Co-doped Y2O3 Research Articles

Intense white light emission in Tm3+/Er3+/Yb3+ co-doped Y2O3–ZnO nano-composite

The Tm3+/Er3+/Yb3+ co-doped Y2O3–ZnO nano-composite is synthesized using the solution combustion technique. The structural morphology is monitored using x-ray diffraction, transmission electron microscopy and scanning electron microscopy. The Yb3+/Tm3+ co-doped nano-phosphor emits intense blue as well as weak red emissions, while Yb3+/Er3+ co-doped nano-phosphor emits strong green along with red emissions on excitation with 976 nm laser. Joining these together (i.e. Tm3+/Er3+/Yb3+ co-doped phosphor) give very strong white light, which is further verified by CIE coordinates (0.32, 0.36). The addition of ZnO with Y2O3 phosphor gives further enhancement in the intensity of white light. The possible reason for this enhancement is the removal of optical quenching sites.

Enhanced green upconversion luminescence in Ho3+ and Yb3+ codoped Y2O3 ceramics with Gd3+ ions

A detailed investigation on the effect of Gd3+ ions on the upconversion (UC) luminescence of Y2O3:Ho3+/Yb3+ was performed. The green UC emission intensity was obviously enhanced along with an increase in the relative content of Gd3+ ions from 0mol% to 70mol%, with a corresponding decrease in the Y3+ content from 91.9mol% to 21.9mol%. X-ray diffraction and decay time investigations confirmed that tridoping with Gd3+ ions can influence the local crystal field of the Y2O3 host lattice. Theoretical calculations illustrated that the enhancement in the green UC emission resulted from the induction of the Gd3+ ions, which increased the lifetimes in the intermediate 2F5/2 (Yb) and 5I6 (Ho) states, reduced the highest phonon cutoff energy of Y2O3 and dissociated the Yb3+ and Ho3+ ion clusters in the bulk ceramics.

Optical thermometry using FIR of two close lying levels of different ions in Y2O3:Ho3+–Tm3+–Yb3+ phosphor

The possibility of combustion synthesized Ho3+–Tm3+–Yb3+ codoped Y2O3 phosphor as temperature sensor using fluorescence intensity ratio (FIR) technique under a 980 nm excitation has been reported. The variation in FIR of blue upconversion emissions generated from two closely spaced levels of the Tm3+ and Ho3+ ions (1G4 and 5F3) as a function of temperature has been monitored up to 703 K. The maximum relative sensitivity has been found to be 3.38 × 10−3 K−1 which indicates that the present phosphor material can play a vital role for high optical thermometric purpose. The results imply that the FIR of two closely spaced levels of two different rare earth ions can also be used as temperature sensor.

Blue and green emission from Ce3+ and Tb3+ co-doped Y2O3 nanoparticles

Tb3+ doped Y2O3 nanoparticles of 4–10nm size were synthesized from nitrate precursors by the urea hydrolysis method in ethylene glycol medium at a low temperature of 140°C. Characteristic green emission of Tb3+ corresponding to 5D4→7FJ is observed to be very strong, which is further enhanced with heat treatment temperature. Characteristic blue color emission of Ce3+ ion originating from 5d→2F7/2 (424nm) and 2F5/2 (486nm) transitions are found to be very strong in as-synthesized Ce0.02Tb0.06Y1.92O3 nanoparticles. However, its luminescence intensity decreases with increase in heating temperature or increase in the particle size/crystallinity, whereas a weak emission peak of Tb3+ ion at 545nm is witnessed. The polycrystalline nature of the as-prepared sample changed to highly crystalline state when heated at an elevated temperature (1200°C).

White upconversion emission in Y2O3:Er3+–Tm3+–Yb3+phosphor

Er3+–Tm3+–Yb3+ codoped Y2O3 phosphor has been synthesized by optimized combustion synthesis process and its white light upconversion emission property is investigated using cheap 980nm diode laser excitation. Efficient red, green and blue light emission bands, necessary for attaining white light emission, are observed in the codoped sample. The concentration of each rare earth ion is adjusted to get the required emission. In this phosphor, interestingly, emission colour coordinates are found to almost independent on the excitation power density. The temperature sensing behaviour of the prepared samples has also been studied using fluorescence intensity ratio (FIR) technique.

Enriched green upconversion emission in combustion synthesized Y2O3:Ho3+–Yb3+ phosphor

Ho3+ and Yb3+ co-doped Y2O3 phosphor has been prepared by the combustion route and its upconversion emission has been studied by using a 980 nm diode laser excitation. The powder XRD measurement has shown cubic phase of the sample. Prepared phosphors have shown good upconversion intensity and exhibited UV to NIR upconversion emission bands. The co-doping of Yb3+ in Y2O3:Ho3+ phosphor has found to enhance the Ho3+ emission intensity nearly ∼290 times. Interestingly, large part of the total upconversion intensity emitted by the sample was found to be concentrated around ∼545 nm which resulted pure green emission. For potential security applications, the upconversion based text reading concept has been demonstrated using this phosphor. The temperature sensing property of synthesized phosphor has also been studied by using the fluorescence intensity ratio of two nearby levels of green emission.

Photoluminescence study of Y2O3:Er3+-Eu3+-Yb3+ phosphor for lighting and sensing applications

The Er3+, Eu3+, and Yb3+ codoped Y2O3 phosphors have been synthesized by combustion synthesis process. For the structural information, the XRD analysis of the developed phosphor has been done. The frequency upconversion (UC) emissions in the codoped Y2O3 phosphor on excitation with 980 nm diode laser in the visible region have been performed and explained on the basis of excited state absorption and energy transfer process. The mechanism responsible in UC emissions was observed to involve two photon absorption and efficiency of the UC luminescence is significantly enhanced by introducing the Yb3+ ions. The tunability in colour of emitted radiation has been visualized by chromaticity diagram on increasing power of excitation source. The temperature sensing behaviour of developed phosphor material has been investigated using fluorescence intensity ratio technique.

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.

Yb3+和Er3+共掺杂的Y2O3, Y2O2S和NaYS2粉末材料的上转换发光

Yb³⁺和Er³⁺共掺杂的Y₂O₃, Y₂O₂S和NaYS₂粉末材料的上转换发光

Sensitization Effect of Yb3+ in Upconversion Luminescence of Eu3+Codoped Y2O3 Phosphor

For structural information, the X-ray diffraction analysis of Y2O3:Eu3+ phosphors codoped with Yb3+ synthesized by combustion synthesis process has been performed. The upconversion emission study of the Y2O3:Eu3+ phosphor codoped with Yb3+ ions on excitation with 980 nm diode laser in the visible region has been done. The upconversion emissions corresponding to the Eu3+ ions is due to sensitization from Yb3+ ions in developed phosphor, and has been explained on the basis of cooperative energy transfer process. The orange colour emitted from the codoped samples is visualized by CIE diagram. The results show the applicability of the present phosphor as suitable NIR (near infrared) to visible upconverter, and in other photonic devices.

Change in structural morphology on addition of ZnO and its effect on fluorescence of Yb3+/Er3+ doped Y2O3

Yb3+/Er3+ codoped Y2O3 phosphor and its composite with ZnO have been synthesized by combustion method. Morphology of the materials has been investigated using X-ray diffraction pattern (XRD) and scanning electron microscopy (SEM) techniques. XRD confirms the constituents as Y2O3 and ZnO, with average crystallite size of 112nm. On addition of ZnO, a small shifting in XRD pattern of Y2O3 is observed. SEM pattern suggests that the average particle size lies in micro-range (0.5μm). A dumble like structure is observed for hybrid material on annealing at 1473K. A strong green (525, 546nm) with weak blue (411nm) and red (657nm) emissions through upconversion has been observed from the phosphor on excitation with 976nm diode laser. The observed emissions involve 2H9/2→4I15/2, 2H11/2→4I15/2, 4S3/2→4I15/2 and 4F9/2→4I15/2 electronic transitions, respectively. The upconversion process has been confirmed by power dependence measurements and its slope value was found to be 1.85, 1.72 for green and red emissions, respectively. On addition of ZnO, the intensity of these emissions is enhanced several times. The reason behind the enhancement is discussed with the help of the emitting level lifetime. An interesting dual mode property (upconversion and downconversion) to the same material has been observed on excitation with 532nm laser source.

Sol–gel synthesis of Eu3+, Tb3+ co-doped Y2O3 scintillating nanopowders

AbstractY2O3: Eu3+, Tb3+ nanopowders were prepared via the sol–gel process, using yttrium pentadionate, europium, terbium nitrates, and ethanol as precursors. After the sol evaporation at 100°C, the formed gel was annealed from 300 to 900°C for 15 min, and the obtained nanopowders were analyzed by X-ray diffraction to characterize the microstructural behavior and the crystalline structure, which was determined as mainly cubic. The crystallite size varies from 8.6 to 30.9 nm, at 500 and 900°C, respectively. Transmission electron microscopy studies were carried out in order to analyze the microstructure and the size of crystallites. Three different Tb3+ atomic contents (0.005, 0.075, and 0.01 at.%) were used at a fixed Eu3+ level (2.5 at.%) with the aim of determining the relationship between the co-doping content and the scintillation intensity of the well-known 5Do→7F2 europium emission band at 611 nm. The results show that at higher Tb3+ contents, a quenching process occurs between Eu3+ and Tb3+; however, even with the lowest Tb3+ content (0.005 at.%), an increment on the scintillation light yield is observed compared with a Eu3+ monodoped sample.

Colour emission tunability in Ho3+–Tm3+–Yb3+ co-doped Y2O3 upconverted phosphor

The frequency upconversion (UC) emission throughout the visible region from the Y2O3:Ho3+–Tm3+–Yb3+ co-doped phosphors synthesized by using low temperature combustion process upon excitation with a diode laser operating at 980 nm have been presented. The colour emission tunability in co-doped phosphor has been observed on increasing the pump power and seen by the naked eyes. The tunability in colour emission has also been visualized by CIE chromaticity diagram. The variation in UC emission intensity of the 1G4 → 3H6 (Tm3+) and 5F3 → 5I8 (Ho3+) transitions lying in the blue region has been monitored with increase in the pump power and marked that their ratio can be used to determine the temperature. The developed phosphor has been used to record fingerprints. The observed most intense visible colour emission from the developed material may be used for photodynamic therapy and as an alternative of traditional fluorescent biolabels.

Effect of Eu, Tb codoping on the luminescent properties of Y2O3 hollow microspheres

Y2O3:Eu3+, Tb3+ hollow microspheres are prepared with different doping concentration of Eu3+ and Tb3+ ions and synthesizing temperatures from 700 to 1000°C via a urea-based homogeneous precipitation technique with colloidal melamine formaldehyde (MF) microspheres as templates followed by a subsequent calcination process. The resulted hollow microspheres were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and photoluminescence (PL) spectroscopy. The results of XRD indicate that the crystallinity of the synthesized samples increases with enhancing the calcination temperature. The photoluminescence spectra indicate the Eu3+ and Tb3+ co-doped Y2O3 microspheres show five main emission peaks: three at 591, 609 and 629nm originate from Eu3+ and two at 482 and 541nm originate from Tb3+, under excitation of 250–340nm irradiation. The luminescence color could be changed by varying the excitation wavelength. Different concentrations of Eu3+ and Tb3+ ions were induced into the Y2O3 lattice and the energy transfer from Tb3+ to Eu3+ ions in these phosphors was found.

Up-conversion luminescence in Ho3+ and Tm3+ co-doped Y2O3:Yb3+ fine powders obtained through aerosol decomposition

Fine yttrium oxide powders doped with Yb3+ and co-doped either with Tm3+ or Ho3+ were synthesized via spray pyrolysis at 900°C using 0.1M nitrate precursor. Synthesized powders were additionally thermally treated at 1100°C for 24h. The characterization was done through X-ray powder diffraction (XRPD), scanning electron microscopy (SEM) and photoluminescent measurements (PL). Generation of cubic bixbyte-structure with space group Ia-3 is confirmed in all samples. Spherical particles with the mean size of ∼400nm, generated through volume precipitation of much smaller nanograins, expose certain degree of porosity which alters particle morphology during additional thermal treatment. Powders optical characterizations include measurement of up-conversion emission spectra after excitation at 978nm, as well as determination of emission lifetimes and up-converted emission intensity dependence on excitation power. Dominant green (5F4, 5S2→5I8) and blue (1G4→3H6) emission is found for Ho3+ and Tm3+ samples, respectively. The amplified emission intensities and enhanced lifetime in thermally treated samples are correlated with the powders morphological and structural changes.

Infrared to visible upconversion in Ho3+/Yb3+ co-doped Y2O3 phosphor: Effect of laser input power and external temperature

In the present paper, Ho3+ doped and Ho3+/Yb3+ co-doped Y2O3 phosphors have been synthesized using solution combustion technique and characterized for its structure and upconversion (UC) fluorescence as a function of Yb3+ concentration. Effect of a variation in laser input power and external temperature on the UC emission intensity has been studied to explore the UC mechanism and temperature dependent behavior of the phosphor, respectively. On excitation with near infrared (NIR) light (976nm), the phosphor emits strong green emission along with relatively weak emission bands in red and blue regions at 553, 670 and 497nm due to 5S2→5I8, 5F5→5I8 and 5F3→5I8, respectively. The emission shows a decrease in intensity with an increase in external temperature, however contrary to the normal behavior of Ho3+, no significant change in the FIR (fluorescence intensity ratio) of 5F4→5I8 and 5S2→5I8 transitions is noted in the present host. This peculiar behavior of the sample with external temperature has been explained by temperature dependent lifetime study of the thermally coupled levels.

Fabrication of Er3+/Yb3+ co-doped Y2O3 transparent ceramics by solid-state reaction method and its up-conversion luminescence

Highly transparent Er3+/Yb3+ co-doped yttria ceramics were fabricated by a solid-state reaction method using high purity Y2O3, Er2O3 and Yb2O3 powders as starting materials and La2O3 as an additive. The microstructure evolution and optical properties of the ceramics were investigated. Fully dense Y2O3: Er3+, Yb3+ ceramics with mean grain size of about 60 μm were obtained by vacuum sintering at 1800 °C for 10 h. The highest transmittance of the ceramic sample is more than 75% in the range from 500 to 3000 nm. Under the 980 nm laser diode excitation, the ceramic sample exhibits intense up-conversion luminescence, which is centered at 561 and 662 nm respectively.

The optical properties of Eu3+ and Tm3+ codoped Y2O3 submicron particles

This report presents a fabrication result of nearly uniform-shaped color-tunable Y2O3 submicron particles codoped with Eu and Tm ions. The resulted particles were characterized by X-ray diffraction, field emission scanning electron microscope and field emission transmission electron microscope, whereas their optical properties were monitored by photoluminescence spectroscopy. The room temperature luminescence emission of synthesized particles was investigated in detail. It was shown that Eu3+ and Tm3+ codoped Y2O3 submicron particles exhibits red luminescence (612nm) under 255nm excitation, while the emission color of the same particles can be tuned to blue (459nm) under 320nm excitation. Different concentrations of Eu3+ and Tm3+ were induced into the Y2O3 lattice and the luminescence quenching was observed at high dopant concentrations.

Optical temperature sensor through infrared excited blue upconversion emission in Tm3 +/Yb3 + codoped Y2O3

An analysis of the intense blue upconversion emission at 476 and 488nm in Tm3+/Yb3+ codoped Y2O3 under excitation power density of 86.7W/cm2 available from a diode laser emitting at 976nm, has been undertaken. Fluorescence intensity ratio (FIR) variation of temperature-sensitive blue upconversion emission at 476 and 488nm in this material was recorded in the temperature range from 303 to 753K. The maximum sensitivity derived from the FIR technique of the blue upconversion emission is approximately 0.0035K−1. The results imply that Tm3+/Yb3+ codoped Y2O3 is a potential candidate for the optical temperature sensor.

Submicron Y2O3 particles codoped with Eu and Tb ions: Size controlled synthesis and tuning the luminescence emission

Eu3+ and Tb3+ codoped Y2O3 submicron particles were prepared using the simple urea homogeneous precipitation method. X-ray diffraction patterns revealed the synthesized particles to have a pure cubic Y2O3 structure. Field-emission scanning electron microscopy and field-emission transmission electron microscopy showed that the synthesized particles had almost uniform spherical shapes. The luminescence color emission of the synthesized particles could be tuned from red due to the effective 5D0→7Fj (j=0, 1, 2 and 3) transitions within Eu3+ to green due to the 5D4→7F5 transition within Tb3+ by switching the excitation wavelength from 255 to 310nm. Luminescence quenching was observed at high dopant concentrations. Strong and effective color-tunable emission is expected to find a wide range of applications in industry.