Quenching mechanism of Er^3＋ emissions in Er^3＋-and Er^3＋/Yb^3＋-doped SrAl12O19 nanophosphors

Nanoscaled SrAl12O19:Er3+ and SrAl12O19:Yb3+,Er3+ phosphors were synthesized by a combustion method.The emission intensities of every sample were compared by a new method with the emission of codoped Gd3+ ions as a reference.Compared with their bulk material prepared by the solid-state reaction method,a higher Er3+ quenching concentration,as high as 20%,was observed in the nanoscaled phosphors for both visible(VIS) and near infrared(NIR) emissions.The higher quenching concentration in both VIS and NIR regions for nanoscaled samples are related to the structure characteristics of the nano particles.The influence of the introduction of Yb3+ ions on the emission spectra intensity was also investigated and discussed.     

Interphase boundary precipitation in a Ti-1.7 at. pct Er alloy

Microstructures in a Ti-1.7 at. pct Er alloy were studied in the arc-cast, rapidly solidified, and annealed conditions. Transmission electron microscopy (TEM) of the rapidly solidified materials revealed 3- to 20-nm-diameter precipitates that were distributed in regularly spaced, approximately planar sheets throughout equiaxed α Ti grains. The precipitate sheet morphology is similar to the interphase boundary carbide sheets that have been documented in many alloy steels. In addition, precipitate fibers with cross sections of approximately 5 nm and up to 500 nm in length were often found adjacent to particle sheets. Electron diffraction experiments showed that the structure and lattice spacings of the sheet and fibrous particles are consistent with elemental erbium. Subsequent annealing treatments resulted in the formation of a face-centered cubic allotrope of Er₂O₃. The present work describes the precipitate morphologies and crystallography and discusses the applicability of current ledge growth models of interphase boundary precipitation to titanium-erbium alloys.     

Luminescence of Er^3＋ in Oxyfluoride Transparent Glass-Ceramics

Erbium doped silicate, germanate, and tellurium-germanate oxyfluoride glasses were prepared in a bulk form. Through appropriate heat treatment of the as-prepared glasses, transparent glass-ceramics (TGCs) were obtained with the formation of β-PbF2∶Er3 nanocrystals in the glass matrix were confirmed by X-ray diffraction. Well-defined diffraction peaks were observed in the samples after heat-treatment. The average crystal diameter of these precipitated crystals from full-width at half-maximum (FWHM) of the diffraction peak was estimated to be between 8 and 13 nm. Optical absorption, photoluminescence, and upconversion luminescence were measured on as-prepared glass and glass-ceramics. Luminescence spectra in the TGC samples revealed well-resolved, sharp stark-splitting peaks, which indicates that a majority of Er3 ions has been incorporated into the crystalline phase of the nanocrystals. The intensity of the visible and near infrared luminescence mostly increases in TSG compared to that in the as-prepared glass. In 1.53 μm absorption and emission bands, the maximum absorption peak is blue-shifted from 1531 to 1507 nm, whereas the maximum emission peak is red-shifted from 1535 to 1543 nm in TGC, as compared with that in glass. The bandwidth at half-maximum (BWHM) of the emission band is significantly broader in TGC than in glass, which is beneficial to the erbium-doped fiber amplifier (EDFA). Upconversion luminescence was measured using 800 nm near-infrared light excitation. Drastically increased upconversion luminescence was observed from the TGC as compared to that from their corresponding as-prepared glasses. In addition to a strong green emission centered at 545 nm because of 4S3/2→4I15/2 transition and a weaker red emission centered at 662 nm because of 4F9/2→4I15/2 transition, generally seen from the Er3 doped glasses, two violet emissions centered at 410 nm because of 2H9/2→4I15/2 transition and centered at 379 nm because of 4G11/2→4I15/2 transition were also observed from the TGC. The increased luminescence was attributed to the decreased effective phonon energy and the increased energy transfer between the excited ions when Er3 ions were incorporated into the precipitated β-PbF2 nanocrystals. The results indicated two attractive spectroscopic properties of the Er3 doped TGC samples, compared to glass samples, namely a reduced multiphonon decay rate and a reduced inhomogeneous broadening. In addition, these oxyfluoride TGC materials were robust, easy and flexibile to process, and possible to be fabricated in the fiber form for device applications.     

Structural and optical properties of Er2O3 films

Stoichiometric and amorphous Er2O3 films were deposited on Si(001) substrates by radio frequency magnetron technique. Spectroscopic ellipsometry measurement showed that the refractive index of the Er2O3 film in wavelength region of 400-1000 nm was between 1.6-1.7. The reflectivity of the Er2O3 films decreased greatly with respect to that from the uncoated Si substrates. The absorption coefficient of the Er2O3 film indicated that it had an energy gap larger than 4.5 eV. The obtained characteristics indicated...     

金属镝、钬、铒蒸馏提纯效果的研究

本文研究了金属镝、钬、铒的真空蒸馏提纯效果。实验结果表明,通过真空蒸馏,金属镝、钬、铒中的气体杂质及蒸气压与基体相差较大的杂质可有效去除,去除率分别为：镝９１．４％ ,钬９４．２％ ,铒９２．９％ ;对蒸气压与基体相近的杂质元素基本无去除效果。     

Upconversion of Er^3＋ Ions in LiKGdF5 ： Er^3＋ , Dy^3＋ Single Crystal Produced by Infrared and Green Laser

The upconversion fluorescence of Er^3＋ ions in LiKGdF5 ： Er^3＋, Dy^3＋ single crystal was studied under 785, 514.5, and 980 nm laser excitation. With the laser excitation set at 785 nm, strong green （centered at 543 nm） upconversion emissions, as well as weak red （651 nm）, violet （406 nm）, and blue （470 nm） upconversion emissions were obtained. With 514.5 nm laser excitation, violet （406 nm） and blue （470 nm） upconversion emissions were observed. Under 980 nm laser excitation, strong green （543 nm） and weak red （651） emissions were also obtained. The laser power dependence of the upconverted emissions was investigated to understand the upconversion mechanism. The excited state absorption （ESA） and the energy transfer （ET） processes were discussed as the possible mechanisms for all upconversion emissions.     

Preparation and luminescent properties of CaF2:Ln3+ (Ln:Er,Er/Yb)/Nafion composite films

In this work, CaF_2:Ln~(3+)(Ln:Er,Er/Yb)/Nafion composite films were prepared using Nafion as modifications and matrices by dripping method. The composite films were characterized by Fourier transform infrared spectroscopy(FT-IR), X-ray diffraction(XRD) and scanning electron microscopy(SEM). Composite films are transparent and CaF_2:Ln~(3+)(Ln:Er,Er/Yb) nanoparticles are well dispersed in Nafion films.The thicknesses of CaF_2:Er~(3+)/Nafion and CaF_2:Er~(3+),Yb~(3+)/Nafion composite film are about 77 and 73 μm,respectively. The nanoparticles in composite film possess cubic phase. CaF_2:Er~(3+),Yb~(3+)/Nafion composite film has stronger characteristic emission of Er~(3+) around 1530 nm with full width at half-maximum(FWHM) of 73 nm and longer luminescence lifetimes of 22.04 μs(25.03%) and 100.77 μs(74.97%).