Pure Yttrium Oxide Research Articles

The Influence of CeO2 Concentration on Some Physical Properties of Y2O3 Thin Films

Thin films of pure yttrium oxide (Y2O3) and doped with cerium oxide (CeO2) were prepared by the chemical spray pyrolysis(CSP)method. The structural, optical and electrical properties of the prepared films were investigated. The analysis of X-ray diffraction (XRD) thin films revealed that the undoped and doped Y2O3 were amorphous with a broad hump around 27o and narrow humps around 48o and 62o for all samples. Except for the Y2O3:6wt.%CeO2 thin film, all had signal preferential orientation along the (100) plane at 2θ=12.71o which belongs to CeO2, Field emission scanning electron microscopic (FE-SEM) images confirmed the formation of the nanosized particles which resembles circles and others revealed rods and balls shape. UV-Vis spectra study showed peak absorption at a wavelength of 305 nm, with blue shift due to quantum confinement, and this also happened for the doped films, with direct energy band gaps. The photoluminescence spectra (PL) of undoped Y2O3 and doped thin films showed an emission peak at 365 nm at the same wavelength of all the prepared samples with a slight difference. All prepared films show three activation energies except Y2O3:6wt.%CeO2 film has two activation energies. From I-V characteristic curves, the prepared films have Schottky behavior except Y2O3:6wt.%CeO2 film, which displayed ohmic behavior. Y2O3:6wt.%CeO2 fabricated device revealed good photosensitivity for VIS and IR wavelength.

Микросферы из оксида иттрия для ядерной медицины

Cancers of liver are a problem of modern medicine. A common method of treatment is surgery. In patients who do not need surgery, various methods of local exposure can be prescribed (radiofrequency ablation, chemoembolization, brachytherapy, etc.). In the last decade, a method of treating cancer of liver — radioembolization of the liver-has been introduced into practice. The method is based on selective intra-arterial injection of glass or rubber microspheres containing yttrium radionuclide, resulting in local radiation exposure to tumor tissue. Recently, there has been increasing interest in the production of ceramic microspheres of the yttrium-90 (90Y) isotope. Narrow-fraction microspheres of pure yttrium oxide were obtained as a result of processing yttrium oxide powder in an air RF plasma. The resulting microspheres were subjected to ultrasonic treatment in deionized water, as a result of which the total specific surface area of the particles decreased by 10 %. Yttrium oxide microspheres were etched in a solution of sodium chloride for 11 days, after which the surface of the particles did not undergo significant changes. As a result, microspheres were obtained that have potential applications in nuclear medicine.

Optical and structural properties of arc melted Ce or Pr –doped Y2O3 transparent ceramics

This article presents the influence of praseodymium or cerium ions on physicochemical properties of yttrium oxide. Pure yttrium oxide and yttrium oxide doped with Ce or Pr ions powders were obtained by arc plasma synthesis. As a result of arc plasma synthesis, transparent, dense, uniform samples were obtained. To examine the microstructure and morphology of the powders and samples X-ray diffraction and scanning electron microscopy were used. X-ray studies have shown the incorporation of additives in the crystal lattice of yttrium oxide. In the present research work, Raman and FT-IR spectra of arc melted Ce or Pr –doped Y2O3 ceramics were reported. The optical and optical-magnetic properties were investigated for application as an optical insulator. Optical properties of the bulk samples were conducted from 200 to 1100nm. The in-line transmittances of ceramics exceed 35% from the visible band to the near infrared band. The results of measuring Faraday effect indicated that additives significance improve Verdet constant (> 130°/Tcm).

Synthesis and characterization of Yb doped Y2O3 nanopowder for transparent laser host ceramic materials

Pure yttrium oxide (Y2O3) and Yb doped Y2O3 (Yb: Y2O3) nanocrystalline powders were synthesized by the carbonate solution route which can be used in fabrication of transparent ceramics required for laser host application. Calcination time, temperature and pH were optimized to obtain well separated phase pure nanoparticles. The effect of Yb doping on structure of Y2O3 were studied by X-ray diffraction, transmission electron microscopy (TEM) and Raman spectroscopy. The phase structure was identified to be BCC for Y2O3 and distorted BCC for Yb: Y2O3 samples for 8 mole% doping of Yb. A decrease in lattice volume and homogeneous strain due to decrease in particle size was found to appear with Yb doping. Selected area electron diffraction (SAED) and High Resolution TEM (HRTEM) measurements investigations confirmed the BCC structure and found the nanoparticles to be in the range of 65-80 nm which decreased on Yb substitution. The Raman spectra explain the structural changes due to doping of Yb in Y2O3.

Synthesis characterization and luminescence studies of 100 MeV Si8+ ion irradiated sol gel derived nanocrystalline Y2O3

Nanoparticles of pure yttrium oxide (Y2O3) have been prepared by sol gel method. The powder X-ray diffraction (PXRD) pattern of as synthesized sample showed the amorphous nature. The as synthesized Y2O3 powders are annealed at 500, 600, 700, 800 and 900°C for 2h. Y2O3 powder heat treated for 600°C showed cubic phase and the crystallite sizes are found to be ∼13nm. Fourier transformed infrared spectroscopy (FTIR) revealed absorption with peaks at 3434, 1724, 1525, 1400, 847, 562 and 465cm−1. Photoluminescence (PL) of 100MeV Si8+ ion irradiated samples shows emission with peaks at 417, 432, 465nm. It is found that PL intensity increases with increasing in ion fluence up to ∼3×1012ionscm−2 and then decreases with further increase in ion fluence. A well resolved thermoluminescence (TL) glow with peak at ∼430K (Tm1) and an unresolved TL glow with peak at ∼538 (Tm2), 584K (Tm3) are observed in ion irradiated samples.

Thermoluminescence of combustion synthesized yttrium oxide

Pure yttrium oxide (Y2O3) was prepared by solution combustion technique using disodium ethylene diamine tetra acetic acid (EDTA-Na2) as fuel at ~350°C. Powder X-ray diffraction (PXRD) pattern of Y2O3 revealed cubic crystalline structure with crystallite size in the range of 18–23nm. The scanning electron microscopy (SEM) indicated the foamy and fluffy nature of the sample. Fourier transformed infrared spectroscopy (FTIR) revealed four prominent absorption with peaks at 3395, 1433, 875 and 566cm−1. From the optical absorption studies the energy gap of the synthesized sample was found to be 5.72eV. Two well resolved thermoluminescence (TL) glows with peaks at 475 and 626K were observed in γ-irradiated Y2O3. The glow curves were analyzed and the average activation energy was found to be 0.505 and 0.977eV respectively.

Substitution of pure Y 2O 3 by a mixed concentrate of rare earth oxides (CRE 2O 3) as sintering additive of Si 3N 4: a comparative study of the mechanical properties

In this work the substitution of pure yttrium oxide (Y 2O 3) by a mixed concentrate of yttrium and rare earth oxides (CRE 2O 3), produced at FAENQUIL-DEMAR, as sinter additive in gas-pressure sintered Si 3N 4 ceramics has been investigated. CRE 2O 3 presented similar behavior compared to pure Y 2O 3 in relation to the sinterability, intergranular phases formed, microstructure and mechanical properties. As this alternative additive is obtained at a cost of only 20% than that of commercial Y 2O 3, CRE 2O 3 demonstrated great potential as additive in the sintering of Si 3N 4 ceramics.

Solvothermal method to obtain europium-doped yttrium oxide

Pure yttrium oxide or mixed with europium oxide (3at%) were treated in supercritical isopropanolic suspension at 500°C for 20h and filling degree of 50%. Products were supercritically dried and characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), infrared spectroscopy (IR) and luminescence spectroscopy (LS). Particle shape is irregular with an equivalent diameter of ca. 5μm. Cubic crystalline phase is mainly obtained and hydroxide ion in low concentration is detected by IR vibrational spectrum. Europium in this concentration does not extensively change such observed characteristics from the pure yttrium oxide. Luminescence spectra show that the doped product is a mixture of the two oxides added by oxyhydroxide impurities. Nevertheless, this precursor sample, after being heated at 900°C during 1h, has all characteristics, especially luminescent ones, of the P22 commercial phosphor.

Effect of dispersion of pure yttrium oxide on its pressing and sintering

The yttrium oxide powder has an aggregated structure: the aggregates consist of particles of different size. In order to break down the aggregation of crystals in the original Y2O3 it is sufficient to use shortterm grinding (6 h) with the wet method in a ball mill; this yields a powder with a high dispersion and excellent pressibility. Grinding yttrium oxide in a drum made from plastic with balls made from Y2O3 excludes material contamination, the balls are scarcely worn away during operation, and the grinding pick-up from the lining of the mill is slight.

Sintering and recrystallization of yttrium oxide

The sintering of pure yttrium oxide was studied in the range 1800–2100°C with a soak of up to 30 h. The kinetics of densification and grain growth were studied during sintering, and the corresponding activation energy levels were calculated.

Broad Emission and Excitation Bands in Y 2 O 3 and YVO 4

Pure yttrium oxide has three x‐ray‐excited emission bands in the blue‐u.v. region of the spectrum. Addition of thallium gives a broad emission peaking at about 580 nm with a decay time of less than 20 nanosec and Eu3+ emission in this matrix can be sensitized with thallium and bismuth absorption bands. On lowering the temperature from room to liquid N2 both and show new emissions as well as complex differences in the excitation spectra. The results in are discussed on the basis of bismuth occupying two centers in this matrix.

高純度酸化イットリウムの製造

高純度酸化イットリウムの製造

Thermal Conductivity, Diffusivity, and Expansion of Y2O3, Y3 Al5O12, and LaF3 in the Range 77°–300°K

The thermal conductivities of Y2O3, Y2O3:Nd3+, Y3Al5O12:Nd3+, and LaF3 have been measured from 77°–300°K by a steady-heat-flow method. The densities of these crystals and of LaF3:Nd3+ have been determined in the same temperature range, using x-ray methods. Using this information and specific heat data from a variety of sources, the thermal diffusivities of these materials have been calculated. Although the diffusivity of pure yttrium oxide is somewhat higher than that of pure yttrium aluminum garnet, introduction of about 1 mole % of neodymium into both these compounds leads to crystals with diffusivities approximating that of undoped YAG. The diffusivity of doped yttrium oxide and YAG (about 0.05–0.06 cm2/sec at room temperature) is about three times that found for undoped lanthanum fluoride. The relative ease with which heat may be removed from Nd-doped Y2O3 and YAG suggests their use in lasers to diminish time variations in the width of the beam.