characterized by XRD, SEM and PL techniques. Both CA4 and SA4 possess monoclinic crystal structure whereas CA12 and SA12 possess hexagonal structure. Effects of crystal symmetry on the emission spectrum have been studied by doping the samples with Ce3+ and Eu2+ ions. The luminescence properties of Ce3+ and Eu2+ in these hosts is discussed on the basis of their covalent character and the crystal field splitting of the d-orbital of dopant ions. The spectroscopic properties, crystal field splitting, centroid shift, red shift and stokes shift have been studied. Spectroscopic properties of Eu2+ ions have been accurately predicted from those of Ce3+ ions in the same host. Most importantly experimental results were matched excellently with the calculated results. The preferential substitution of Ce3+ and Eu2+ at different Ca2+, Sr2+ crystallographic sites have been discussed. The dependence of emission wavelengths of Ce3+ and Eu2+ on the local symmetry of different crystallographic sites was also studied by using Van Uitert’s empirical relation. Differences in the emission spectrum of these samples have been observed despite their similar crystal structures and space group. Possible reasons have been discussed. 相似文献