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1.
Gd 2O 3:Eu 3+ and Li-doped Gd 2O 3:Eu 3+ luminescent thin films have been grown on Si(100) substrates using pulsed laser deposition. The films grown at different deposition conditions show different crystalline and morphology structures and luminescent characteristics. Although both cubic and monoclinic crystalline structures were observed in both Gd 2O 3:Eu 3+ and Li-doped Gd 2O 3:Eu 3+ films, the cubic structure becomes more dominant for Li-doped Gd 2O 3:Eu 3+ films. The photoluminescence brightness data obtained from Li-doped Gd 2O 3:Eu 3+ films indicate that Si(100) is a promising substrate for growth of high-quality Li-doped Gd 2O 3:Eu 3+ thin-film red phosphor. In particular, the incorporation of Li + ions into the Gd 2O 3 lattice induced a change of crystallinity and enhanced surface roughness. Two major factors to determine photoluminescence brightness for Li-doped Gd 2O 3:Eu 3+ films were crystalline phase and surface roughness. The highest emission intensity was observed with Gd 1.84Li 0.08Eu 0.08O 3, whose brightness was a factor of 2.1 larger than that of Gd 2O 3:Eu 3+ films. This phosphor is promising for applications in flat-panel displays. PACS 78.20.-e; 78.55.-m; 78.66.-w 相似文献
2.
Y 2-xGd xO 3:Eu 3+ luminescent thin films have been grown on Al 2O 3(0001) substrates using pulsed laser deposition. Films grown under different deposition conditions have been characterized using microstructural and luminescence measurements. The crystallinity, surface morphology and photoluminescence (PL) of the films are highly dependent on the amount of Gd present. The photoluminescence (PL) brightness data obtained from Y 2-xGd xO 3:Eu 3+ films grown under optimized conditions have indicated that Al 2O 3(0001) is one of the most promising substrates for the growth of high-quality Y 2-xGd xO 3:Eu 3+ thin-film red phosphors. In particular, the incorporation of Gd into the Y 2O 3 lattice could induce a remarkable increase of PL. The highest emission intensity was observed with Y 1.35Gd 0.60Eu 0.05O 3, whose brightness was increased by a factor of 3.1 in comparison with that of Y 2O 3:Eu 3+ films. This phosphor may be promising for application in flat-panel displays. PACS 78.20.-e; 78.55.-m; 78.66.-w 相似文献
3.
Gd-substituted Y 1-xGd xVO 4:Eu 3+ luminescent thin films have been grown on Al 2O 3(0001) substrates using pulsed-laser deposition. The films grown under different deposition conditions have been characterized
using microstructural and luminescent measurements. The crystallinity, surface morphology, and photoluminescence (PL) of the
films are highly dependent on the amount of Gd. The photoluminescence (PL) brightness data obtained from Y 1-xGd xVO 4:Eu 3+ films grown under optimized conditions have indicated that the PL brightness is more dependent on the surface roughness than
the crystallinity of the films. In particular, the incorporation of Gd into the YVO 4 lattice could induce a remarkable increase of PL. The highest emission intensity was observed with Y 0.57Gd 0.40Eu 0.03VO 4 thin film whose brightness was increased by a factor of 2.5 and 1.9 in comparison with that of YVO 4:Eu 3+ and GdVO 4:Eu 3+ films, respectively. This phosphor have application to flat panel displays.
PACS 78.20.-e; 78.55.-m; 78.66.-w 相似文献
4.
The influence of lithium doping on the crystallization, the surface morphology, and the luminescent properties of pulsed laser deposited Y 2−xGd xO 3:Eu 3+ thin film phosphors was investigated. The crystallinity, the surface morphology, and the photoluminescence (PL) of films depended highly on the Li-doping and the Gd content. The relationship between the crystalline and morphological structures and the luminescent properties was studied, and Li + doping was found to effectively enhance not only the crystallinity but also the luminescent brightness of Y 2−xGd xO 3:Eu 3+ thin films. In particular, the incorporation of Li and Gd into the Y 2O 3 lattice could induce remarkable increase in the PL. The highest emission intensity was observed Li-doped Y 1.35Gd 0.6O 3:Eu 3+ thin films whose brightness was increased by a factor of 4.6 in comparison with that of Li-doped Y 2O 3:Eu 3+ thin films. 相似文献
5.
Eu 3+-doped yttrium oxide (Eu:Y 2O 3) films were grown on fused-silica substrates by laser ablation. Depending on oxygen pressure, substrate temperature and laser energy density, the crystalline structure of the films, determined by X-ray diffraction and Raman spectroscopy, changes from monoclinic to cubic. The crystalline structure of the films is confirmed by Eu 3+ fluorescence spectra and refractive indices, measured by m-line spectroscopy. The cubic crystalline films show low-loss waveguiding properties. PACS 81.15.Fg; 78.55.Hx; 78.20.Ci 相似文献
6.
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 GdVO 4:Eu 3+ 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 GdVO 4:Eu 3+ and Li-doped GdVO 4:Eu 3+ thin films have been grown using pulsed laser deposition method on Al 2O 3 (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 5D 0- 7F 2 of Eu 3+ ions. Particularly, the peak intensity of Li-doped GdVO 4 films was increased by a factor of 1.7 in comparison with that of GdVO 4:Eu 3+ 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
7.
Eu 3+-doped lutetium oxide (Eu:Lu 2O 3) nanocrystalline films were grown on fused-silica substrates by pulsed laser deposition. Depending on deposition conditions (oxygen pressure, temperature and laser energy), the structure of the films changed from amorphous to crystalline and the cubic or monoclinic phases were obtained with varying preferential orientation and crystallite size. The monoclinic phase could be prepared for the first time at temperatures as low as 240 °C and in a narrow range of parameters. Although this phase has been previously reported for powder samples, it occurs only for high pressures and high temperatures preparation conditions. The refractive indices were measured by m-lines spectroscopy for both crystalline phases and their dispersion curve fitted by the Sellmeier expression. The specific Eu 3+ fluorescence properties of the different phases, monoclinic and cubic, were registered and show modifications due to the disorder induced by the nanometric size of the crystallites, emphasised in particular by quasi-selective excitation in the charge transfer band. 相似文献
8.
利用共沉淀法制备了纳米晶Gd 2O 3 : Eu 3+发光粉体。 在不同掺杂浓度、不同煅烧温度的系列样品中,均观测到Eu 3+离子的特征发射。样品的晶相与发射性质的研究表明:所制备的样品经800~1 300 ℃热处理后,晶相为立方相,1 400 ℃时开始向单斜相转变。荧光强度与Eu 3+离子掺杂浓度关系研究表明:在不同掺杂浓度中,Eu 3+离子浓度为4%时其相对发射强度最强。在三个不同的煅烧温度中,经800 ℃煅烧的样品其发光效果最好。此外还观察到电荷转移激发态以及基质、Gd 3+与Eu 3+之间的能量传递。激发谱包含三部分,即电荷转移带、Eu 3+的4f内壳层电子跃迁和Gd 3+的激发谱。 相似文献
9.
Nanostructured Gd 2O 3:Eu 3+ and Li + doped Gd 2O 3:Eu 3+ thin films were prepared by pulsed laser ablation technique. The effects of annealing and Li + doping on the structural, morphological, optical and luminescent properties are discussed. X-ray diffraction and Micro-Raman investigations indicate a phase transformation from amorphous to nanocrystalline phase and an early crystallization was observed in Li + doped Gd 2O 3:Eu 3+ thin films on annealing. AFM images of Li + doped Gd 2O 3:Eu 3+ films annealed at different temperatures especially at 973 K show a spontaneous ordering of the nanocrystals distributed uniformly all over the surface, with a hillocks (or tips) like self-assembly of nanoparticles driven by thermodynamic and kinetic considerations. Enhanced photoemission from locations corresponding to the tips suggest their use in high resolution display devices. An investigation on the photoluminescence of Gd 2−xEu xO 3 ( x=0.10) and Gd 2−x−yEu xLi yO 3 ( x=0.10, y=0.08) thin films annealed at 973 K reveals that the enhancement in luminescence intensity of about 3.04 times on Li + doping is solely due to the increase in oxygen vacancies and the flux effect of Li + ions. The observed decrease in the values of asymmetric ratio from the luminescence spectra of Li + doped Gd 2O 3:Eu 3+ films at high temperature region is discussed in terms of increased EuO bond length as a result of Li + doping. 相似文献
10.
Zinc phosphate glasses doped with Gd 2O 3:Eu nanoparticles and Eu 2O 3 were prepared by conventional melt-quench method and characterized for their luminescence properties. Binary ZnO-P 2O 5 glass is characterized by an intrinsic defect centre emission around 324 nm. Strong energy transfer from these defect centres to Eu 3+ ions has been observed when Eu 2O 3 is incorporated in ZnO-P 2O 5 glasses. Lack of energy transfer from these defect centres to Eu 3+ in Gd 2O 3:Eu nanoparticles doped ZnO-P 2O 5 glass has been attributed to effective shielding of Eu 3+ ions from the luminescence centre by Gd-O-P type of linkages, leading to an increased distance between the luminescent centre and Eu 3+ ions. Both doped and undoped glasses have the same glass transition temperature, suggesting that the phosphate network is not significantly affected by the Gd 2O 3:Eu nanoparticles or Eu 2O 3 incorporation. 相似文献
11.
Binary (ZnO) 0.5(P 2O 5) 0.5 glasses doped with Eu 2O 3 and nanoparticles of Gd 2O 3:Eu were prepared by conventional melt-quench method and their luminescence properties were compared. Undoped (ZnO) 0.5(P 2O 5) 0.5 glass is characterized by a luminescent defect centre (similar to L-centre present in Na 2O-SiO 2 glasses) with emission around 324 nm and having an excited state lifetime of 18 ns. Such defect centres can transfer the energy to Eu 3+ ions leading to improved Eu 3+ luminescence from such glasses. Based on the decay curves corresponding to the 5D 0 level of Eu 3+ ions in both Gd 2O 3:Eu nanoparticles incorporated as well as Eu 2O 3 incorporated glasses, a significant clustering of Eu 3+ ions taking place with the latter sample is confirmed. From the lifetime studies of the excited state of L-centre emission from (ZnO) 0.5(P 2O 5) 0.5 glass doped with Gd 2O 3:Eu nanoparticles, it is established that there exists weak energy transfer from L-centres to Eu 3+ ions. Poor energy transfer from the defect centres to Eu 3+ ions in Gd 2O 3:Eu nanoparticles doped (ZnO) 0.5(P 2O 5) 0.5 glass has been attributed to effective shielding of Eu 3+ ions from the luminescence centre by Gd-O-P type of linkages, leading to an increased distance between luminescent centre and Eu 3+ ions. 相似文献
12.
We investigate the fundamental properties of films
resulting from the deposition of Eu 3+ doped Gd 2O 3
clusters. We first report that the crystalline structure of
clusters with diameter as low as 2.8 nm is still BCC (as in the
bulk phase at ambient temperature and pressure). No phase
transition to monoclinic structure is observed. We show that
contamination from air (formation of hydroxide) is important and
leads to the modification of the luminescence of the Eu 3+
ions. Furthermore, films protected from this contamination have
been fabricated and show a new feature (broad peak at 625 nm). It
means that contamination is not the only mechanism responsible for
the modification of the light emission spectrum. The crystal field
symmetry breaking induced by the surface also plays a major role.
Eventually, we show that the widening of the optical gap continues
for these very small clusters. We discuss this effect in the frame
of the quantum confinement model. 相似文献
13.
The cathodoluminescence (CL) intensities of Y 2SiO 5:Ce 3+, Gd 2O 2S:Tb 3+ and SrAl 2O 4:Eu 2+,Dy 3+ phosphor thin films that were grown by pulsed laser deposition (PLD) were investigated for possible application in low voltage
field emission displays (FEDs) and other infrastructure applications. Several process parameters (background gas, laser fluence,
base pressure, substrate temperature, etc.) were changed during the deposition of the thin films. Atomic force microscopy
(AFM) was used to determine the surface roughness and particle size of the different films. The layers consist of agglomerated
nanoparticle structures. Samples with good light emission were selected for the electron degradation studies. Auger electron
spectroscopy (AES) and CL spectroscopy were used to monitor changes in the surface chemical composition and luminous efficiency
of the thin films. AES and CL spectroscopy were done with 2 keV energy electrons. Measurements were done at 1×10 −6 Torr oxygen pressure. The formation of different oxide layers during electron bombardment was confirmed with X-ray photoelectron
spectroscopy (XPS). New non-luminescent layers that formed during electron bombardment were responsible for the degradation
in light intensity. The adventitious C was removed from the surface in all three cases as volatile gas species, which is consistent
with the electron stimulated surface chemical reaction (ESSCR) model. For Y 2SiO 5:Ce 3+ a luminescent SiO 2 layer formed during the electron bombardment. Gd 2O 3 and SrO thin films formed on the surfaces of Gd 2O 2S:Tb 3+ and SrAl 2O 4:Eu 2+,Dy 3+, respectively, due to ESSCRs. 相似文献
14.
Thin Er 3+, Yb 3+ co-doped Y 2O 3 films were grown on (1 0 0) YAG substrates by pulsed laser deposition. Ceramic targets having different active ion concentration were used for ablation. The influence of the rare-earth content and oxygen pressure applied during the deposition on the structural, morphological and optical properties of the films were investigated. The films deposited at the lower pressure, 1 Pa, and at 1/10 Er to Yb doping ratio are highly textured along the (1 1 1) direction of the Y 2O 3 cubic phase. In addition to the crystalline structure, these films possess smoother surface compared to those prepared at the higher pressure, 10 Pa. All other films are polycrystalline, consisting of cubic and monoclinic phases of Y 2O 3. The rougher surface of the films produced at the higher-pressure leads to higher scattering losses and different behavior of the reflectivity spectra. Optical anisotropy in the films of less than 0.004 was measured regardless of the monoclinic structure obtained. Waveguide losses of about 1 dB/cm at 633 nm were obtained for the films produced at the lower oxygen pressure. 相似文献
15.
The color rendering index (CRI) and structural stability of cerium doped yttrium aluminum garnet (YAG:Ce) based phosphors have been enhanced by replacing Y 3+ ions by larger radius ions (Tb 3+, Gd 3+, Eu 3+, and Sm 3+) at the dodecahedral site and replacing Al 3+ ions by larger ones (Ga 3+, Y 3+, Tb 3+, Gd 3+, and Sm 3+) at the octahedral site. These aluminum garnet crystalline powders were prepared by solvothermal reaction method at 300 °C for 48 h. The lattice constant values of synthetic aluminum garnet crystalline powders are larger than that of YAG and the emission wavelength of Ce 3+ ion of these samples is longer than that of YAG:Ce. FESEM and TEM studies revealed that the Ln 3Ga 2Al 3O 12 and Ln 3Al 2Al 3O 12 crystalline powders have 3-dimensional star-like morphology with submicron size and good crystallinity, while, Ln 3(LnAl)Al 3O 12 garnet crystalline powders were cubic crystalline phases and shaped as cubes with the round edge having an approximate diameter of about 200–400 nm. All the prepared powders were grown along (100) direction and crystallized into single crystal. Also, the effects of treatment time and reaction temperature on the structure of aluminum garnet crystalline powders have been investigated. 相似文献
16.
Alumina (Al 2O 3) powders doped with europium trivalent (Eu 3+) were prepared by a low-temperature (∼280 °C) combustion synthesis technique. When the powder was heat treated at 1200 °C for 2 h in the presence of flowing ammonia (NH 3), α-Al 2O 3 crystalline ceramic powders was obtained. The analysis of the luminescence showed that Eu 3+ was reduced to europium divalent (Eu 2+) after the heat-treatment process. Under ultraviolet (UV) lamp excitation ( λ=254 nm) these powders containing sub-microcrystalline structures present bright red (Al 2O 3:Eu 3+) and green (Al 2O 3:Eu 2+) luminescence indicating that this material is a potential candidate for applications in phosphor technology. 相似文献
17.
The synthesis, morphological characterization, and optical properties of colloidal, Eu(III) doped Gd2O3 nanoparticles with different sizes and shapes are presented. Utilizing wet chemical techniques and various synthesis routes, we were able to obtain spherical, nanodisk, nanotripod, and nanotriangle-like morphology of Gd2O3:Eu3+ nanoparticles. Various concentrations of Eu3+ ions in the crystal matrix of the nanoparticles were tested in order to establish the levels at which the concentration quenching effect is negligible. Based on the luminescence spectra, luminescence lifetimes and optical parameters, which were calculated using the simplified Judd–Ofelt theory, correlations between the Gd2O3 nanoparticles morphology and Eu3+ ions luminescence were established, and allowed to predict the theoretical maximum quantum efficiency to reach from 61 to 98 %. We have also discussed the impact of the crystal structure of Gd2O3 nanoparticles, as well as coordinating environment of luminescent ions located at the surface, on the emission spectra. With the use of a tunable femtosecond laser system and the Z-scan measurement technique, the values of the effective two-photon absorption cross-section in the wavelength range from 550 to 1,200 nm were also calculated. The nonlinear optical measurements revealed maximum multi-photon absorption in the wavelength range from 600 to 750 nm. 相似文献
18.
Gd 2O 3:Eu 3+ rods were successfully obtained by microwave heating the as-prepared substance, which templated by surfactant assemblies of gadolinium hydroxide and europium hydroxide, formed in a reaction between Gd(NO 3) 3-Eu(NO 3) 3 and urea. Transmission electron microscopy (TEM) characterizations indicated that the synthesized rods with an averaging diameter of 100-150 nm and agglomerates slightly. Powder X-ray diffraction (XRD) results indicated that the resultant rods were cubic Gd 2O 3. The luminescent of Gd 2O 3:Eu 3+ rods were investigated by photoluminescence (PL). Upon excitation with 257 and 277 nm, respectively, Gd 2O 3:Eu 3+ rods show a strong red emission line at around 611 nm. Furthermore, this novel method required a very short heating time, thus reducing the energy consumption. 相似文献
19.
Red-emitting Eu 3+-doped Gd 2O 3 spherical powders were directly precipitated using a polyol method. The as-synthesized powders consist of agglomerates with a spherical shape and a size ranging between 0.4 and 0.6 μm. Each agglomerate is nanostructured and consists of a packing of nanocrystallites (3–5 nm) of a bcc oxide phase whose luminescence presents original features in comparison with bulk materials. The powders were further calcinated and the size of both crystallites and agglomerates, the crystalline structure and the luminescence were studied as a function of the annealing temperature. For temperatures lower than 900 °C, the samples obtained are highly crystalline and possess the classical Eu 3+ red luminescence. For optimized temperature, the morphology of the particles can be preserved leading to spherical, dense, luminescent and almost monodisperse oxide powders, 0.5 μm in size. PACS 81.07.Bc; 81.07.Wx; 81.16.Be; 75.50.-y; 42.70.-a 相似文献
20.
Spectra of Eu 3+ in various dielectric matrices (Gd 2O 3:Eu 3+, Y 2O 3:Eu 3+, Eu 2O 3, and mSiO 2/Gd 2O 3:Eu 3+ mesoporous particles) are studied by local cathodoluminescence. The results allowed identification of the local environment of Er 3+ ions in amorphous samples and detection of the monoclinic Eu 2O 3 phase impurity in samples with yttrium oxide. The cathodoluminescence spectra of chemically pure Y 2O 3, Eu 2O 3, and Gd 2O 3 are recorded. Conclusions about the structural features of the materials are made and confirmed by other methods (XRD and EPMA). 相似文献
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