共查询到20条相似文献,搜索用时 0 毫秒
1.
V. Ilcheva P. Petkov V. Boev F. Sima C.N. Mihailescu C. Popov 《Applied Surface Science》2009,255(24):9691-9694
Thin (AsSe)100−xAgx films have been grown onto quartz substrates by vacuum thermal evaporation or pulsed laser deposition from the corresponding bulk materials. The amorphous character of the coatings was confirmed by X-ray diffraction investigations. Their transmission was measured within the wavelength range 400-2500 nm and the obtained spectra were analyzed by the Swanepoel method to derive the optical band gap Eg and the refractive index n. We found that both parameters are strongly influenced by the addition of silver to the glassy matrix: Eg decreases while n increases with Ag content. These variations are discussed in terms of the changes in the atomic and electronic structure of the materials as a result of silver incorporation. 相似文献
2.
Vacuum ultraviolet (VUV) excitation and photoluminescence (PL) characteristics of Eu3+ ion doped borate phosphors; BaZr(BO3)2:Eu3+ and SrAl2B2O7:Eu3+ are studied. The excitation spectra show strong absorption in the VUV region with the absorption band edge at ca. 200 nm for BaZr(BO3)2:Eu3+ and 183 nm for SrAl2B2O7:Eu3+, respectively, which ensures the efficient absorption of the Xe plasma emission lines. In BaZr(BO3)2:Eu3+, the charge transfer band of Eu3+ does not appear strongly in the excitation spectrum, which can be enhanced by co-doping Al3+ ion into the BaZr(BO3)2 lattices. The luminescence intensity of BaZr(BO3)2:Eu3+ is also increased by Al3+ incorporation into the lattices. The PL spectra show the strongest emission at 615 nm corresponding to the electric dipole 5D0→7F2 transition of Eu3+ in both BaZr(BO3)2 and SrAl2B2O7, similar to that in YAl3(BO3)4, which results in a good color purity for display applications. 相似文献
3.
This paper reports on the absorption, visible and near-infrared luminescence properties of Nd3+, Er3+, Er3+/2Yb3+, and Tm3+ doped oxyfluoride aluminosilicate glasses. From the measured absorption spectra, Judd-Ofelt (J-O) intensity parameters (Ω2, Ω4 and Ω6) have been calculated for all the studied ions. Decay lifetime curves were measured for the visible emissions of Er3+ (558 nm, green), and Tm3+ (650 and 795 nm), respectively. The near infrared emission spectrum of Nd3+ doped glass has shown full width at half maximum (FWHM) around 45 nm (for the 4F3/2→4I9/2 transition), 45 nm (for the 4F3/2→4I11/2 transition), and 60 nm (for the 4F3/2→4I13/2 transition), respectively, with 800 nm laser diode (LD) excitation. For Er3+, and Er3+/2Yb3+ co-doped glasses, the characteristic near infrared emission bands were spectrally centered at 1532 and 1544 nm, respectively, with 980 nm laser diode excitation, exhibiting full width at half maximum around 50 and 90 nm for the erbium 4I13/2→4I15/2 transition. The measured maximum decay times of 4I13/2→4I15/2 transition (at wavelength 1532 and 1544 nm) are about 5.280 and 5.719 ms for 1Er3+ and 1Er3+/2Yb3+ (mol%) co-doped glasses, respectively. The maximum stimulated emission cross sections for 4I13/2→4I15/2 transition of Er3+ and Er3+/Yb3+ are 10.81×10−21 and 5.723×10-21 cm2. These glasses with better thermal stability, bright visible emissions and broad near-infrared emissions should have potential applications in broadly tunable laser sources, interesting optical luminescent materials and broadband optical amplification at low-loss telecommunication windows. 相似文献
4.
Marcin Sobczyk 《Journal of luminescence》2009,129(5):430-418
In an attempt to find a neodymium-vanadate system with long lifetime of 4F3/2 level and relatively strong 4F3/2→4I11/2 emission for laser applications, the optical properties of Nd3+ in a new KZnLa(VO4)2 host is reported. The crystalline samples were obtained at 900 °C in air. The samples were crystallized in monoclinic system and were isostructural with KZnLa(PO4)2. KZnLa0.99Nd0.01(VO4)2 strongly emits in the near infrared range with the maxima at 871.6 and 1057 nm upon excitation through the 4F5/2 level (808 nm) or by the charge transfer bands of VO43−. The lifetime of 4F3/2 level of Nd3+ ion is larger than that observed in other neodymium-vanadates systems. 相似文献
5.
Honghua Huang 《Solid State Communications》2004,132(11):773-777
Y2SiO5 doped with Eu3+ were in situ synthesized by a hybrid precursor assembly sol-gel technology employing four different silicate sources, 3-aminopropyl-trimethoxysilane (APMS), 3-aminopropyl-triethoxysilane (APES), 3-aminopropyl-methyl-diethoxysilane (APMES) and tetraethoxysilane (TEOS), respectively. The SEM result shows that there exist some novel unexpected morphological microrod structures owing to using the crosslinking reagents other than TEOS as silicate source. The photoluminescent properties of Y2SiO5:Eu3+ have been studied as a function of Eu3+ doping concentration. A cross-relaxation process between identical Eu3+ ions results in the quenching of the 5D1 emission for high concentration sample. 相似文献
6.
In this paper, we present the photoluminescence properties of Pr3+-, Sm3+- and Dy3+-doped germanate glasses and glass ceramics. From the X-ray diffraction measurement, the host glass structure was determined. These glasses have shown strong absorption bands in the near-infrared (NIR) region. Compared to Pr3+-, Sm3+- and Dy3+-doped glasses, their respective glass ceramics have shown stronger emissions due to the Ba2TiGe2O8 crystalline phase. For Pr3+-doped glass and glass ceramic, emission bands centered at 530 nm (3P0→3H5), 614 nm (3P0→3H6), 647 nm (3P0→3F2) and 686 nm (3P0→3F3) have been observed with 485 nm (3H4→3P0) excitation wavelength. Of them, 647 nm (3P0→3F2) has shown bright red emission. Emission bands of 4G5/2→6H5/2 (565 nm), 4G5/2→6H7/2 (602 nm) and 4G5/2→6H9/2 (648 nm) for the Sm3+:glass and glass ceramic, with excitation at 6H5/2→4F7/2 (405 nm) have been recorded. Of them, 4G5/2→6H7/2 (602 nm) has shown a bright orange emission. With regard to the Dy3+:glass and glass ceramic, a bright fluorescent yellow emission at 577 nm (4F9/2→6H13/2) has been observed, apart from 4F9/2→6H11/2 (667 nm) emission transition with an excitation at 454 nm (6H15/2→4I15/2) wavelength. The stimulated emission cross-sections of all the emission bands of Pr3+, Sm3+ and Dy3+:glasses and glass ceramics have been computed based on their measured full-width at half-maxima (FWHM, Δλ) and lifetimes (τm). 相似文献
7.
Yujin Chen 《Solid State Communications》2004,132(8):533-538
Yb3+-doped La2(WO4)3 single crystals were grown by the Czochralski technique. Absorption and fluorescence spectra of the crystal were recorded at the room temperature. The stimulated emission cross-sections of Yb3+ ions were calculated using the reciprocity method and Fuchtbauer-Ladenburg formula, respectively. The fluorescence decay curves of 2F5/2 manifold of Yb3+ ions were recorded at room temperature for both crystal and powder samples. The effect of radiation trapping on the spectroscopic properties is discussed. Comparison with other Yb3+-doped laser crystals is made. The results show that Yb3+:La2(WO4)3 crystal is a promising laser material. 相似文献
8.
We have determined the photophysical properties of [Eu(C12H8N2)2](NO3)3, (EuPhen), a complex which is very promising for photonic and optoelectronic applications, because of its easy synthetic procedure and high thermal stability (up to 300 °C) combined with large sensitization efficiency and good emission quantum yield. Available experimental absorption and emission data have been analyzed by using Judd-Ofelt analysis. Moreover, semi-empirical calculations have been used to determine the structure of the complex and to interpret the convoluted shape of the absorption spectrum. 相似文献
9.
Kyoo Sung Shim Ye Ran Jeong Byung Chun Choi Jong Seong Bae Jung Hwan Kim 《Applied Surface Science》2007,253(19):8146-8150
Li-doping has been used to improve luminescent characteristics of thin films. Influence of Li-doping on the crystallization, surface morphology and luminescent properties of GdVO4:Eu3+ films have been investigated. Crystallinity and surface morphology of thin films have been very important factors to determine luminescent characteristics and depended on the deposition conditions. The GdVO4:Eu3+ and Li-doped GdVO4:Eu3+ thin films have been grown using pulsed laser deposition method on Al2O3 (0 0 0 1) substrates at a substrate temperature of 600 °C under an oxygen pressure of 13.33-53.33 Pa. The crystallinity and surface morphology of the films were investigated using X-ray diffraction (XRD) and atomic force microscope (AFM), respectively. A broadband incoherent ultraviolet light source with a dominant excitation wavelength of 310 nm and a luminescence spectrometer have been used to measure photoluminescence spectra at room temperature. The emitted radiation was dominated by the red emission peak at 619 nm radiated from the transition of 5D0-7F2 of Eu3+ ions. Particularly, the peak intensity of Li-doped GdVO4 films was increased by a factor of 1.7 in comparison with that of GdVO4:Eu3+ films. The enhanced luminescence results not only from the improved crystallinity but also from the reduced internal reflections caused by rougher surfaces. The luminescent intensity and surface roughness exhibited similar behavior as a function of oxygen pressure. 相似文献
10.
Honghua Huang 《Applied Surface Science》2006,252(8):2967-2972
Zn2SiO4 doped with Tb3+ were in situ synthesized by a modified sol-gel technology with the assembly hybrid precursor employed four different silicate sources, i.e. 3-aminopropyl-trimethoxysilane (APMS), 3-aminopropyl-triethoxysilane (APES), 3-aminopropyl-methyl-diethoxysilane (APMES) and tetraethoxysilane (TEOS), respectively. The SEM result shows that there exist some novel unexpected micromorphological structures of hexagon-like with the dimension of 0.5-1.0 μm. The photoluminescent properties of Zn2SiO4:Tb3+ phosphors have been studied as a function of Tb3+ doping concentration. Cross-relaxation process between identical Tb3+ ions results in the quenching of the 5D3 emission for high concentration sample. 相似文献
11.
Qiyue Shao 《Journal of luminescence》2009,129(8):879-475
Sodium europium double tungstate [NaEu(WO4)2] phosphor was prepared by the solid-state reaction method. Its crystal structure, photoluminescence properties and thermal quenching characteristics were investigated aiming at the potential application in the field of white light-emitting diodes (LEDs). The influences of Sm doping on the photoluminescence properties of this phosphor were also studied. It is found that this phosphor can be effectively excited by 394 or 464 nm light, which nicely match the output wavelengths of near-ultraviolet (UV) or blue LED chips. Under 394 or 464 nm light excitation, this phosphor exhibits stronger emission intensity than the Y2O2S:Eu3+ or Eu2+-activated sulfide phosphor. The introduction of Sm3+ ions can broaden the excitation peaks at 394 and 464 nm of the NaEu(WO4)2 phosphor and significantly enhance its relative luminance under 400 and 460 nm LEDs excitation. Furthermore, the relative luminance of NaEu(WO4)2 phosphor shows a superior thermal stability compared with the commercially used sulfide or oxysulfide phosphor, and make it a promising red phosphor for solid-state lighting devices based on near-UV or blue LED chips. 相似文献
12.
A series of Er3+/Yb3+-co-doped 60Bi2O3-(40−x) B2O3 -xGa2O3 (BBGA x=0, 4, 8, 12, 16 mol%) glasses have been prepared. The absorption spectra, emission spectra, fluorescence lifetime of Er3+:4I13/2 level and thermal stability were measured and investigated. Three Judd-Ofelt intensity parameters Ωt (t=2,4,6) (Ω2=(4.67-5.93)×10−20 cm2, Ω4=(1.50-1.81)×10−20 cm2, Ω6=(0.92-1.17)×10−20 cm2) of Er3+ ions were calculated by Judd-Ofelt theory. It is found that the Ω6 first increases with the increase of Ga2O3 content from 0 to 8 mol% and then decreases, which is mainly affected by the number of non-bridging oxygen ions of the glass network. The high peak of stimulated emission cross-section () of Er3+: 4I13/2→4I15/2 transition were obtained according to McCumber theory and broad full width at half maximum (FWHM=69-76 nm) of the 4I13/2→4I15/2 transition of Er3+ ions were measured. The results indicate that these new BBGA glasses can be used as a candidate host material for potential broadband optical amplifiers. 相似文献
13.
Qing Yang Sotaro Izumi Atsushi Tackeuchi Hirokazu Tatsuoka 《Applied Surface Science》2010,256(22):6928-6931
ZnO/ZnGa2O4 composite layers were synthesized by simple thermal oxidation of ZnS substrates with gallium in the air. The continuous-wave and time-resolved photoluminescence measurements for the composites were performed at room temperature. It is found that the visible deep level emission from ZnO in ZnO/ZnGa2O4 composite layer was almost suppressed. In addition, the UV emission with long lifetime was also observed in comparison with that of pure ZnO layer without ZnGa2O4. 相似文献
14.
Potential PDP phosphors with strong absorption around 172 nm: Rare earth doped NaLaP2O7 and NaGdP2O7
Jun Lin Yuan Jiao Wang Ding Bang Xiong Jing Tai Zhao Yi Bing Fu Chao Shu Shi 《Journal of luminescence》2007,126(2):717-722
NaLaP2O7 and NaGdP2O7 powder samples are prepared by solid-state reactions at 750 and 600 °C, respectively, and the VUV-excited luminescence properties of Ln3+ (Ln=Ce, Pr, Tb, Tm, Eu) in both diphosphates are studied. Ln3+ ions in both hosts show analogous luminescence. For Ce3+-doped samples, the five Ce3+ 5d levels can be clearly identified. As for Pr3+ and Tb3+-doped samples, strong 4f-5d absorption band around 172 nm is observed, which matches well with Xe-He excimer in plasma display panel (PDP) devices. As a result, Pr3+ can be utilized as sensitizer to absorb 172 nm VUV photon and transfer energy to appropriate activators, and Tb3+-doped NaREP2O7(RE=La, Gd) are potential 172 nm excited green PDP phosphors. For Tm3+ and Eu3+-doped samples, the Tm3+-O2− charge transfer band (CTB) is observed to be at 177 nm, but the CTB of Eu3+ is observed at abnormally low energy position, which might originate from multi-position of Eu3+ ions. The similarity in luminescence properties of Ln3+ in both hosts indicates certain structural resemblance of coordination environment of Ln3+ in the two sodium rare earth diphosphates. 相似文献
15.
The polarized absorption spectra, infrared fluorescence spectra, upconversion visible fluorescence spectra, and fluorescence decay curve of orientated Nd3+:KGd(WO4)2 crystal were measured at room-temperature. Some important spectroscopic parameters were investigated in detail in the framework of the Judd-Ofelt theory and the Fuchtbauer-Ladenburg formula. The effect of the crystal structure on the spectroscopic properties of the Nd3+ ions was analyzed. The relation among the spectroscopic parameters and the laser performances of the Nd3+:KGd(WO4)2 crystal was discussed. 相似文献
16.
In this paper, the Czochralski growth, absorption spectra, and photoluminescence spectra of Nd:GdVO4 crystals are studied. From its absorption spectra, Nd:GdVO4 is found to exhibit an anisotropic optical absorption effect, and its effective Judd-Ofelt parameters are calculated: Ω2=10.281×10−20 cm2, Ω4=5.426×10−20 cm2 and Ω6=9.943×10−20 cm2. By these parameters, the absorption oscillator strengths, emission oscillator strengths, transition probabilities, fluorescence branch ratios, energy lifetimes, and integrated emission cross-sections are also derived. The photoluminescence spectra of Nd:GdVO4 crystal consist of a wide emission band of host and the characteristic emission bands of Nd3+. Based on the excitation spectrum, both the two evident peaks locating at 345 and 371 nm are ascribed to the characteristic excitation of Nd3+, and an energy transfer from the host to its doping Nd3+ ions is indicated. 相似文献
17.
Lei Zhou 《Applied Surface Science》2008,254(6):1847-1851
Y2−xTbxSiO5 and Y2−xEuxSiO5 nanophosphors with seven different kinds of silicate sources were synthesized by sol-gel method. The structures have been investigated to be composed of nanometer-size grains of 30-60 nm through X-ray diffraction (XRD) and scanning electron microscopy (SEM) was used to compare the different morphology of patterns from seven different silicon sources. The photoluminescence of Y2−xTbxSiO5 was investigated as a function of silicate sources and the results revealed that these nanometer materials showed the characteristic emission 5D4 → 7FJ (J = 6, 5, 4, 3) of Tb ions. The characteristic emission 5D0 → 7FJ (J = 1, 2, 4) of Eu ions was also found in the materials of Y2−xEuxSiO5. 相似文献
18.
Zuoling Fu 《Journal of luminescence》2009,129(12):1669-359
In this paper, the Ca2SnO4:Eu3+ phosphor was prepared by low-temperature sol-gel method. The influence of calcined temperature and time on structure of Ca2SnO4:Eu3+ was investigated by using X-ray powder diffraction (XRD). The experimental results show that the dried gel was crystallized to the pure orthorhombic phase after calcination at 900 °C in air for 6 h. These phosphors have displayed bright red color under a UV source. The richness of the red color has been verified by determining their color coordination from the CIE standard charts, and this red emission has been assigned to 5D0→7F2 electric dipole transition at 616 and 620 nm. The excellent luminescence properties make it possible as a good candidate for plasma display panel (PDP) application. 相似文献
19.
Lingli Wang 《Journal of luminescence》2007,126(1):160-164
The luminescent properties of CaYBO4:Ln(Ln=Eu3+, Tb3+) were investigated under ultraviolet (UV) and vacuum ultraviolet (VUV) region. The CT band of Eu3+ at about 245 nm blue-shifted to 230 nm in VUV excitation spectrum; the band with the maximum at 183 nm was considered as the host lattice absorption. For the sample of CaYBO4:0.08Tb3+, the bands at about 235 and 263 nm were assigned to the f-d transitions of Tb3+ and the CT band of Tb3+ was calculated according to Jφrgensen's theory. Under UV and VUV excitation, the main emission of Eu3+ corresponding to the 5D0-7F2 transition located at about 610 nm and two intense emission of Tb3+ from the 5D4-7F5 transition had been observed at about 542 and 552 nm, respectively. With the incorporation of Gd3+ into the host lattice of CaYBO4, the luminescence of Tb3+ was enhanced while that of Eu3+ was decreased because of their different excitation mechanism. 相似文献
20.
The Tm3+/Er3+:NaGd(MoO4)2 crystal with dimensions of Φ22×30 mm3 was grown by Czochralski method. Polarized spectra and fluorescence lifetime for the 4I13/2(Er3+)→4I15/2(Er3+) transition at room temperature were investigated. Based on the Judd-Ofelt theory, the spontaneous transition probabilities, the fluorescent branching ratios and the radiative lifetimes were calculated. The fluorescence lifetime was measured to be 1.81 ms. The detailed excited-transition mechanism with 800 nm radiation is also discussed. 相似文献