Increasing Yttrium Content Research Articles

Site-selective laser spectroscopy of mixed fluoride La1−x−yYxNdyF3 crystalline nanopowders

When replacing lanthanum with yttrium, mixed fluoride crystalline La1−x−yYxNdyF3 colloidal solutions and nanopowders (x = 0.1–0.3; y = 0.001, 0.01) demonstrate significant heterogeneity of the crystal structure. Therefore, the luminescence excitation and emission spectra of the Nd3+ ion are significantly inhomogeneously broadened. The spectral broadening increases with increasing yttrium concentration from 10 to 30 at.%. The measured luminescence band of Nd3+ ion with a maximum of approximately 862.5 nm includes the luminescence of three groups of optical centers OC1 − OC3. The luminescence of these OCs is quenched by OH− acceptors, which were embedded into the volume of nanoparticles (NPs) during the hydrothermal synthesis. Density functional calculations revealed three possible local positions of molecular OH− groups replacing fluorine ions. The observed difference in the luminescence quenching kinetics of the OC1 − OC3 centers is due to the different coordination of the local OH− groups around the Nd3+ ions.

Parameter optimization of ultrafine molybdenum powder during hydrogen reduction of MoO2 based on central composite design method

The hydrogen reduction of MoO2 is a common method for preparing ultrafine molybdenum powder, which is an important basic material for manufacturing high-performance Mo-based alloys. However, its preparation parameters are usually hard to be controlled. To address this issue, the work conducted the parameter optimization research during the hydrogen reduction process with using central composite design method, and the influence of different parameters such as reaction temperature, yttrium content, and hydrogen flow rate, on the particle size and oxygen content of the prepared molybdenum powder were investigated. The findings showed that the particle size of the prepared molybdenum powder is gradually decreased with the increase of reaction temperature and yttrium content, while gradually increased with the increase of hydrogen flow rate. The oxygen content of the prepared molybdenum powder is gradually decreased with the increase of reaction temperature and hydrogen flow rate, while gradually increased with the increase of yttrium content. Reaction temperature and yttrium content have significant interactions on the particle size and oxygen content are also concluded, and their respective regression model equations are obtained. The result also demonstrated that the particle size and oxygen content of the prepared molybdenum powder had a certain contradictory relationship. Through the comprehensive analysis, the optimal parameters for preparing ultrafine molybdenum powder with a low oxygen content are deduced, that is, reaction temperature: 1200 K, yttrium content: 0.1 mass%, and hydrogen flow rate: 1000 mL/min. Under the conditions, the average particle size and oxygen content of the prepared molybdenum powder are 320 nm and 0.456 mass%, respectively.

Synthesis and study of the properties of zirconium dioxide powders with different yttrium content

As part of the study, the influence of yttrium content on the properties of particles during controlled precipitation and after thermal treatment was investigated. Precipitation was carried out at a constant pH of 5 from nitric acid solutions, where the concentration of zirconium was 1 mole/dm3 and the yttrium content ranged from 0 to 30 % based on their oxides. The drying and calcination temperatures of the precipitates were 40 °C and 1000 °C, respectively. It was shown that with a yttrium content of up to 15 %, there was a consistent increase in the average diameter of zirconium hydroxide particles during deposition. When the yttrium concentration was increased to 30 %, the average particle size increased during the first 10 minutes of deposition, followed by a gradual decrease. The largest particle diameter was observed in the specimen with 7 % yttrium. In all cases, the formation of spherical aggregates was observed. With an increasing yttrium content, the boundaries between particles became smoother, and the degree of co-deposition of yttrium during synthesis decreased from 80 % to 60 %. Depending on the yttrium concentration, different modifications of stabilized zirconium dioxide powders were obtained: tetragonal ZrO2 for 2–7 % yttrium, and cubic ZrO2 for 15–30 % yttrium. Therefore, the results obtained during the study can be useful for the development of technology for the production of powdered materials for various applications.

Effects of yttrium on microstructures and properties of Cu45.12Zr45.12Al5.76Nb4 bulk metallic glass composites

The effects of yttrium on the microstructures and properties of Cu45.12Zr45.12Al5.76Nb4 bulk metallic glass composites were investigated. It was found that yttrium addition could effectively control the distribution and volume fraction of B2-CuZr precipitated phase in the composites by adjusting the glass-forming ability of the alloys, and suppress the eutectoid decomposition of B2-CuZr.Within 2 at.% yttrium addition, the volume fraction of B2-CuZr precipitation in the glassy matrix decreases significantly with the increase of yttrium content. For more than 2 at.% yttrium addition, the volume fraction of B2-CuZr precipitation increases as yttrium content increases. An optimal amount of yttrium (2–3 at.%) enhances glass-forming ability of the alloy, reduces B2-CuZr precipitation, and obviously improves the agglomeration and distribution uniformity of B2-CuZr in the amorphous matrix. The compressive properties of BMG composites with more than 1 at.% yttrium addition drop considerably, which should be mainly attributed to the abundant and various forms of Y2O3 brittle phase formed in the glassy matrix.

Structural and morphological studies on yttrium-doped magnesium aluminate spinel powders synthesized by mixed-fuel solution combustion synthesis approach

The incorporation of yttrium ions into the structure of magnesium aluminate spinel can be an effective approach to modify its microstructure, enhancing its formation, sintering behavior, and mechanical properties. In this work, a mixed-fuel solution combustion synthesis approach was used to prepare yttrium-doped spinel powders with the composition MgAl2-xYxO4 (x=0; 0.02; 0.06 and 0.10). It was shown that combustion of magnesium-, aluminum- and yttrium-nitrate salts solution in the presence of a mixture of specific fuels for each metal nitrate enables the direct production of crystalline spinels without the need for additional thermal treatment. Structural and morphological characterization showed that the main phase in all samples is a spinel phase (S.G. Fd3-m), while periclase (MgO), monoclinic yttrium aluminate (Y4Al2O9), and yttrium aluminum garnet (Y3Al5O12) were found in small portion in some samples. The average crystallite size increased in Y3+-substituted samples relative to undoped MgAl2O4, from 15 nm up to 40 nm. The lattice parameter increased with increase in yttrium content, ranging from 8.071 ? to 8.086 ?. The specific surface area of the synthesized powders spans from 8.2 m?/g for the undoped powder to 3.3 m?/g for the Y3+- substituted spinels with the maximum added yttrium content.

Enhancement of Piezoelectric Response in Yttrium Aluminum Nitride (YxAl1‐xN) Thin Films

Alloying rare earth elements into aluminum nitride (AlN) thin films to increase the piezoelectric response has gained a lot of attention in the past few years. Many rare earth elements are investigated in which scandium alloying resulted in the highest piezoelectric response for AlN. At the same time, researchers have also theoretically explored yttrium alloying as a feasible and economical alternative to scandium. Herein, for the first time, experimentally, the increase of the piezoelectric response of sputter‐deposited YxAl1–xN thin films as a function of increasing yttrium concentration as predicted by density functional theory calculations is demonstrated. Using differently manufactured targets, YxAl1–xN thin films with four different yttrium alloying concentrations (9, 12, 15, and 20 at%). are synthesized. Detailed thin‐film analysis is carried out and the highest value of d33 measured is 12 pC N−1 for Y0.2Al0.8N, which is a 250% increase compared to pure AlN. Even more, the Young's modulus decreases with increasing yttrium concentration in excellent agreement with theoretical predictions. Finally, Y0.15Al0.85N and Y0.2Al0.8N layers show high crystalline stability in pure oxygen environment up to 800 °C, demonstrating high oxidation resistance even under harsh environmental conditions.

Yttrium-substituted Co0.5Ni0.5YxFe2-xO4 ferrites as microwave absorbers by investigating structural, magnetic, dielectric, and absorption characteristics

The effect of Yttrium Substitution on Co0.5Ni0.5YxFe2- xO4 (0.0 ≤ x ≤ 1.0) Ferrites as Microwave Absorbers was investigated to include structural, magnetic, dielectric and X-band absorption properties. The main objective of this work is to enhance microwave absorption properties of materials with interesting dielectric/magnetic behaviors by doping rare earth element of Yttrium based on transition metals. The hydrothermal method was used to create Yttrium (Y) substituted nanoparticles, and the effects of Y-ion substitution on the characteristics, structural, magnetic features were examined by XRD, FT-IR, SEM-EDS, TEM-SAED, and VSM, respectively. Electromagnetic properties were obtained from microwave scattering parameters measured via a metal-backed transmission line and Nicholson-Ross Weir techniques using a vector network analyzer (VNA) in conjunction with an X-band waveguide set. Return loss (RL) values of the samples were obtained from the electromagnetic constitutive parameters (permittivity and permeability). According to the XRD measurements, hexagonal crystal structure of ferrite and YFeO3 as secondary phase nanocrystal sizes are between 11 and 67 nm. Refined structural parameters using Rietveld analysis are carried out using the TOPAS refinement program. A good match was observed between the diffraction patterns obtained and calculated by Rietveld analysis. Moreover, the morphological analyses indicate that the relatively small spherical structures of Ni-Co ferrites particles can be seen to change from spherical to hexagonal-shaped with increasing yttrium concentration. The results of the FT-IR study show that the spinel structure has formed as predicted because the expected range of absorption bands is present. According to magnetic measurements, the coercivity (Hc) results show a modest increase in porosity as the Y-content rises. The results revealed that the minimum RL value and bandwidth vary significantly with the amount of Yttrium in the mixture, indicating that the obtained structures will be useful for broadband microwave applications.

Sol-Gel Synthesis and Characterization of Yttrium-Doped MgFe2O4 Spinel.

In this study, an environmentally friendly sol-gel synthetic approach was used for the preparation of yttrium-doped MgFe2O4. Two series of compounds with different iron content were synthesized and A-site substitution effects were investigated. In the first series, the iron content was fixed and the charge balance was suggested to be compensated by a partial reduction of Fe3+ to Fe2+ or formation of interstitial O2- ions. For the second series of samples, the iron content was reduced in accordance with the substitution level to compensate for the excess of positive charge, which accumulates due to replacing divalent Mg2+ with trivalent Y3+ ions. Structural, morphological and magnetic properties were inspected. It was observed that single-phase compounds can only form when the substitution level reaches 20 mol% of Y3+ ions and iron content is reduced. The coercivity as well as saturation magnetization decreased with the increase in yttrium content. Mössbauer spectroscopy was used to investigate the iron content in both tetrahedral and octahedral positions.

Investigation on the gaseous hydrogen storage properties of as-cast Mg95-Al5Y (x = 0–5) alloys

The kinetics of hydrogen absorption/desorption of Mg-based materials are very sluggish and the thermodynamics of reaction is also poor. In order to improve the kinetics and thermodynamics of Mg-based materials, the Mg 95- x Al 5 Y x ( x = 0–5) composites were successfully prepared with the help of vacuum induction melting. Then, the isothermal hydrogen storage performances were researched by using Sievert apparatus and the non-isothermal hydrogen storage properties were measured by DSC (Differential scanning calorimetry) and TPD (Temperature programmed dehydrogenation). The phase components were determined by X-ray diffraction, and the observation of micromorphology and the determination of crystal state were completed by using SEM (Scanning electron microscope), TEM (Transmission electron microscope) and SAED (Selected area electron diffraction), respectively. According to the result, the substitution of Y for Mg results in the formation of the second phase Mg 24 Y 5 which transforms into the magnesium hydride and high thermal stability yttrium hydrides after hydrogenation. With the increase of Y content from 0 to 5, the absolute value of dehydrogenation activation energy E a de decreases from 155.562 ± 2.29 to 79.622 ± 5.61 kJ/mol. Considering the standard errors of fitting and measurement, the influence of Y substitution on the thermodynamics parameters is not obvious. However, the initial decomposition temperature of the Mg–Al-based alloy can be reduced by 40.2 K through the addition of yttrium. • The Mg 95- x Al 5 Y x ( x = 0–5) composites were prepared by induction melting. • The specimen Mg 90 Al 5 Y 5 has the minimum activation energy of 79.622 ± 5.61 kJ/mol. • The kinetics are ameliorated with the increase of yttrium content.

Effect of Yttrium on the microstructure, phase transformation and superelasticity of a Ti–Ni–Cu shape memory alloy

The purpose of this work is to systematically investigate the effect of substituting Yttrium for Ti on the microstructure, phase transformation and superelasticity of Ti50Ni44Cu6 alloys. The results show that a single-step martensitic transformation occurs in all the selected Ti–Ni–Cu–Y alloys. With increasing Yttrium content, the transformation temperatures first increase approximately by 10–15 °C and then decreases slowly. In the cyclic compression experiments of pre-strain from 2% to 10%, the main reason for the increase of the residual strain is the plastic deformation of the alloys caused by the increasing pre-strain. In the cyclic compression experiments of 5% fixed pre-strain, the recovery rate and the total recoverable strain can be effectively improved to 92.4–96.6% and 4.6–4.83%, respectively. With increasing cycles, as the formation of stress-induced martensite is precluded by high density dislocations, the superelasticity-dominated recovery transforms to elasticity-dominated recovery, which may lead to the gradual decrease of residual strain. In the two kinds of cyclic compression experiments, the results show that the alloys with higher Y content normally have better superelasticity.

Влияние иттрия на структурно-фазовое состояние in situ композита Mo – 15,3 V – 10,5 Si

The effect of yttrium on the structural-phase state of the Mo – 15.3 V – 10.5 Si hypereutectic alloy has been investigated using X-ray phase analysis and scanning electron microscopy with energy-dispersive X-ray analysis. It has been established that the main phases of Mo – (14.3 – 15.4) V – (9.8 – 10.6) Si – (0.3 – 5.3) Y alloys obtained under nonequilibrium crystallization are the metal solid solution (Mo1 – xVx)ss-matrix, silicide solid solution (Mo1 – xVx)3Si and silicide Y5Si3. In alloys doped with yttrium up to 1.0 at. %, the space between the dendrites of the (Mo1 – xVx)ss metal phase is filled with (Mo1 – xVx)3Si solid solution, and Y5Si3 is located at the boundaries of the metal solid solution. At a concentration of yttrium in alloys above 3.0 at. % the space between (Mo1 – xVx)ss dendrites is filled with Y5Si3 silicide, inside which (Mo1 – xVx)3Si grains are formed. Triple or quaternary compounds containing yttrium were not detected. Elemental composition of alloy phases of the Mo – (14.3 – 15.4) V – (9.8 – 10.6) Si – (0.3 – 5.3) Y alloys is almost identical and is characterized by non-stoichiometry with respect to silicon. According to well-known literature data, the silicon contents in the (Mo1 – xVx)ss and (Mo1 – xVx)3Si phases are within the acceptable limits of the homogeneity region, and the silicon concentration in Y5Si3 (≈ 35.4 at.%) is beyond the established limits. Doping of the Mo – 15.3 V – 10.5 Si alloy with yttrium increases the dispersion of the structure. Particles of the main structural components become close in size. Wherein the volume ratio of the metallic phase to the silicide with increasing yttrium content in the alloys increases. The density of alloys varies between 8.7 – 9.0 g/cm3.

Effects of Y doping on the magnetic properties and magnetocaloric effect of CeFe2

The magnetic properties and electronic structure of single phase cubic Laves Ce1−xYxFe2 compounds with x ≤ 0.25 are analysed by correlating magnetic measurements with band structure calculations. The Y substitution for Ce stabilizes a ferrimagnetic order in all investigated samples, as indicated by the increase of the spontaneous magnetization values with the decrease of Ce content. The band structure calculations yield negative magnetic moments for the Ce and Y atoms, hence an antiferromagnetic coupling to the Fe magnetic moments. All samples show a second order magnetic phase transition and a roughly linear increase of the transition Curie temperature with Y concentration from 247 K for x = 0.1 to 330 K for x = 0.25. The magnetocaloric effect around the magnetic transition temperature was also investigated and although the maximum value of the magnetic entropy change decreases with increasing yttrium content, large RCP(S) values were obtained for all samples due to the broad ∣ΔSm∣ peaks.

Characterization and photocatalytic activity of Y-doped BiFeO3 ceramics prepared by solid-state reaction method

Singe phase bismuth ferrite doped by yttrium (Bi1−xYxFeO3, x = 0, 0.05, 0.1, 0.15, 0.2 and 0.25) was synthesized by solid-state reaction followed by sintering. Their structural, morphological, ferroelectric, magnetic and optical properties were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), vibrating sample magnetometer (VSM) and UV–visible spectrophotometry. Rhombohedrally-distorted perovskite structure of bismuth ferrite was confirmed by XRD analysis and Rietveld refinement. Microstrain and crystallite size were analyzed using Williamson-Hall model. SEM micrographs showed agglomerated particles. The doping of yttrium into the BiFeO3 (BFO) lattice enhanced the ferroelectric and magnetic properties and the leakage current density was reduced. The energy band gap was also decreased by increasing yttrium content, leading to an enhancement of light absorption capability. The photocatalytic activity of all samples has been evaluated by the decolorization of methyl orange (MO) under visible light irradiation. The results indicated that increasing the concentration of yttrium into the BiFeO3 (BFO) structure improved the photodegradation up to 71%.

Differently shaped nanocrystalline (Fe, Y)3O4 and its adsorption efficiency toward inorganic arsenic species

Herein we report effects of partial substitution of Fe3+ by Y3+ in magnetite (Fe3O4) on morphology and inorganic arsenic species adsorption efficiency of the Fe3−xYxO4 nanoparticles formed. The series of Fe3−xYxO4 (x = 0.00, 0.042 and 0.084, labeled as Y00, Y05 and Y10, respectively) was synthesized using co-precipitation followed by microwave-hydrothermal treatment (MW) at 200 °C. With increase of yttrium content (x value), both the morphological inhomogeneity of the samples and the fraction of spinel nanorods as compared to spinel pseudospherical particles increased. By both transmission electron microscopy and x-ray powder diffraction analyses, it was determined that the direction of growth of the spinel nanorods is along the [110] crystallographic direction. The Fe3−xYxO4 affinities of adsorption toward the inorganic arsenic species, As(III) (arsenite, AsO33−) and As(V) (arsenate, AsO43−), were investigated. Increased Y3+ content related to changes in sample morphology was followed by a decrease of As(III) removal efficiency and vice versa for As(V). The increase in Y3+ content, in addition to increasing the adsorption capacity for As(V), significantly expanded the optimum pH range for the maximum removal and decreased the contact time for necessary 50% removal (t1/2) of As(V) (Y00: pH 2–3, t1/2 = 3.12 min; Y05: pH 2–6, t1/2 = 2.12 min and Y10: pH 2–10, t1/2 = 1.12 min). The results point to incorporation of Y3+ in the crystal lattice of magnetite, inducing nanorod spinel structure formation with significant changes in sorption properties important for the removal of inorganic arsenic from waters.

Microstructure characteristics, hydrogen storage kinetic and thermodynamic properties of Mg80–xNi20Yx (x = 0–7) alloys

Mg80–xNi20Yx (x = 0–7) alloys were successfully prepared by using the vacuum induction melting method. The structural characterizations of the alloys were performed by using X-ray diffraction, scanning electron microscope, transmission electron microscope and X-ray photoelectron spectroscopy measurements. The effects of yttrium content on the microstructure and hydrogen storage properties of the as-cast alloys were investigated. The alloys are composed of a primary phase of Mg2Ni, lamella eutectic composites of Mg + Mg2Ni, and some amount of YNi3. The YNi3 has completely transformed into in situ formed nanoscale YH2 and YH3, with the formation of Mg2NiH4. Pulverization of the alloy particles was observed during the hydrogen absorption and desorption cycles. However, the phase composition remains unchanged even after 20 hydrogenation cycles. Yttrium addition significantly improved the hydrogen-absorption kinetic performance of the alloy. In addition, pressure-composition-temperature measurements indicated that the entropy and enthalpy changes for the formation and decomposition of MgH2 and Mg2NiH4 gradually decreased with the increase of yttrium content.

Corrosion behavior of bulk (Zr58Nb3Cu16Ni13Al10)100-xYx (x = 0, 0.5, 2.5 at.%) metallic glasses in sulfuric acid

Bulk (Zr58Nb3Cu16Ni13Al10)100-xYx (x = 0, 0.5, 2.5 at.%) metallic glasses exhibited good passivation ability and outstanding corrosion resistance in de-aerated 0.5 mol/L H2SO4 solution. It was mainly beneficial from the stable passive film which mainly consisted of ZrO2 and Al2O3. However, the defects concentration in the passive films increased with the increasing yttrium content in the Zr-based BMGs. The yttrium additions improved the electrochemical homogeneities of the Zr-based BMGs, but facilitated the dissolution of Cu, resulting in a slight deterioration of corrosion resistance of the Zr-based BMGs.

Structure and conductivity in the Bi4Nb1−xYxO8.5−x oxide-ion conducting system

A study of structure and oxide-ion conductivity in the Bi4Nb1−xYxO8.5−x solid solution using X-ray and neutron powder diffraction and a.c. impedance spectroscopy is presented. Slow cooled samples are typically biphasic, exhibiting a mixture of cubic/pseudo-cubic and orthorhombic or tetragonal fluorite based phases. Single phase cubic and pseudo-cubic materials can be isolated by quenching from high temperatures. The defect structure in these quenched phases has been determined by neutron diffraction and shows an oxide-ion distribution that is compositionally dependent. This distribution is correlated with the compositional variation of the low temperature activation energy for total conductivity, whereas the activation energy for high temperature conductivity decreases with increasing value of x, reflecting the reduction in dopant-vacancy interaction with increasing yttrium content, as well as a change from a tetragonally ordered type III phase for low x-value compositions to a fully disordered δ-Bi2O3 type phase at x = 0.4. Ordering phenomena are proposed to account for the appearance of a linear intermediate temperature region with high activation energy in Arrhenius plots of conductivity at x ≥ 0.4. Conductivities in the order of 10−1 S cm−1 are achieved at 700 °C in these materials.

Experimental study of the effect of yttrium on the structural, thermal, and magnetic properties of BiFeO3

In this paper, structural, thermal, and magnetic properties of Bi1−xYxFeO3 (BYFO, x = 0, 0.05, 0.1, 0.15, 0.2, and 0.25) nanoceramics have been studied. We have synthesized BYFO nanoceramics using solid-state reaction method followed by sintering. X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and microstructural analysis showed that all as-prepared samples have a single-phase perovskite structure. Differential thermal analysis (DTA) indicated that TC (ferroelectric–paraelectric transition) is decreased with the addition of yttrium into the BFO structure. Magnetic properties of the samples were examined by vibrating sample magnetometer (VSM). We have observed the enhancement of magnetization by increasing yttrium content. Y-substitution decreased remanent magnetization (Mr) and increased the coercivity (Hc). A noticeable change in the magnetic hysteresis loop of Bi0.75Y0.25FeO3 can be triggered by an applied magnetic field and it confirmed the enhancement of magnetic properties.

Growth and optimized scintillation properties of Ce:Li6Lu1-xYx(BO3)3 mixed crystals

Ce:Li6Lu1-xYx(BO3)3 (x = 0.08, 0.2, 0.4, 0.6, 0.8) mixed crystals were grown by Czochralski method to optimize the scintillation properties of lithium rare earth borate crystals for thermal neutron detection. The crystal structure of the mixed compounds belonged to the monoclinic system with space group P21/c. Their density decreased with the increasing yttrium content from 3.44 to 2.77 g/cm3. Their degree of supercooling ranges from 135.3 to 119.2°. The X-ray induced luminescence spectra present a double peaked emission bands with a maximum at 380 and 410 nm corresponding to 5d1 to 2F5/2 and 2F7/2 transitions of Ce3+ ions. The photoluminescence decay times are below 36 ns. Ce:Li6Lu0.8Y0.2(BO3)3 had the best light output under the excitation of α particles and γ rays, and from that point of view is the most promising lithium rare earth borate fast scintillator for thermal neutron detection.

Synthesis and characterization of Co-Zn based spinel ferrites

Co-precipitation method was used to prepare spinel ferrites having composition Co0.6Zn0.4YxFe2−xO4, where x is 0.00, 0.025, 0.05, 0.075, and 0.10. The magnetic, dielectric and structural characteristics of all these prepared ferrites were determined. XRD (x-ray diffraction) results proved the cubic spinel structure of synthesized ferrites. The dielectric loss, dielectric constant and AC conductivity reduced by adding rare earth concentration. The role of grains and grain boundaries was studied by using impedance analysis. The resistance of grains and grain boundaries was measured from Cole-Cole plots. Soft nature of prepared ferrites was confirmed by magnetic characters. By increasing yttrium concentration, remanence and saturation magnetization were reduced while coercivity was increased. All these parameters suggest synthesized ferrites as the best candidate for high frequency applications.