Doped Y2O3 Nanoparticles Research Articles

Size-Dependent High-Pressure Behavior of Pure and Eu3+-Doped Y2O3 Nanoparticles: Insights from Experimental and Theoretical Investigations.

We report a joint high-pressure experimental and theoretical study of the structural, vibrational, and photoluminescent properties of pure and Eu3+-doped cubic Y2O3 nanoparticles with two very different average particle sizes. We compare the results of synchrotron X-ray diffraction, Raman scattering, and photoluminescence measurements in nanoparticles with ab initio density-functional simulations in bulk material with the aim to understand the influence of the average particle size on the properties of pure and doped Y2O3 nanoparticles under compression. We observe that the high-pressure phase behavior of Y2O3 nanoparticles depends on the average particle size, but in a different way to that previously reported. Nanoparticles with an average particle size of ~37 nm show the same pressure-induced phase transition sequence on upstroke and downstroke as the bulk sample; however, nanoparticles with an average particle size of ~6 nm undergo an irreversible pressure-induced amorphization above 16 GPa that is completed above 24 GPa. On downstroke, 6 nm nanoparticles likely consist of an amorphous phase.

Efficient route for preparation of Nd3+ doped Y2O3 nanoparticles at intermediate temperature

Yttrium oxide nanoparticles are one of the proper host materials for rare-earth elements. The rare-earth ions doped in yttrium oxide nanoparticles have medical applications such as biological imaging and photonic applications such as waveguides in the infrared region, laser mediums, sensitizers, LEDs, etc. The preparation of rare-earth ion-doped Y2O3 nanoparticles is usually done through the solid-state process and at a very high temperature, such as 1200 °C. In this research, using the solid-state process and during multi-step heat treatment at temperatures of 210 °C, 380 °C, and 500 °C, white nanopowders of Nd:Y2O3were prepared in 6 h. The produced nanopowders were studied using various characterization methods. The results showed that the produced nanopowders have a cubic structure and an average particle size between 22 and 65 nm.

Near-infrared light harvesting of upconverting Y2O3:Er3+ nanoparticles and their photovoltaic application

Light harvesting plays a significant role in the enhancement on photovoltaic performance. It is closely associated with the photocurrent of solar cells. It is possible to improve light harvesting by material substitution as well as expansion of absorptive edge. Therefore, upconversion characteristics is one of promising solutions for better light harvesting. Upconverting materials emit visible light which is available for photoconversion after they absorb invisible near-infrared (NIR) light. In this study, Er3+ doped Y2O3 (Y2O3:Er3+) nanoparticles were used as upconverting material. Its strong emissions of green and red light corresponding to 2H11/2 and 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 transitions were clearly demonstrated under NIR irradiation of 975 nm wavelength. These emissions were apparently absorbed by dye-sensitized electrode. Based on these results, Y2O3:Er3+ nanoparticles were introduced into dye-sensitized solar cells (DSCs). After incorporating Y2O3:Er3+ nanoparticles, photovoltage was increased due to its high band-gap energy of about 5 eV. On the other hand, the photocurrent was decreased because of the decrease in adsorbed dye amount and electron paths. However, the photoconversion edge was obviously expanded. As a result, DSC performance was enhanced with optimum upconverting particles. It exhibited an efficiency of 8.03%, which was higher than that of a conventional DSC.

Temperature sensing with Er3+ doped Y2O3 nanoparticles operating within the 1st and 2nd biological window: The influence of particle size on the relative sensitivity of thermally decoupled levels

The luminescent properties of three nanocrystalline samples of Y2O3:Er3+ produced via PVA-assisted sol-gel route, with mean particle diameter of 21, 44 and 86 nm, were investigated aiming their application as optical temperature sensors within the first and second biological windows. Luminescence spectra were analyzed using three different wavelengths (532 nm, 660 nm and 800 nm) as excitation sources. The three samples exhibited up to four emission bands centered at 660 nm, 800 nm, 860 nm and 1000 nm, which were related to the 4F9/2 → 4I15/2, 4I9/2 → 4I15/2, 4S3/2 → 4I13/2 and 4I11/2 → 4I15/2 transitions of Er3+, respectively. Three luminescence intensity ratio (LIR) schemes associated with thermally decoupled levels were proposed and their dependence on ambient temperature was investigated, two for excitation at 660 nm and one for excitation at 800 nm. In all the three cases, excitation and emission wavelengths were within the first or second biological window. Relative sensitivities of up to 2.02 ± 0.06% K−1 were obtained, with good repeatability and reproducibility and with temperature uncertainties below 1 K. The influence of particle size on luminescence intensity and sensor sensitivity was also presented and discussed, considering the potential applications. The results showed that particle size can affect the sensitivity of each LIR differently depending on the phonon-assisted processes involved.

Modified Eu3+ doped Y2O3 Nanoparticles as Turn-on Fluorescence Sensor for Sensitive Determination of Methamphetamine

Modified Eu3+ doped Y2O3 Nanoparticles as Turn-on Fluorescence Sensor for Sensitive Determination of Methamphetamine

Temperature Sensing with Er3+ Doped Y2o3 Nanoparticles Operating within the 1st and 2nd Biological Window: The Influence of Particle Size on the Relative Sensitivity of Thermally Decoupled Levels

Temperature Sensing with Er3+ Doped Y2o3 Nanoparticles Operating within the 1st and 2nd Biological Window: The Influence of Particle Size on the Relative Sensitivity of Thermally Decoupled Levels

Optical processes and apparent increase of optical band gap in Y2O3:Eu2+ nanoparticles synthesised by a gradually-heated solution combustion method

We report optical absorption and emission features of Eu doped Y2O3 nanoparticles synthesised by a gradually-heated solution combustion method. An X-ray diffraction analysis reveals that the samples exhibit body centred cubic structure. The crystallite size of an undoped Y2O3 sample was estimated to be ~19.87 nm but it is found to increase up to 46.38 nm in a sample doped with 4% Eu. The samples have spherical structure of diameter ~23–57 nm. Analysis of optical absorption spectra indicates an apparent increase of optical band gap from 5.00 eV to 5.24 eV after the doping. This apparent widening of band gap is explained with reference to the Burstein-Moss effect. The Eu doped samples produce a primary emission band at 447 ± 1 nm and a secondary band between 480 and 630 nm. Analysis reveals that the primary band is composed of two overlapping components with peak maxima at 446 ± 1 nm and 455 ± 3 nm. These emission bands are attributed to the transition from degenerate 5d → 4f level of Eu2+ ion. The absorption and emission features have been discussed with reference to an energy band model.

Laser-synthesized Ce3+ and Pr3+ doped Y2O3 nanoparticles and their characteristics

Ce3+:Y2O3, Pr3+:Y2O3, Ce3+:(LaxY1−x)2O3, Pr3+:(LaxY1−x)2O3 nanoparticles were fabricated by laser ablation. The nanopowders consisted of spherical particles with average size of 14 ÷ 17 nm. Ytterbium fiber laser operated in pulse mode at 5 kHz repetition rate and average radiation power of 255 W. The intensity of the laser radiation in focal spot was about 106W/cm2with close-to-Gaussian profile. The structural and morphological properties of the nanoparticles were investigated employing TEM, BET, FT-IR, XRD analysis.

Bifunctional heater-thermometer Nd3+-doped nanoparticles with multiple temperature sensing parameters

Achieving a combination of real-time diagnosis and therapy in a single platform with sensitive thermometry and efficient heat production is a crucial step towards controllable photothermal therapy. Here, Nd3+-doped Y2O3 nanoparticles prepared using the combined Pechini-foaming technique operating in the first and second biological windows were demonstrated as thermal sensors within the wide temperature range of 123–873 K, and as heaters with a temperature increase of 100 K. Thermal sensing was performed based on various approaches: luminescence intensity ratio (electronic levels; Stark sublevels), spectral line position and line bandwidth were used as temperature-dependent parameters. The applicability of these sensing parameters, along with relative thermal sensitivity and temperature resolution, are discussed and compared. The influence of Nd3+-doping concentration on thermometer and heater efficiency was also investigated.

Chemically and thermally stable lanthanide-doped Y2O3 nanoparticles for remote temperature sensing in catalytic environments

Luminescent nanoparticles have great potential for remote temperature sensing. Mapping of high temperature profiles under harsh conditions that are common in chemical reactors requires new thermally and chemically stable (nano)probes. Here, we report temperature dependent luminescence of Yb3+/Er3+-, Dy3+- and Eu3+-doped Y2O3 nanoparticles (NPs). We have deposited these lanthanide-doped Y2O3 NPs on α-Al2O3, a non-porous catalyst support material. The NPs are strongly adsorbed on the surface and no sintering was observed upon heating to 900 K for 12 h. The high chemical and thermal stability of Y2O3 makes these nanoprobes ideal for sensing in catalytic environments. A systematic study of the three types of luminescent NPs reveals that the temperature dependent luminescence of Yb3+/Er3+, Dy3+ and Eu3+ serves different temperature ranges: lower T regime (300–800 K, accuracy < 5 K) for Yb3+/Er3+, intermediate T for Dy3+ (400–900 + K, accuracy < 15 K) and high T for Eu3+ (550–900 + K, accuracy < 12 K). The superior thermal and chemical stability of the Y2O3/α-Al2O3 host in combination with different luminescent lanthanide dopants results in a robust system that can be tailored to monitor temperatures in different regimes with the highest possible sensitivity.

Y2O3:Nd3+ nanocrystals as ratiometric luminescence thermal sensors operating in the optical windows of biological tissues

Here, we report Nd3+-doped Y2O3 nanoparticles suitable for luminescence thermal sensing in the first and second biological windows. The nanoparticles were synthesized via the combined Pechini-foaming method. A ratiometric approach, based on the relative changes in the intensities of different emission bands corresponding to the Stark sublevels or excited levels, was applied to determine local temperature. The evaluated thermal sensitivities differed 5-fold times depending on the choice of transitions for the luminescence intensity ratio calculation. The temperature uncertainty was determined to be below 1 °C, which allows to perform sub-degree thermal sensing. The results of ex vivo experiment indicate that Nd3+-doped Y2O3 nanoparticles are promising candidates for real biological applications.

Optical temperature sensing behavior of Er[formula omitted]/Yb[formula omitted]/Tm[formula omitted]:Y[formula omitted]O[formula omitted] nanoparticles based on thermally and non-thermally coupled levels

Er3+/Yb3+/Tm3+ triply doped Y2O3 nanoparticles have been synthesized by solute combustion method. X-ray diffraction (XRD) and scanning electron microscopy (SEM) demonstrate that the prepared particles are cubic Y2O3 phase with the average size of ∼49 nm. The blue (Tm3+: 1G4→3H6), green (Er3+: 2H11∕2, 4S3∕2→4I15∕2) and red (Er3+: 4F9∕2→4I15∕2) upconversion (UC) emissions are observed upon a 980 nm excitation. Applying the fluorescence intensity ratio (FIR) technique, the optical temperature sensing behaviors are studied based on thermally coupled levels (2H11∕2 and 4S3∕2 of Er3+) and non-thermally coupled levels (1G4(b) (Tm3+) and 2H11∕2 (Er3+)), respectively. The results show that the absolute sensing sensitivity is much higher in the entire experimental temperature range, when the non-thermally coupled levels with different temperature dependences (1G4(b) (Tm3+) and 2H11∕2 (Er3+)) are selected as the thermometric index. The maximum absolute sensitivity is found to be as high as ∼1640×10−4 K−1 at 573 K. This demonstrates that an optical temperature sensor with high performance can be designed based on the Er3+/Yb3+/Tm3+:Y2O3 nanoparticles.

Transparent Er3+-Doped Y2O3 Ceramics with Long Optical Coherence Lifetime.

Er3+-doped Y2O3 nanoparticles (NPs) are used to synthesize transparent ceramics by hot isostatic pressing. Two sizes of NPs are studied, and 40 nm NPs show better performance than 200 nm NPs in transparent ceramics syntheses. The axial optical transmission through millimeter thickness of the prepared ceramics is about 80% in the wavelength range of 1000–2000 nm. For a sample with 11.5 ppm Er3+, the inhomogeneous broadening of the 4I15/2 to 4I13/2 transition for the C2 site is as low as 0.42 GHz (full width at half-maximum), and the homogeneous line width is 11.2 kHz at a temperature of 2.5 K and in a 0.65 T magnetic field. This indicates that a majority of Er3+ ions are sitting in sites with very low structural disorder.

Effect of charge transfer band on luminescence properties of Yb doped Y2O3 nanoparticles

Effect of charge transfer band on luminescence properties of Yb doped Y2O3 nanoparticles

Structural and optical properties of Tb3+ doped Y2O3 nanoparticles

Y2O3 luminescent nanoparticles were synthesized via new protocol of sol–gel method combined with a furnace firing in air, using metal salt as precursor and an epoxide for hydrolysis. Effects of rare earth (Tb3+) doping on structural and luminescence properties of the produced nanophosphors have been investigated. The obtained nanopowders were characterized by various techniques such as thermogravimetric analyser (TGA), differential thermal analyser (DTA), transmission electron microscopy (TEM), X-ray diffraction (XRD), photoluminescence spectroscopy (PL) and photoluminescence excitation (PLE). After thermal treatment at different temperatures in air, the powder with an average particle size of 50 nm presents a green luminescence band in the visible range (544 nm). The intensity of the obtained PL band increases with of thermal treatment temperature and the PLE spectra present an intensive band in UV-range corresponding to Y2O3 band-gap. Different origins of this evolution will be discussed.

Possible size control and emission characteristics of Eu3+–doped Y2O3 nanoparticles synthesized by surfactant-assembly

Yttrium oxide nanoparticles doped with 2.0wt% Eu (Eu@Y2O3) were synthesized via the surfactant-assembly method. The average diameter of Eu@Y2O3 (dav) depends on the alkyl chain number (N) of the sodium alkyl sulfates employed as surfactants. Using surfactants with N=8, 10, and 12, Eu@Y2O3 with dav=35, 200, and 500nm, respectively were obtained. Such changes in dav are ascribed to the difference in the micelle aggregation numbers, supporting the use of rare-earth ions in the assembly. The Eu@Y2O3 particles synthesized presently emitted through Eu3+ transitions under UV excitation of Y2O3, making them applicable to nanoemitters.

Red, Yellow, Blue and Green Emission from Eu(3+), Dy(3+) and Bi(3+) Doped Y2O3nano-Phosphors.

Rare earth elements (RE=Eu(3+)& Dy(3+))and Bi(3+) doped Y2O3 nanoparticles were synthesized by urea hydrolysis method in ethylene glycol, which acts as reaction medium as well as a capping agent, at a low temperature of 140°C,followed by calcination of the obtained product. Transmission electron microscope (TEM) images reveals that ovoid shaped Y2O3 nanoparticles of around 22-24nm size range were obtained in this method. The respective RE and Bi(3+) doped Y2O3 precursor nanoparticles when heated at 600 and 750°C, retains the same shape as that of the as-synthesized Y2O3 precursor samples. From EDAX spectra, the incorporation of RE ions into the host has been studied. XRD patternreveals the crystalline nature of the heated nanoparticles and indicate the absence of any impurity phase other than cubic Y2O3.However, the as-synthesized nanoparticles were highly amorphous without the presence of any sharp XRD peaks. Photoluminescence study suggests that the synthesized samples could be used as red (Eu(3+)), yellow (Dy(3+)), blue and green (Bi(3+))emitting phosphors.

Photoluminescence and Electroluminescence of Eu Doped Y2O3

In this paper, Eu doped Y2O3 nanophosphors are prepared at temperature 600oC by the combustion method. X-ray diffraction patterns confirm the formation of pure cubic phase of Y2O3. Electroluminescence of Eu doped Y2O3 has been investigated at different voltages by sandwitching the thick films between the conducting glass plate and aluminium electrode. Conducting transparent electrode has been obtained by depositing SnO2 layers over heated glass substrate. AC voltage of different frequencies was applied and EL intensity was measured with the help of photomultiplier tube. The intensity of EL increases with increasing voltage. PL decay characteristics of the Eu doped Y2O3 nanoparticles in the form of powder were measured.

Emission properties of Ln (Eu, Tb, Dy, Er)-doped Y2O3 nanoparticles synthesized by surfactant-assembly and their applications in visible color-tuning

We have prepared lanthanoid (Ln = Eu, Tb, Dy, and Er)-doped Y2O3 nanoparticles (YNPs) for producing nanomaterials showing emission in the visible region. YNPs were fabricated by means of surfactant assembly, and they had a diameter of 500 ± 200 nm. Under UV excitation, Ln-doped YNPs showed sharp emission spectra due to the 4f–4f transitions of Ln3+ in the YNP environment. The photoexcitation spectra of Ln-doped YNP comprised 4f–4f transitions and Ln3+ 4f–5d transitions, or charge transfer from the Y2O3 matrix to Ln3+; the bands in the latter case were broad. By appropriate choice of the excitation wavelength (λex), either Eu3+ or Tb3+ could be dominantly excited in the Eu3+ and Tb3+ co-doped YNP. At an appropriate λex, the co-doped YNP showed emission in the orange and green regions due to Eu3+ and Tb3+, respectively; alternatively, an intermediate color resulted because of additive color-tuning of the resources. The emission color can also be varied by changing the Eu–Tb doping ratio in the YNP, under a fixed λex. It was demonstrated that Eu3+ and Tb3+ emit almost independently, which makes such a color-tuning process feasible.

Morphology controlled Y2O3:Eu3+ nanophosphors with enhanced photoluminescence properties

Eu3+ doped Y2O3 is prepared by a co-precipitation method using ammonium hydrogen carbonate as precipitating agent. In the present work we studied the effect of different molar concentrations of Poly vinyl pyrrolidone (PVP) and 1-Thio-glycerol (TG) as capping agents to enhance the optical and morphological properties of Y2O3:Eu3+ nanophosphors. In addition, variation of pH was studied to control the particle size of the synthesized product. The polymer concentration (TG and PVP) was also optimized at different pH to get higher luminescence of Eu3+ doped Y2O3 nanoparticles (NPs). It was observed that pH of solution during synthesis and also its concentration affect the morphological and optical properties of Y2O3:Eu3+. The structural, morphological and optical properties were studied by an X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy and photoluminescence spectroscopy. XRD studies followed by Rietveld refinement confirmed the body-centered cubic structure of doped nanophosphors. It was observed that at optimized pH and polymer concentration the nanoparticles of Y2O3:Eu3+ have narrow size distribution and exhibited enhanced photoluminescent properties.