Papers by Keyword: Erbium

Abstract: Relevance of the work caused by necessity of expanding the database of the mutual solubility of salts of rare earth elements to create technologies for producing them in pure form for high-tech industries. The main aim of the study: was to investigate reciprocal solubility of lanthanum and erbium bromates and trichloroacetates in the water and the and to determine the conditions of solid solutions formation and the possibility of obtaining concentrates of lanthanum and erbium.

Abstract: This study investigated the fatigue crack propagation of Al–Mg–Mn–Zr alloys with erbium. The research found that in this alloy the crack propagation path prefers to extend along the grain boundary. If there are too many second phases or impurities in the gain boundary, the crack propagation will be influenced. The dispersed Al₃(Er, Zr) precipitate in the alloy can act as a core of heterogeneous nucleation to attract Mg, Zn and Al element, and reduce the large brittle Al₃Mg₂ second phase appear on the grain boundary, so the fatigue crack propagation rate can be slow down. In addition, these Al₃(Er, Zr) precipitate can pin the dislocation in the alloy to reduce stress concentration at the grain boundary, so it also has some positive effect to the fatigue crack propagation.

Abstract: This paper reports on the fabrication and optical characteristics of erbium-doped silica/PVA nanofibers via sol gel and electrospinning techniques. Silica glass, PVA (polyvinyl alcohol) and SiO₂/PVA composites displayed 85% to 90% transparent across 300 2000 nm wavelength range. The transmission spectra were measured using Cary 5000 UV-Vis-NIR spectrophotometer. Silica was synthesized using TEOS (tetraethylorthosilicate) as the precursor, while PVA solution comprised of 7.0 wt% in H₂O. The compositional ratios of SiO₂:PVA were from 6:4 to 1:9 and were doped with 0.2% to 0.6% of erbium. Suitable viscosities of Er³⁺-doped SiO₂:PVA solutions were electrospun into mesh of long strands nanofibers. Morphological and material compositions in the nanofibers were analysed using FESEM (field-emission scanning electron microscopy) and EDX (energy-dispersive X-ray spectroscopy). Er³⁺-doped SiO₂:PVA thin films were coated on fused-silica glass substrates via spin coating and were characterized for their refractive indices, optical transmission, and fluorescence using M-line technique, UV-Vis-NIR spectrometer and photoluminescence spectrophotometer, respectively. Lower ratios of silica to PVA solutions results in higher viscosities and produced more uniform nanofiber structures of diameters around 100 nm with lesser beads. The refractive index of 1.61 for Er-doped SiO₂:PVA (1:9) thin film was measured with TE polarized 632.8 nm wavelength laser and the index shows to be higher for more content of PVA in the glass/polymer composites. The 0.4% of Er³⁺ in SiO₂:PVA composite produced the highest luminescence intensity at 605 nm when excited with 514 nm source. Higher doping content caused ion clustering effect and leads to concentration quenching, hence decreased in the emission intensity.

Abstract: The high temperature strength of aluminum can be improved by forming thermal stable precipitates of microalloying elements such as Er, Sc and Zr. Our previous research indicates that composite addition of Er and Zr can improve the amount of precipitations, but the aging time to approach the peak hardness is relatively long. In this paper, we will focus on the deformation behavior of the Al-Er-Zr alloy during hot deformation process and the corresponding microstructure evolution. The results show that the strain can induce rapid precipitation in Al-Er-Zr alloy during hot working conditions. The mechanism of the rapid precipitation and its effect on thermomechanical processing are discussed.

Abstract: Improving the optical behavior of tellurite glass with controlled rare earth doping is an important issue from device perspectives. The Er³⁺ -doped tellurite glasses having composition (75-x)TeO₂-20ZnO-5Na₂O-xEr₂O₃ where (0 x 0.7) mol% are prepared by melt quenching technique and their structural and optical properties are investigated. Amorphous nature of the samples is confirmed through X-ray diffraction technique. The optical absorption recorded at room temperature in the wavelength range from 400 to 1000 nm exhibits five broad bands. The value of the optical band gap and the Urbach energy (ΔE) are calculated from the absorption edge data. The value of optical band gap lies between 2.18 eV and 2.89 eV for the indirect transition whereas the value of Urbach energy varies from 0.15 to 0.53 eV. The optical band gap and Urbach energy values are found to dependent strongly on the erbium concentration.

Abstract: The optical properties of porous silicon (PS) doped Erbium (Er) for different amount of Er was investigated.Porous silicon was prepared using electrochemical etching on p-type Si.The weight of Er varies from 0.01g, 0.02, 0.03g and 0.04g and was doped using thermal diffusion technique. Sample was annealed for one hour at temperature of 300^oC for diffusion using chemical vapour deposition (CVD).Photoluminescence spectroscopy analysis was performed to investigate the PL properties on PS doped Er. The physical properties of Er doped PS was investigated by Fourier Transform Infrared (FTIR) spectroscopy. The PL results shows that for 0.02g weight of Er doped on PS has the highest peak intensity and quenching effect observed at amount of Er higher than 0.02g doped on PS. From the FTIR analysis shows the existence of Er-O bonding as the impurity molecule which suggests that Er successfully doped onto PS.

Abstract: Different laser designs may require high-concentration erbium lasers. The laser efficiency can be measured by the small signal gain (SSG) of the laser media. In this paper an investigation of the SSG for a Er:YLF with 40 mol % of erbium concentration were carried out by means of computational simulation considering several pumping rates and different pulse duration . Results showed that the maximum SSG values for 40% Er concentration are reached for lower pulse durations and high pumping rates. In addition, results suggest that the performance of such lasers can be significantly enhanced by the adjustment of pulse duration and the interval between two consecutive pulses.

Abstract: Trivalent erbium ions, Er³⁺, in KY_1-xEr_xF₄ crystal produce up-converted photoluminescence (PL) band around 406 nm when excited by 488 or 532 nm photons. By using time-resolved spectroscopy, it was found that the up-conversion arises from the energy transfer processes between the excited Er³⁺ ions. Thermal behavior reveals that the 406 nm up-conversion is a phonon-assisted process. There is also a secondary up-conversion by level-crossing where a PL band around 520 nm is produced by the 532 nm excitation. High pressure causes the crystal to undergo a structural phase transition, as monitored by the PL it produces.

Abstract: The Ti/SnO₂-Sb electrode with/without Er were manufactured by Pechini’s method. The electrodes were characterized using SEM, EDS, XRD, FT-IR, the oxygen evolution potential test and their electro-catalytic abilities were evaluated though nitenpyram degradation. XRD and FT-IR results showed that the structure of the electrodes were Sn-base sosoloid without Er and Sb phases. The Er³⁺ iron entering the unit cell of SnO₂ (Sn⁴⁺) could cause the grain refinement, the surface enrichment of Sb and Er, stronger water absorbability, and higher anode potential. These consequently generated more active sites and less oxygen vacancies on the anode surface, leading the improving of the electro-catalytic performance. The grain refinement mechanism for Er doping may be ascribed to the increase of the surface composition supercooling, the acceleration of the SnO₂ generation rate, and the restrain of its growth rate.

Abstract: To increase efficiency of continuous 1.5 μm laser radiation crystal laser media should be used instead of the glass ones. Generation efficiency in major laser crystals with ytterbium and erbium is at a disadvantage in relation to phosphate glasses. A cause of this phenomenon is a reverse energy transfer. Could be found crystals comparable in efficiency with Yb-Er phosphate glasses At present a number of investigations on the use of ions relaxators Се 3+ in crystals Ca2Al2Si07 with ytterbium and erbium have been carried out to solve the problem of the reverse energy transfer in crystals [1,2]. It has been determined [1-3] that high content of cerium is needed to depress the reverse energy transfer. But cerium and ytterbium are in different ends of a lanthanide series, so silicate crystals with more isomorphic capacity such as Yb,Er,Ce:CaGdSiO (CGCS) have been proposed [3]. A sufficient solubility of Се 3+ ions in these crystals gives fast excitation relaxation on a laser level and guards against the reverse energy transfer from Er3+ to donor ions. Furthermore, a number of crystal media on the base of borate crystals with a developed phonon spectrum have been proposed [4,5]. They lack the reverse energy transfer, fast multiphonon nonradiative relaxation shunts the 4I11/2 – 4I13/2 Er3+ transfer. New crystals on the base of anhydrous borates – calcium-yttrium oxyorthoborates - Ca4YO(BO3)3 (YCOB) with ytterbium appeared recently [6], which showed high efficiency of generation, as well as calcium-barium fluor-orthoborates YbEr:Ca BaFBO3 (CBFB), in which ytterbium ions formed centers of luminescence with excellent characteristics [6]. Unfortunately, erbium ions in YCOB are characterized by high three level parameter [6], therefore the efficiency of generation Er,Yb:YCOB is not high. It has been determined recently that erbium ions in crystals CBFB have outstanding spectroscopic parameters, besides, between ytterbium and erbium ions fast energy transfer of electronic excitation takes place [7]. Since the efficiency of a sensitized laser medium depends on joint characteristics of the Yb and Er centres and the efficiency of their interactions, then available data allow considering crystals CBFB as a considerably promising matrix for an effective 1.5 μm laser. In order to obtain the most promising laser crystals and to answer the question cited above, it should be made their comparative analysis on basic spectroscopic and generative parameters. One of the important parameters related directly to the efficiency of the laser medium is an energy density of the generation threshold. Given spectroscopic parameters of active centers in crystals, the generation threshold of the one-activated laser medium (in an idealized model without passive losses) with a tree-level or quasi-four-level scheme of generation is specified by properties of active centers and can be easily determined by a simple formula [8]. The results obtained by this method are often used for determination of limiting parameters of the three-level laser media, the ytterbium media, for instance, and their comparative analysis [8]. There are known calculations of sensitized media generation parameters, among them the ytterbium-erbium glasses with a tube pumping [9], which although can be used for a diode pumping, nonetheless they are too unwieldy for simple estimation and comparative analysis. Hence there is a demand for simple analytical expressions such as [8] to calculate the lower limit of generation of the sensitized two-activated laser media with a diode pumping. The work reports the growing of single crystals CBFB and YCOB doped with erbium and ytterbium with erbium, and single crystals Yb,Er,Ce:CGS as well. We have made a comparative analysis of an ytterbium-erbium media for 1.5 μm lasers with a diode pumping on the base of simple expressions for limiting generation thresholds of the idealized sensitized media with a three-level scheme of generation, obtained in the approximation of balance equations without considering nonlinear and cumulative processes.