Codoped Yttrium Oxide Research Articles

Electrical study of bismuth and zinc codoped yttrium oxide prepared by wet chemical method

Electrical study of bismuth and zinc codoped yttrium oxide prepared by wet chemical method

Luminescence Study of Red Light Emitting Y2O3:Sm3+ Nanophosphors and Enhancement by Co-doping with Gadolinium oxide

This work presents the optical and structural properties of samarium oxide doped and gadolinium oxide co-doped yttrium oxide nanophosphors prepared by Combustion method. The photoluminescence emission intensity was maximum for 2wt% Sm3+ doped Y2O3 powders, that results 4G5/2 -6H7/2 transition within Samarium, emits red light at 608 nm under the excitation of 260 nm. In the case of co-dopant, maximum intensity is obtained for 3wt% Gd3+ under the excitation of 255 nm.The Y:Sm:Gd exhibit luminescence intensity of 4.21 times more than that of Y:Sm nanophosphors. These results indicate that the prepared nanophosphors can be used in optoelectronic devices.

Up-conversion luminescence of hafnium, erbium, ytterbium and lithium co-doped yttrium oxide

UP-conversion luminescence of hafnium, erbium, ytterbium and lithium multiple doped yttrium oxide powders are presented. The measured luminescent spectra were obtained using two different lasers with wavelengths of 980 and 1534 nm; emission peaks were observed in the ranges of 530–580 nm (green emission), 630–680 nm (red emission), 960–1100 nm (infrared emission) and 1510 to 1560 (infrared emission) corresponding to the different intra electronic energy levels transitions of the Er3+ and Yb3+ ions. These emission peaks manifest the interactions between these ions that propitiate the phenomenon of up-conversion. The incorporation of lithium in the samples allowed an increase in the luminescent emission of up to 88% for the red emission and up to 12% for the emission in the IR range with respect to the samples that were not doped with lithium. The powders, object of this study, were synthesized by means of the solvent evaporation technique using nitrates and chlorides as precursors. The analysis of XRD showed a cubic crystalline structure of yttrium oxide with the spatial group: Ia-3 (206). The obtained SEM images showed a granular morphology only for samples doped with lithium with dimensions less than a micron. The chemical composition was obtained by measurements of EDS and FT-IR and finally the decay times of the different luminescent emissions are also reported.

Facile Combustion Synthesis of (Y,Pr)2O3 Red Phosphor: Study of Luminescence Dependence on Dopant Concentration and Enhancement by the Effect of Co-dopant

Abstract There occurs a great interest in explaining the dependence of dopant concentration on the luminescence efficiency of rare earth oxides. Unambiguously, this study explains that luminescence intensity increases with increase in dopant concentration only up to optimised value. The syntheses of doped and co-doped yttrium oxide (Y2O3) nanophosphors in this study were carried out by making use of combustion method. This method produces the nanophosphors that have sizes ranging between 5 and 20 nm as confirmed by transmission electron microscopy. X-ray diffraction pattern confirms that the incorporation of praseodymium oxide (Pr3+) and gadolinium oxide (Gd3+) does not cause any change in the cubic structure of Y2O3. The phase purity has been confirmed by Fourier transform infrared spectrum. Diffuse reflectance spectra reveal that the bandgap increases with increase in annealing temperature. Bandgap has been calculated by making use of the Kubelka–Munk function. Strongest emission was observed at 605 nm with 2 wt% of Pr3+ as optimised concentration. Replacement of Y3+ by Gd3+ partially enhances the 605-nm emission linearly. The [Y:Pr:Gd] exhibits luminescence intensity of 2.705 times more than that of Y:Pr nanophosphors. This is for the first time our team has made a detailed study regarding the effects of co-doping in the case of Y2O3:Pr powders. We have successfully presented the changes that happen to the particle after co-doping especially in the particle size and luminescence properties.

Red light emission of Y2O3:Eu3+ nanophosphors and luminescent enhancement by the addition of gadolinium oxide as co-dopant

This work presents the optical and structural properties of rare earth-doped and co-doped yttrium oxide nanophosphors. Europium oxide and gadolinium oxide-doped and co-doped Y2O3 phosphors were synthesized by make use of combustion method followed by annealing to different temperatures in order to obtain much more good crystallinity. The X-ray diffraction and Fourier transform infrared spectroscopy confirms the structural formation and phase purity of the compound. The diffuse reflectance spectra of doped and co-doped Y2O3 powder were analysed. It was found that there appears shifting of absorption edge towards longer wavelength region when compared to pure yttrium powder. The band gap was calculated by make use of Kubelka–Munk function. It was noticed that band gap increases with annealing temperature. The dependence of doping concentration, pH and annealing temperature on photoluminescence properties were studied in a systematic manner. The PL emission intensity was maximum for 6 wt% Eu3+-doped Y2O3 powders that results 5D0–7F2 transition within europium and emits red light at 612 nm under the excitation of 260 nm. In the case of co-dopant, maximum intensity is obtained for 7 wt% Gd3+ under the excitation of 255 nm.

Innovative silicon compatible materials for light emitting devices

The paper reports the potentialities of innovative silicon compatible materials for light emitting devices. In particular thin films of Er doped yttrium oxide have been synthesized by a technique totally compatible with ULSI processes. Through the structural characterization, we will verify the high stability of the film and the good dopant dissolution. Moreover, by the investigation of the optical properties, we will demonstrate that the use of this compound is effective to introduce more than 10 21 Er/cm 3 in optically active state, value that cannot be reached in other Si compatible materials. The influence of Er content on the optical properties will be described in details. Moreover, we will propose the introduction of a proper sensitizer for Er, bismuth, in the same thin film. In particular, we will show that the (Er+Bi) co-doped yttrium oxide is a perfect host to overcome another important drawback of Er doped materials that is its low absorption cross section. The influence of Bi and Er contents on optical properties will be extensively discussed along the paper. Through the optimization of ratio between Bi and Er concentrations, high energy transfer efficiency will be reached with simultaneously a consistent increase of the effective Er cross section. A factor of more than three orders of magnitude have been obtained with respect to the direct excitation of Er.

Photoluminescent and Thermoluminescent Studies of Dy3+ and Eu3+ Doped Y2O3 Phosphors.

Eu3+ doped and Dy3+ codoped yttrium oxide (Y2O3) phosphors have been prepared using solid-state reaction technique (SSR). The prepared phosphors were characterized by X-ray diffractometer (XRD), energy dispersive X-ray (EDX) spectroscopy, scanning electron microscopy (SEM) and Fourier transforms infrared spectroscopy (FTIR) techniques. Photoluminescence (PL) and Thermoluminescence (TL) properties were studied in detail. PL emission spectra were recorded for prepared phosphors under excitation wavelength 254nm, which show a high intense peak at 613nm for Y2O3:Dy3+, Eu3+ (1:1.5mol %) phosphor. The correlated color temperature (CCT) and CIE analysis have been performed for the synthesized phosphors. TL glow curves were recorded for Eu3+doped and Dy3+codoped phosphors to study the heating rate effect and dose response. The kinetic parameters were calculated using peak shape method for UV and γ exposures through computerized glow curve deconvolution (CGCD) technique. The phosphors show second order kinetics and activation energies varying from 5.823 × 10- 1 to 18.608 × 10- 1eV.

Luminescence properties of Y2O3:Bi3+, Yb3+ co-doped phosphor for application in solar cells

Bismuth (Bi3+) and ytterbium (Yb3+) co-doped yttrium oxide (Y2O3) phosphor powder was successfully synthesised using the co-precipitation technique. The X-ray diffraction (XRD) patterns confirmed that a single phase cubic structure with a Ia-3 space group was formed. The visible emission confirmed the two symmetry sites, C2 and S6, found in the Y2O3 host material and revealed that Bi3+ ions preferred the S6 site as seen the stronger emission intensity. The near-infrared (NIR) emission of Yb3+ increased significantly by the presence of the Bi3+ ions when compared to the singly doped Y2O3:Yb3+ phosphor with the same Yb3+ concentration. An increase in the NIR emission intensity was also observed by simply increasing the Yb3+ concentration in the Y2O3:Bi3+, Yb3+ phosphor material where the intensity increased up to x = 5.0mol% of Yb3+ before decreasing due to concentration quenching.

Structural, Morphological and Optical Study of Bismuth and Zinc Co-Doped Yttrium Oxide Prepared by Solvothermal and Wet Chemical Method

Structural, Morphological and Optical Study of Bismuth and Zinc Co-Doped Yttrium Oxide Prepared by Solvothermal and Wet Chemical Method

Efficient energy transfer from Bi to Er ions in Y2O3 thin films

Although in the last decades rare earths (REs)-containing materials have been proposed as active media in Si compatible light sources, the reached optical efficiency is still limited by the low REs excitation cross section. In this work, the introduction of Bi as an Er sensitizer in a Si-compatible yttrium oxide thin film has been proposed in order to overcome this limit. The stabilization of optically active Bi3+ ions in place of Y3+ in the two reticular sites, S6 and C2, of Y2O3 was demonstrated. Photoluminescence (PL) and photoluminescence excitation measurements have revealed the existence of two different intense emission bands in the visible range ascribed to Bi3+ in the two reticular sites. They can be selectively excited by properly changing the excitation wavelength. Moreover, the Bi3+→Er3+ energy transfer processes in the (Bi+Er)-codoped samples were demonstrated for both Bi3+ sites by the spectral overlap between the Bi emission bands and Er excitation peaks. We estimated an Er emission enhancement by a factor of about 80 for the C2 site and 16 for the S6 site with respect to the Er direct excitation. By the recorded reduction of the Bi PL intensities and the shortening of the related lifetimes in presence of Er ions, the energy transfer efficiencies were evaluated to be about 70% for the Bi (C2) and 35% for the Bi (S6). These interesting findings suggest (Bi+Er)-codoped yttrium oxide as an efficient Si-compatible material for photonic applications.

Temperature induced upconversion behaviour of Ho3+-Yb3+ codoped yttrium oxide films prepared by pulsed laser deposition

Pulsed laser deposited Ho3+-Yb3+ codoped yttrium oxide films were grown on silicon substrates in vacuum at different substrate temperatures (373, 573, 773 and 973 K). The deposited films have shown a phase transition on increasing the substrate temperature, as confirmed by the X-ray diffraction analysis. The grain distribution and surface roughness of the deposited thin films have been estimated by atomic force microscopy measurements. In the optical properties study upconversion luminescence at 547, 656 and 758 nm was revealed upon 980 nm excitation. 773 K was found to be the best substrate temperature owing to the thickest deposited layer, as indicated by Auger depth profile analysis of the prepared films. A non-tunable bright green upconversion emission due to the involvement of a two photon process was established and a possible excitation-emission mechanism is explained by using an energy level diagram of the dopant ions.

Photon Up-Conversion with Lanthanide-Doped Oxide Particles for Solar H2 Generation

Up-conversion (UC) of infrared (IR) photons into visible radiation constitutes a promising strategy to enhance the light harvesting efficiency of photovoltaic and photoelectrochemical devices. In the present study, we integrate Er3+/Yb3+-codoped yttrium oxide (Y2O3) submicrometric particles with outstanding up-conversion properties into mesoporous titanium oxide (TiO2) structures sensitized with cadmium selenide (CdSe) for solar hydrogen generation. We demonstrate that the incorporation of these up-converting particles (UCP) leads to effective H2 generation with IR photons. Moreover, based on the analysis of the emission lifetimes, we show that the optical interaction between the emitting UCPs and the CdSe absorber occurs via a radiative emission–reabsorption process. The low cost and toxicity and excellent chemical and thermal stability of our UC phosphors allow envisaging them as real candidates for the new generation of long-term photoelectrochemical devices for solar H2 generation.

Broadband down-conversion in Bi3+–Yb3+-codoped yttrium and yttrium–aluminum oxides

Comparative study of the broadband down-conversion processes in Bi3+–Yb3+-codoped yttrium oxide (Y2O3) and various yttrium–aluminum oxides (Y3Al5O12, YAlO3 and Y4Al2O9) has been performed from the point of view of search for materials suitable for enhancement of efficiency of silicon solar cells. The studied materials in the form of nanopowders have been synthesized by sol–gel method and characterized by X-ray powder diffraction, scanning electron microscopy and luminescence techniques. Relative down-conversion efficiency for studied materials has been estimated. It was shown that optimal concentration of Yb3+ ions should be 2–4 at.% simultaneously with Bi3+ ions in the amount of about 1 at.%. Such dopants content provides the highest emission intensity of Yb3+ ions in near-infrared when excited into Bi3+ ions absorption in ultraviolet. Perspectives of the studied materials for enhancement of silicon solar cells are discussed.

Influences of Doping and Annealing on the Structural and Photoluminescence Properties of Y2O3 Nanophosphors

This paper reports the structural and optical properties of rare earth doped and codoped yttrium oxide nanophosphors. Dysprosium (Dy(3+)) and Terbium (Tb(3+)) doped and codoped yttrium oxide (Y2O3) phosphors were prepared by combustion synthesis method and subsequently annealed to high temperature to eliminate the hydroxyl group (-OH) and to get more crystallinity. The formation of compounds was confirmed by the X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR). The diffuse reflectance spectra (DRS) of doped and codoped Y2O3 powder phosphors were measured and it is observed that the absorption edge of the doped samples is shifted towards blue region with respect to undoped sample. The bandgap of the prepared samples were evaluated with the help of Kubelka-Munk function using Diffuse Reflectance Spectra (DRS) and an increase in bandgap was observed with the decrease in crystallite size. A strong characteristics emission from Tb(3+) and Dy(3+) ions was identified and the influence of doping concentration and annealing temperature on photoluminescence properties was systematically studied. Transfer of energy was observed in dysprosium-terbium codoped Y2O3 nanophosphor at room temperature from Dy(3+) ions to Tb(3+) ions.

Ultraviolet upconversion luminescence enhancement in Yb 3+/Er 3+-codoped Y 2O 3 nanocrystals induced by tridoping with Li + ions

Ultraviolet (UV) upconversion (UC) luminescence in Yb 3+/Er 3+-codoped yttrium oxide (Y 2O 3) nanocrystals can be enhanced by orders of magnitude via tridoping further with Li + ions under diode laser excitation of 970 nm. Sensitized three-photon UC radiations at 390 and 409 nm, corresponding to the 4 G 11/2→ 4 I 15/2 and 4 H 9/2→ 4 I 15/2 of Er 3+ ions, respectively, present an enhancement time of about 33 times, which is larger than the 24 times enhancement for the UC green radiation. The UV UC radiation at 320 nm that corresponds to the 2 P 3/2→ 4 I 15/2 of Er 3+ ions has also been greatly enhanced. Theoretical calculations interpret that all the observed enhancement times of UV UC radiations arise from the prolonged lifetimes of their intermediate states.

Rare-Earth-Doped and Codoped Y2O3Nanomaterials as Potential Bioimaging Probes

The synthesis and characterization of various rare-earth (RE)-doped and codoped yttrium oxide (Y 2O 3) nanomaterials were undertaken in the current work. RE dopants such as terbium (Tb), europium (Eu), and erbium (Er) were successfully doped, and ytterbium (Yb)−Er was codoped into Y 2O 3 nanomaterials. The as-synthesized nanomaterials are highly dispersed in the organic phase. X-ray diffraction peaks can be assigned to cubic Y 2O 3, which confirms the crystallinity of the as-prepared Y 2O 3 samples. Room temperature photoluminescence (PL) spectra showed characteristic emission peaks of Tb-, Eu-, and Er-doped Y 2O 3 samples. Up-conversion spectra of green and red emissions were also shown for Er−Yb-codoped Y 2O 3 samples. It was found that the intensities of the green and red emissions could be altered by varying the dopant concentration. The nanocrystals were surface-functionalized with an amine (NH 2) group via a reverse microemulsion method. The amine groups render the nanocrystals water-soluble and als...

Luminescence characteristics of Yb 3+, La 3+ codoped yttrium oxide nanopowders

Luminescence characteristics of Yb 3+, La 3+ codoped yttrium oxide nanopowders were investigated. The grain size and the crystallinity of (Yb 0.05Y 0.90La 0.05) 2O 3 nanopowders increase with the increase of calcination temperature. The average grain size of the nanopowders calcined at 1100 °C is 66 nm and its cooperative up-conversion luminescence centered at 498 nm was detected due to nanometer size effect and perfect crystallinity. However, the cooperative up-conversion luminescence of (Yb 0.05Y 0.90La 0.05) 2O 3 transparent ceramics was not detected.

ChemInform Abstract: The Effect of Particle Morphology and Crystallite Size on the Upconversion Luminescence Properties of Erbium and Ytterbium Co‐Doped Yttrium Oxide Phosphors.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The Effect of Particle Morphology and Crystallite Size on the Upconversion Luminescence Properties of Erbium and Ytterbium Co-doped Yttrium Oxide Phosphors

Phosphor particles (ca. 60 nm in size) of yttrium oxide co-doped with Er3+ and Yb3+ ions were prepared by a precipitation method in the presence of EDTA. Their physical properties were compared to much larger particles (ca. 600−800 nm in size) prepared in the absence of EDTA. All of the particles were shown to have crystallized in the cubic phase, and all exhibited blue, blue-green, and green-yellow upconversion emission when excited with laser light of wavelength equal to 632.8 nm. These upconversion emissions were shown to be excited by a two-photon process. The most intense yellow-green upconversion emission occurs when the crystallite size is between 75 and 200 nm and the particle size is 600 to 800 nm. Cross-relaxation processes between Er3+ ions are suggested to be responsible for the more efficient upconversion in the larger particles. There is evidence from spectra taken in the temperature range 30 to −190 °C that there are two different hot bands in the given region of the spectrum. These two emission manifolds are explained as arising from the two different Er3+ lattice sites in the cubic Y2O3:Er3+ structure. When using red excitation (rather than infrared excitation), the presence of Yb3+ was found to be detrimental, as it diminished the upconversion intensity.