Luminescence Properties Of Y2O3 Research Articles

Luminescent properties of praseodymium doped Y2O3 and LaAlO3 nanocrystallites and polymer composites

Luminescent properties of Y2O3 and LaAlO3 nanopowders doped with Pr3+ ions and PMMA-based composite materials doped with these powders were reported. The set of active nanopowders differing in praseodymium ions concentration was prepared using sol-gel method and carefully characterized with respect to emission properties in the visible spectral range. In particular, the excitation and emission spectra were measured together with fluorescence decay profiles and the differences between optical properties of these materials were discussed and compared with data available for bulk materials. Finally, the PMMA-based composite materials doped with Pr3+:Y2O3 and Pr3+:LaAlO3 nanopowders were manufactured and characterized. The obtained results showed that polymer composites doped with active nanopowders in general tended to keep the luminescent properties of the original nanopowders.

Preparation and luminescence properties of Y2O3:Er3+/TiO2 with high specific surface area

The three composites Y2O3:Er3+, Y2O3:Er3+/Yb3+ and Y2O3:Er3+/TiO2 were prepared using coprecipitation and sol-gel techniques. Their morphology, specific surface area, porosity, UV-vis. absorption spectra and fluorescence spectra were measured using SEM, TEM, surface analysis, UV-vis. absorption and photoluminescence spectrophotometry. SEM and TEM showed that samples prepared using coprecipitation were dispersed, while Y2O3:Er3+/TiO2 particles possessed a mesoporous surface and average diameter of about 10 nm. The specific surface area and porosity of Y2O3:Er3+/TiO2 did not result from the combination of the individual properties of Y2O3:Er3+ and TiO2. The specific surface area of Y2O3:Er3+/TiO2 was 135.991 m2/g and was 4.8 times that of Y2O3:Er3+ and 2.5 times that of Degussa P25 TiO2. A high specific surface area is conducive for application to TiO2 photocatalysis. The fluorescence spectra of the three composites exhibited three upconversion emission peaks with maxima at 237, 395 and 467 nm following excitation at 388, 500 and 570 nm, respectively.

Critical view on luminescence properties of Y2O3:Eu3+ after dispersion in SiO2

Improvement of luminescence intensity of material by core–shell formation or dispersion in another matrix was reported in literature. In this direction, we have prepared Y2O3:Eu3+ particles dispersed in SiO2. However, their luminescence intensities are less than Y2O3:Eu3+ due to non-radiative process arising from association of amorphous silica and Si–O–H. Variation of luminescence intensity is described in terms of site symmetry, heat-treatment effect and surrounding medium. Intensity of electric dipole transition is more than that of magnetic dipole transition for samples heated up to 1100°C. For higher heated sample at 1300°C, the opposite effect is found. This is explained on the formation of new triclinic phase α-Y2Si2O7.

Effect of solvent on the up- and downconversion emissions of Y_2O_3:Yb^3+−Er^3+ nanofibers synthesized by a hydrothermal method

We report on the structural, morphological, and luminescent properties of Y2O3:Yb3+ (2%)–Er3+ (1%) nanofibers synthesized by a hydrothermal method as a function of the solvent composition ethanol/water. The average length and diameter of the nanofibers ranges from 1.1 to 2.3 μm, and from 50 to 110 nm, respectively. A cubic crystalline structure was obtained, and no effect of the solvent was observed. However, the increment of OHs, because of the increment of water, modifies the quality of the nanofibers. Such impurities improve the emission bands under 940 and 490 nm excitation, especially the red band, via multiphonon relaxation. Relaxation dynamics is explained, based on direct and back energy transfer, multiphonon relaxation, and cross-relaxation. The direct energy transfer coefficients (Cb2, Cb4, and Cb5) calculated by the proposed theoretical model point out the fact that upconverted emissions are notably favored by the increment of OHs. The energy backtransfer (C5b) and cross-relaxation (C51) coefficients depend only on the ion concentration and not on the OH content.

SiO2包覆Y2O3∶Er3+纳米粉的制备及发光性能

SiO₂包覆Y₂O₃∶Er³⁺纳米粉的制备及发光性能

Luminescent properties of codoping Y2O3: Eu, Me (Me = Mg, Ca) nanorods

Phosphors of nanorods Y2O3: Eu (Mg, Ca) have been prepared by the hydrothermal method. The effect of Mg, Ca co-dopants on the Y2O3: Eu phosphor photoluminescence (PL) property was investigated. Upon excitation with ultraviolet (UV) irradiation, it is shown that there is a strong emission at around 610 nm corresponding to the forced electric dipole 5D0–7F2 transition of Eu3+. At a certain concentration, Mg, Ca ions’ doping effectively enhanced the luminescent properties of Y2O3: Eu3+ nanorods and did not change the cubic phase of the host. The structure of Y2O3: Eu3+ (Mg, Ca) phosphors was characterized by X-Ray diffraction (XRD). From XRD patterns, it is indicated that the phosphor Y2O3:(Eu, Ca) forms without impurity phase. From SEM, TEM images, it is shown that the crystal size of the nanorods phosphors is about 1–2 μm in length and 30–50 nm in diameter.

HIGH YIELD NANOPARTICLES SYNTHESIS OF EUROPIUM-DOPED YTTRIUM OXIDE RED-PHOSPHOR USING AN ORGANIC COMPOUND

This paper reports an approach for enhancing the luminescent properties of Y2O3:Eu3+ nanophosphors with cellulose, using a liquid phase precursor (LPP) process. The nanosized [Formula: see text] particles showed a powder X-ray diffraction pattern, corresponding to the reference, and were highly crystalline. The grain sizes of the samples synthesized at 600°C for 1 h were estimated to be approximately 19 nm. The particle sizes of the samples increased with increasing synthesis temperature and the morphology was cleaned and without impurities. In addition, all the samples had a smaller particle size than that of the commercial product. The PL spectrum consisted of weak bands at 581, 587, 593, and 599 nm, corresponding to the 5 D 0 → 7 F 1 transition, and sharp peaks with a maximum intensity occurring at approximately 610 nm, due to the 5 D 0 → 7 F 2 transition of Eu 3+. These results suggest that Y 2 O 3: Eu 3+ is a promising alternative red-emitting phosphor for high efficiency resolution display applications.