Addition Of Ytterbium Research Articles

Effects of neodymium or ytterbium addition to CH3NH3PbI3 perovskite solar cells inserted with decaphenylcyclopentasilane

Perovskite solar cells have attained high photoconversion efficiencies by changing chemical compositions of the perovskites and layered structures of the devices. However, the perovskite compounds easily decompose in air atmosphere even at the room temperature, and the photovoltaic properties are degraded by the formed defects. The motivation of this work is to solve these instability problems, and the objective the present work is to improve the film quality of the perovskite compounds by introducing lanthanide elements and decaphenylcyclopentasilane (DPPS), which were expected to contribute to decrease of the defects by the passivation effects. Here, effects of neodymium trifluoride (NdF3) or ytterbium trifluoride (YbF3) addition to CH3NH3PbI3 perovskite solar cells inserted with DPPS were investigated. Introduction of NdF3 or YbF3 increased the lattice constants and promoted crystal growth of the perovskites, and surface treatment by DPPS suppressed the PbI2 formation as surface passivation. Combined additions of NdF3 or YbF3 and DPPS contributed to the improvement of both the conversion efficiencies of the present perovskite devices and the stabilities of the photovoltaic properties by inhibiting the decomposition.

Identification of the effect of strontium and ytterbium addition over magnesium zinc alloy during the drilling process with ARAS and WASPAS techniques

Magnesium (Mg) alloys are widely employed in aerospace and automotive applications owing to their beneficial attributes. Identifying proper process parameters is a critical choice to save costs and increase quality. This necessitates the classification of suitable process parameters in light of numerous competing considerations; hence it must be analyzed by means of the Multiple Criteria Decision Making (MCDM) techniques. This paper handles the MCDM issue using two different approaches namely, the ARAS (Additive Ratio ASsessment) and WASPAS (Weighted Aggregated Sum Product ASsessment). The experiments carried out in Mg Zn10 and adding of Strontium (Sr) and Ytterbium (Yb) were critically evaluated. The independent variable like spindle speed and feed rate were examined by varying the machining tool and coolant supplied. The effect of coated and uncoated carbide was studied with High-Speed Steel. The influence of coconut oil, liquid nitrogen, and vegetable oil over the process parameters was also studied. The responses like thrust force, torque, and surface roughness were studied over the three different materials by varying the numerical and categorical factors. The addition of Yb plays a beneficial effect on all three responses considered. The ideal combination was discovered using ARAS and WASPAS for concomitant reduction of all the considered responses, attained with a coated carbide tool with a spindle speed of 118 m/min. and a feed rate of 0.26 mm/rev. during coconut oil coolant supply over Mg Zn10 Sr2. The ARAS rankings align with the WASPAS rankings in 55.56% of cases, with the interesting observation that both the lower and higher orders are identical. The optimal process parameters for Mg Zn10 were identified as a cutting speed of 56 m/min. and a feed rate of 0.26 mm/rev., using a coated carbide tool and CO coolant. For Mg Zn10 Sr2 Yb2, the study found the optimal parameters to be a cutting speed of 118 m/min. and a feed rate of 0.62 mm/rev., with the use of uncoated carbide and CO coolant.

Radiopacity and physical properties evaluation of infiltrants with Barium and Ytterbium addition.

Radiopaque properties in the infiltrant should be interesting for clinicians to feel more confident to indicate this treatment. Thus, the aim of this study was to evaluate the effect of the incorporation of barium and ytterbium particles on the physical properties of resin infiltrants. Groups were divided according to the addition of ytterbium oxide (Y) alone (30 or 40%) or Y with barium (YB) (15/15% or 20/20% respectively) in the Icon commercial infiltrant and in the experimental infiltrant base. Digital radiography (n=5), Microradiography (n=5), Microtomography (n=3), degree of conversion (n=5), water sorption (n=16), solubility (n=16), contact angle (n=16), flexural strength (n=16), elastic modulus (n=16) and Energy dispersive X-ray Spectroscopy (n=10) were performed. Analyses were performed using the R program, with a significance level of 5%, and microradiography and Microtomography analyses were evaluated qualitatively. In groups with 30 or 40% of ytterbium, radiopacity was higher or equal to enamel. Microradiography and Microtomography appear to have more radiopacity in groups with 40% (Y). Among the groups with no particle addition, those of the experimental infiltrant presented a higher degree of conversion than those of Icon®. In most groups, there was solubility below the ISO-recommended levels. The addition of particles resulted in higher viscosity. Groups with Icon had higher flexural strength and elastic modulus than groups with experimental infiltrant. The addition of 40% (Y) improved polymerization, had low solubility, and had greater radiopacity than enamel, however negatively affected the viscosity increasing then. Experimental groups with the base showed a higher water sorption than Icon groups.

Downconversion mechanism in Er3+/Yb3+ codoped fluorotellurite glasses to enhance the efficiency of c-Si PV cells

Fluorotellurite glass codoped with erbium and ytterbium was elaborated through the melting-quenching route. Through the DSC and Raman measurements, the investigated glass samples presented high thermal stability and low phonon energy, respectively. By using the laser excitation at 488 nm, the downconversion mechanism in the Er3+/Yb3+ system was investigated and the energy transfers implicated in the emissions of erbium and ytterbium ions were discussed based on the different cross-relaxation processes. The addition of ytterbium resulted in an effective energy transfer from the excited 4S3/2/2H11/2 state of Er3+ ions to the emitting 2F5/2 state of Yb3+ ion, which considerably enhanced NIR emissions at 1000 nm and reduced experimental lifetimes of 4S3/2/2H11/2 states. Through luminescence decay analysis, the maximum values of quantum efficiency (ηQE) and energy transfer efficiency (ηET) were estimated as 61.2% and 161.2%, respectively. This result indicates that the proposed glasses can convert visible photons into NIR emissions at 1000 nm suitable to improve the spectral response of crystalline silicon PV cells.

Effects of trace ytterbium addition on microstructure, mechanical and thermal properties of hypoeutectic Al–5Ni alloy

Over the past decade, the cast aluminum alloys with excellent mechanical and conductivity properties have emerged as potential materials for thermal management. However, the traditional Al–Si based alloys are difficult to make significant breakthrough in conductivity performance. The hypoeutectic Al–5Ni alloy also possesses sound castability and is expected to be applied in thermal management applications. In this study, the effects of ytterbium (Yb element) at 0–0.5 wt% on the microstructures as well as the electrical/thermal conductivity and mechanical properties of the Al–5Ni alloy were systematically investigated. The experimental results indicate that the addition of Yb at a relatively low amount not only reduces the secondary dendrite arm spacing of the α-Al grains, but also modifies the morphology and distribution of eutectic boundary phase. Moreover, it is found that the dosage of Yb at 0.3 wt% in the Al–5Ni alloy can simultaneously improve the yield strength, ultimate tensile strength and electrical/thermal conductivity. The strengthening and toughening of the Al–5Ni alloy are mainly attributed to the decrease of secondary dendrite arm spacing and the improvement of eutectic phases. The transmission electron microscopy/selected area electron diffraction (TEM/SAED) analysis indicates that the ytterbium in Al–5Ni alloy will form Al3Yb phase, which mainly agglomerates in the Al3Ni phase region. This phase is helpful to decrease the solubility of impurity elements (e.g., Fe and Si) in the α-Al matrix, which is beneficial to electrical/thermal conductivity. The value of this study lays foundation for manufacturing Al–Ni alloys with high thermal conductivity and acceptable mechanical properties.

Oxidation Behavior of the Skutterudite Material Yb0.2Co4Sb12

The skutterudite materials belonging to the CoSb3 family are widely studied for thermoelectric applications. They are typically used under vacuum, but applications under oxidizing environments are increasingly considered. The addition of ytterbium is known to enhance the thermoelectric properties of CoSb3, but the corresponding impact on the oxidation behavior of the skutterudite material is barely explored. For that purpose, the present research describes the oxidation behavior of Yb0.2Co4Sb12 under a flow of air at 800 K for 15, 50, 100, and 1000 hours. The oxidation treatment induces the growth of a surface layer made of three oxides in various amounts as a function of the oxidation time. The spinel oxide CoSb2O4/CoO·Sb2O3 and CoSb2O6 are observed from 15 hours of oxidation, whereas Sb2O4 is formed only from 100 hours of treatment. To assess the impact of ytterbium, the oxidation behavior of Yb0.2Co4Sb12 is compared to that of CoSb3 oxidized in the same experimental conditions. The results show that the low amount of ytterbium promotes the oxidation reactions of the skutterudite material. Nonetheless, the impact on the degradation of the material remains acceptable to use Yb0.2Co4Sb12 for thermoelectric applications under oxidizing environments.

Effect of Yb on the Structure and Properties of an Electroconductive Al–Y–Sc Alloy

The influence of ytterbium addition on the phase composition, strengthening upon annealing before and after rolling, and on the electrical conductivity and mechanical properties of the Al–0.2% Y–0.2Sc alloy has been investigated in this work. A dispersed eutectic, in which particles of an intermetallic phase with a size of 100–250 nm are enriched in yttrium and ytterbium, has been revealed in the cast structure apart from the aluminum solid solution. The maximum strengthening of the ingot is achieved after the annealing at 300°C for 3 hours due to the precipitation of Al3M dispersoids. The annealing of deformed sheets at 300°C results in an increase in the hardness and yield strength, which is connected with the initiation of the process of the additional decomposition of the aluminum solid solution. This means that the addition of ytterbium stimulates the heterogeneous nucleation of Al3M dispersoids in the post-rolling annealing process. In this case, according to the international standard for the annealed copper, the electrical conductivity increases with increasing temperature and time of annealing from 54 to 54.9% and to 57.7% after annealing at 200°C and 300°C, respectively.

Effects of ytterbium addition and heat treatment on the mechanical properties and biocorrosion behaviors of Mg–Zn–Zr alloy

Abstract Mechanical properties and biocorrosion behaviors in simulated body fluid (SBF) of newly developed Mg–5.8 Zn–0.5 Zr–x Yb (ZK60–x Yb, x = 0, 1.0, 2.0 wt%) magnesium alloys in the solution-treated (T4) and artificially-aged (T6) conditions were investigated. The results of mechanical properties show that with Yb addition, the microhardness and the ultimate tensile strength (UTS) of the tested alloys are significantly increased despite a slight decrease in tensile elongation in both T4 and T6 conditions. Especially, after the T6 treatment, the microhardness and the UTS of the samples were further improved, which was mainly attributed to the precipitation strengthening. The biocorrosion behaviors of the tested alloys were studied using electrochemical examinations and immersion tests. The results indicate that the biocorrosion resistance of the tested alloys is significantly improved by Yb addition in both T4 and T6 conditions. Although the corrosion resistance was slightly deteriorated after T6 treatment, the aged ZK60–2.0 Yb alloy still exhibited a favorable corrosion behavior, which was mainly ascribed to the corrosion barrier effect of a more compact and uniform protective film induced by the dispersed nano-scale precipitates. Electrochemical measurements also confirmed these observations. Given the favorable comprehensive performance in mechanical and biocorrosion behaviors, the T6 treated ZK60–2.0 Yb alloy may be considered as a promising candidate for biomedical applications.

Hardness of chromium nitride thin films prepared with addition of ytterbium

In this work, Yb was added as a third element to CrN as a means of developing new hard coatings materials via solution hardening. Cr–Yb–N thin films were prepared on Si substrates by pulsed laser deposition with various Yb contents, and compositional analysis confirmed that these films contained the expected elements. Phase identification results showed that the Cr1−xYbxN thin films for x ≤ 0.23 consisted of YbN in CrN as a solid solution with B1-(Cr,Yb)N as the only phase. However, films having x values of 0.51 or 0.53 had a two phase structure comprising (Cr,Yb)N and YbN. The hardness of each Cr–Yb–N thin film was successfully improved compared to that of a pure CrN thin film.

Improvement of sol-gel prepared tungsten trioxide photoanodes upon doping with ytterbium

The development of efficient and stable photoelectrodes keeps on being critical in the implementation of practical water splitting devices. Sol-gel synthesized tungsten trioxide thin film electrodes modified with ytterbium have been prepared on conducting glass substrates. All the obtained electrodes were found to be composed of monoclinic WO3, which is the photoactive crystal phase of WO3 for water oxidation. The photoelectrochemical behavior of both WO3 and WO3:Yb nanostructured electrodes in 0.1 M HClO4 is apparently characterized by a low degree of recombination. Ytterbium addition to tungsten trioxide improves its photoelectrochemical response as larger photocurrents are obtained without a significant change of the onset potential. This behavior is attributed primarily to a surface effect rather than to bulk doping. The addition of H2O2 to the aqueous electrolyte gives rise to both an increment in photocurrent and a shift of the photocurrent onset potential toward less positive values, which can be linked to the fact that hydrogen peroxide acts as an efficient hole scavenger. The implications of these findings in the mechanism of water photooxidation on WO3 are discussed.

Palladium-ytterbium bimetallic electrocatalysts supported on carbon black, titanium suboxide, or poly(diallyldimethylammonium chloride)-functionalized titanium suboxide towards methanol oxidation in alkaline media

Palladium-ytterbium (Pd-Yb) bimetallic catalysts with different Pd/Yb ratios supported on carbon black (20%Pd-x%Yb/C, x = 0, 1, 5, 10, and 15) were prepared by a sodium borohydride reduction method. The 20%Pd-5%Yb/C catalyst exhibited the best electrocatalytic activity towards methanol oxidation in alkaline media. The improved electrocatalytic activity and stability of 20%Pd-5%Yb/C can be explained by a bi-functional mechanism. In addition, the higher content of metallic palladium caused by the addition of ytterbium also contributes to the better catalytic activity of the 20%Pd+5%Yb/C catalyst. In view of the good electrocatalytic performance of 20%Pd+5%Yb/C, the 20%Pd+5%Yb catalyst supported on titanium suboxide (20%Pd+5%Yb/Ti4O7) was prepared. However, the Pd-Yb particles supported on Ti4O7 were seriously agglomerated. To improve the dispersion status of alloy particles, the Ti4O7 was functionalized with poly(diallyldimethylammonium chloride) (Ti4O7-PDDA). Electrochemical characterizations showed that no matter Ti4O7 or Ti4O7-PDDA as supports, Pd-Yb catalysts exhibited better catalytic activity than 20%Pd-5%Yb/C. The improvement mainly results from the further increase of metallic Pd due to the presence of Ti4O7.

Solidification behavior, microstructure and silicon twinning of Al-10Si alloys with ytterbium addition

The solidification behavior, microstructure and silicon twinning of Al-10Si alloys with Yb addition were investigated by thermal analysis, optical microscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The results indicate that the nucleation temperature, minimum temperature, and growth temperature of Al-10Si alloys decrease with increasing Yb content. The cooling curves of the Yb-modified alloys exhibit marked recalescence. The recalescence of the modified alloy peaks at 2.3 °C when the Yb content is 0.7 wt%. The 3D morphologies of eutectic Si in Yb-modified alloys change from a coarse plate-like structure to a honeycomb structure with many fine fibrous structures. The Al-Si-Yb intermetallic compound is observed in the 1.0 wt% Yb-modified alloy. Meanwhile, XRD analysis and TEM results indicate that the average twin spacing in the Yb-modified alloys is 18–46.2 nm. The average twin spacing of eutectic Si decreases with increasing Yb content. When the Yb content in the modified alloy is increased to 0.7 wt%, the average twin spacing value of eutectic Si reaches to 18 nm, which promotes the formation of twins and refinement of eutectic Si.

Enhanced mid-infrared 2.7 μm luminescence in low hydroxide bismuth-germanate glass and optical fiber co-doped with Er3 +/Yb3 + ions

In this article, low hydroxide bismuth-germanate glasses doped with Er3+ and co-doped with Er3+/Yb3+ ions have been synthesized. The fabricated host was characterized by high thermal stability parameter (ΔT=125°C), high transmittance in mid-infrared region and low maximum phonon energy (724cm−1). In order to reduce OH− ions impact on the transmittance value at the band of 3.1μm, the modified synthesis process has been conducted in low vacuum conditions (50–70mbar). The wide transmittance window from 0.515 to 5.5μm has been determined in terms of optical parameters. Luminescent properties of Er3+ ions indicated increase of luminescence intensity at the wavelength of 2.7μm (4I11/2→4I13/2) under 980nm laser diode excitation resulting from OH− reduction. Simultaneously, the addition of ytterbium to glass system has increased emission intensity in mid-infrared band due to Yb3+→Er3+ energy transfer. According to mid-infrared luminescence measurements, molar ratio of co-dopants in developed glass matrix for the maximum emission intensity has been determined. Glass characterized by the highest mid-IR emission intensity has been used as the active core of produced optical fiber.

Microstructural and Optical Characterization of TiO<SUB>2</SUB> Doped with Ytterbium Synthesized by Sol–Gel and Solar Physical Vapor Deposition Process

Pure and ytterbium doped TiO2 nanopowders in anatase phase have been prepared by sol-gel method (SGM) and Solar Physical Vapour Deposition process (SPVD). The physico-chemical parameters of the nanopowders have been described based on the results of micro-structural characterization performed by X-ray diffractometry, scanning electron microscopy, atomic force microscopy, and nitrogen sorption measurements. Thus, final micro-structural properties of SGM and SPVD titania nanopowders have been compared in detail revealing significant changes in the structure and morphology of these two types of materials. Addition of ytterbium had no significant effect on above-mentioned properties, although it modifies significantly the optical properties of the investigated materials. The luminescent properties of developed material were found to be comparable to bulk oxide materials and better than these reported earlier for ytterbium doped titania. In particular it has been shown that the luminescence of SPVD nanopowders is significantly stronger than this of SGM samples.

INTERLABORATORY STUDY ON ILEAL DIGESTIBILITY IN RABBITS: THE EFFECT OF DIGESTA COLLECTION TIME AND A SIMPLIFICATION OF THE PROCEDURE

In four laboratories, a total of 52 adult rabbits were fitted with a single T glass cannula at terminal ileum. After surgery recovery, animals were fed ad libitum with the same batch of a diet labelled by the addition of ytterbium attached to fibre particles. The effect of time during the ileal digesta collection period (morning and evening) on ileal digesta composition and ileal digestibility of DM, CP, NDF and ADF was evaluated. Compared with the evening samples, the morning samples had higher content of ytterbium (+5%) and CP (+43%) but lower contents of NDF (-9%) and ADF (-11%). Consequently, ileal digestibility for DM, NDF and ADF resulted in higher figures when calculated from the morning samples as opposed to those from the evening samples. However, CP ileal digestibility results were just the opposite. When compared with the results obtained as a reference value from the 24-hour samples (a pool of collections obtained in the morning, evening and night), the data average from the morning and the evening samples did not differ significantly. Therefore, it is possible to reduce the number of collections and simplify ileal digesta sampling by avoiding night collections.

ChemInform Abstract: (+)-(18-Crown-6)-2,3,11,12-tetracarboxylic Acid and Its Ytterbium(III) Complex as Chiral NMR Discriminating Agents

The compound (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid (I) and its ytterbium(III) complex are evaluated as chiral NMR discriminating agents. The crown ether is a useful chiral discriminating agent for protonated amino acid esters, amines, and amino alcohols. The crown can also be used with neutral primary amines since amines are protonated through a neutralization reaction with a carboxylic acid moiety of the crown. Enantiodiscrimination with the crown is observed in methanol and acetonitrile. Addition of ytterbium(III) nitrate to crown−substrate mixtures causes upfield shifts in the NMR spectrum of the substrate and often enhances the enantiomeric discrimination. Evidence indicates that the ytterbium(III) bonds to the carboxylic acid moieties of the crown, but enhancements in enantiomeric discrimination result from either the different association constants of the enantiomers with the crown or diastereomeric nature of the resulting crown−substrate complexes. The ytterbium complex with the crown is ...

Intense green and red upconversion emissions from Ho 3+ in presence of Yb 3+ in Li:TeO 2 glass

Weak visible emission is observed at 545 nm and 660 nm on 976 nm excitation of Ho 3+ ions doped in tellurite glass. Addition of ytterbium to the doped glass causes a large increase in intensity of the green and the red emissions. In addition to these two new emissions of Ho 3+ one in the blue and the other in the NIR region are also observed. This increase in intensity is ascribed to energy transfer from ytterbium ions to holmium ions. Rate equation model has been proposed to study the upconversion emission and its dependence on pumping power. Possible upconversion mechanisms for these emissions are also discussed. Effect of changing the concentration of Yb 3+ on the emission intensity, lifetime and full width at half maximum (FWHM) in 5F 4( 5S 2) → 5I 8 transition of Ho 3+ in codoped sample has also been studied.

Microhardness of silicon layers grown by liquid phase epitaxy

The microhardness of silicon epilayers grown from Sn fluxes is found to be lower than that of the silicon substrates and to significantly depend on the crystallographic orientation of the substrates. The microhardness values follow a Gaussian distribution in all of the epilayers. Unintentional impurities are shown to have a significant effect on the microhardness of the epilayers. The addition of ytterbium to the high-temperature solution reduces the microhardness of the epilayers.

Application of electrochemical techniques to study the effect on the anticorrosive properties of the addition of ytterbium and erbium triflates as catalysts on a powder epoxy network

New low curing temperature epoxy powder coatings cured with o-tolylbiguanide and catalyzed by the use of erbium(III) and ytterbium(III) trifluoromethanesulfonates have been formulated. Their curing kinetics and anticorrosive properties have been studied and compared with a system commonly used in industry ( o-tolylbiguanide/epoxy resin). Three different tests for measuring anticorrosive properties (EIS, AC/DC/AC, and salt fog spray) have been used together with an adherence test, in order to establish the ideal system. Results show that a system using 1 phr of ytterbium triflate presents good anticorrosive properties. The technique AC/DC/AC has shown its ability to evaluate properly and much faster than other techniques the anticorrosive properties of powder coatings with similar results.

Enantiomeric discrimination in the NMR spectra of underivatized amino acids and α-methyl amino acids using (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid

The compound (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid ( I) is a useful chiral NMR discriminating agent for underivatized amino acids and α-methyl amino acids. The α-methyl amino acids, when mixed with I in methanol, are protonated through a reaction with a carboxylic moiety of I and associate with the crown ether. Amino acids such as tryptophan, valine, alanine, and phenylglycine can be solubilized at suitable concentrations in methanol through the addition of deuterium chloride. The NMR spectra of mixtures of these amino acids with I show enantiomeric discrimination. Addition of ytterbium(III)nitrate to crown-substrate mixtures causes only small shifts and no discernible enhancements in enantiomeric discrimination in the NMR spectra of the substrates.