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Abstract

Y2O3:Er3+ translucent ceramics was fabricated with addition of La(OH)3 nanopowder as a sintering aid. The influence of La(OH)3 addition on the microstructure, transmittance and upconversion luminescence of Y2O3:Er3+ ceramics was investigated in detail. The results show that the ceramics sample with 5 mol % La(OH)3 additives exhibits finer microstructure with fewer pores and higher optical transmittance than others. It was proved that La(OH)3 additives could greatly reduce the porosity and improve the transparency of Y2O3:Er3+ ceramics. By using a 980 nm diode laser as a pumping source, the Y2O3:Er3+ ceramics gave bright visible upconversion luminescence, which was ascribed to the radiative transitions of 2H11/2,4S3/24I15/2 and 4F9/24I15/2 of Er3+ ions, respectively. The possible upconversion mechanism has been proposed accordingly.

Abstract

ZrO2-Y2O3-Al2O3 nanocrystalline powders with different grain sizes have been synthesized using a chemical coprecipitation method. Nano-powders were compacted uniaxially and densified in a vacuum hot-pressing furnace. Density, pore size distribution, grain size and composition of the composites were determined by various techniques, including BET gas absorption, field-emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). It has been shown that the porosity, grain and pore size of the ceramics can be controlled by the initial powder size and sintering temperature. Fully densified ceramics with narrow grain size distribution in the range of 100 ∼ 500 nm could be obtained.

Abstract

Electroluminescence of Y2O3:Eu and Y2O3:Sm films, as well as the films coactivated with Eu and Sm, is studied. The electroluminescence spectra are measured. The physical mechanism of electroluminescence is analyzed It is shown that the increase in the heat treatment temperature and the content of doping impurities of the films enhances the intensity of electroluminescence. Additional doping of Y2O3:EuF3 films by the SmF3 impurity, practically does not influence the emission spectrum.

Abstract

In the present work we present preliminary research on producing of transparent polycrystalline ceramics. Samarium doped Yttrium oxide (1%, 3% and 5%) and Neodymium (1%) doped YAG (Y3Al5O12) translucent ceramics were fabricated by solid-state reaction. Commercial nanopowders was used as the starting materials: Sm2O3 (6μm) and Y2O2 (20-50 nm) for Sm3+: Y2O3 and α-Al2O3, Y2O3 and Nd2O3 (20-50 nm) for Nd3+: YAG. For the preparation of Nd3+: YAG, 0.5 wt% tetraethyl orthosilicate (TEOS) was use as sintering additive, and 1 wt % PEG (polyethylene glycol-400) as dispersant.

. 283-287, 1306-1310. 5. Kim J. S. (2002), Effect of alloying elements on the contact resistance and the passivation behaviour of stainless steels, Corrosion Science, No. 44, 635-655. 6. Oksiuta Z. (2011), Microstructural changes of ODS ferritic steel powder during mechanical alloying, Acta Mechanica et Automatica, Vol. 5, No. 2, 74-78. 7. Oksiuta Z. et al. (2011), Influence of Y2O3 and Fe2Y additions on the formation of nano-scale oxide particles and the mechanical properties of an ODS RAF steel, Fusion Engineering and Design, No. 86, 2417-2420. 8. Ollivier-Leduc A

Abstract

Neutron activation analysis of the Pleurotus ostreatus showed that adding of solid solution of ZrO2-Y2O3 hydroxide and oxide (3 mol % Y2O3) nanoparticles of size 4 and 9 nm at a concentration of 0.2 weight percent in a nutrient medium (Czapek) alters the character of physiological processes in the biological tissues of the mushrooms. This is manifested in the form of a significant change in morphological and physiological characteristics of the mushrooms and the elemental composition of the dry biomass. In particular, it is shown that the intercalation of nanoparticles into the tissues of the mushrooms leads to an increase of 1.3-1.4 times (more than 2.6 g/dm3) of biomass accumulation (industrial strain HK 35) and decrease of 1.7-1.8 times (below 1.7-2.5 mg/mm3) of concentrations of extracellular proteins into the culture fluid at a substantially constant value of the acidity. It is shown that the addition of ZrO2+3 mol % Y2O3 nanoparticles of sizes 4 or 9 nm into tissue of mushroom at step of the mother mycelium in very small concentrations can alter effectively the chemical composition of the substances produced by the cells and consequently, its physiological activity. It is shown that the use of low concentrations of ZrO2 nanoparticles allow to increase the yield and resistance of crops to diseases up to 1.2-1.5 times, as well as in the long term can be used in biomedical technologies for the treatment of cancer diseases.

Abstract

In this work, the molten salt synthesis technique was applied to the synthesis of YAlO3 powder using LiCl, NaCl or KCl salt as the flux. YAlO3 powder was synthesized by reacting equimolar amounts of Y2O3 and Al2O3 powders in LiCl salt. The synthesis temperature for YAlO3 using LiCl salt was 1300 °C which is by about 500 °C lower than that in the conventional mixed-oxide method. The synthesized powders have been characterized using powder X-ray diffraction (XRD) analysis and field emission scanning electron microscopy (FE-SEM). The effect of the salt type on the formation of YAlO3 has also been investigated.

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