Yttrium Molybdate Research Articles

Rational construction of dairy flower-like zinc oxide-doped yttrium molybdate for the electrochemical detection of uric acid

Rational construction of dairy flower-like zinc oxide-doped yttrium molybdate for the electrochemical detection of uric acid

Investigations of structure-improper ferroelectricity relationships to enhance the multifunctional applications of the β′-Y2(MoO4)3 phase

Polycrystalline samples of the compound Y2(MoO4)3 have been synthesized by solid-state reaction starting from the corresponding yttrium and molybdenum oxides, and the pure ferroelectric phase has been successfully isolated. Both β’ (ferroelectric) and β (paraelectric) phases were studied by conventional X-ray diffraction at different temperatures, performing the corresponding Rietveld refinements before and after the phase transition. An analysis of the displacive symmetry modes involved was carry out. The thermal dependence of the crystal structure was also studied, confirming that it is an improper ferroelectric with a primary order parameter that does not correspond to the spontaneous polarization. To corroborate the purity of the β′-phase, TG and SEM-EDX analyses were performed, demonstrating the absence of the γ-phase. Moreover, DSC analysis and impedance spectroscopy confirmed the Curie temperature of the β′-β phase transition (Tc around 378 ​K). Ferroelectric hysteresis cycles were recorded as a function of temperature and at different maximum applied electric fields. The values of the maximal and remanent polarization were correlated with the structural study. Finally, anomalies in the electrical permittivity and conductivity were observed between 600 and 877 ​K, which may be associated with the evolution of the lattice parameter c at high temperatures. With this ferroelectric characterization we want to highlight this still unexploited crystal matrix in comparison to other rare earth molybdates with the β′-phase and other yttrium molybdate compounds.

Application of yttrium molybdate tethered polypyrrole nanocomposite for the photocatalytic remediation of nitrofurantoin in water

The present work reveals the photocatalytic ability of yttrium molybdate coupled polypyrrole nanocomposite (YMoO4/PPy) towards the removal of nitrofuran-based broad-spectrum antibiotic nitrofurantoin (NFT) in water under the irradiation of light-emitting diode (LED). Here, YMoO4 was hydrothermally prepared while template-driven growth of PPy nanorods was employed and, finally, the preparation of composite (YMoO4/PPy) was facilitated by ultrasonication. The as-synthesized YMoO4/PPy was explored via electron-microscopy for morphology investigation, X-ray diffraction for structural characterization, Fourier-Transform infrared spectroscopy to confirm chemical functional entities, UV-Visible spectroscopy for determining the bandgap, and electrochemical investigations for photoelectrochemical characterization of the synthesized systems. The composites (1:1, 1:2, and 2:1 YMoO4/PPy by percentage weight) and the individual counter-parts (YMoO4 and PPy) were evaluated in a LED-aided photocatalytic system against NFT. It was observed that ∼93% of NFT (15 ppm) was mineralized within 80 minutes of reaction by a 1:2 YMoO4/PPy (25 mg) catalyst. The kinetics of response fitted the pseudo-first-order model with close to unity value of coefficient of determination. Here, the influence of conducting polymer is significant in terms of rapid electron mobility and prolonged charge separation. Also, the minimal blend of rare-earth oxide upholds the economy and real-time application. Therefore, the present work explicitly explored the combination of rare-earth metal oxide interfaced conductive polymer taking into account photo- and electro-intrinsic traits of the composite.

Solution Combustion Synthesis of Yttrium molybdate (Y6MoO12) Nanoparticles by using Peroxomolybdic Acid, Characterization and Applications

The main aim of our present research work is to synthesize the distinct yttrium molybdate (Y 6 MoO 12 ) nanoparticles with excellent photocatalytic activity through ultra-rapid solution combustion route using peroxomolybdic acid as molybdenum source for the first time. The morphology of Y 6 MoO 12 nanoparticles studied using scanning electron microscopy (SEM) exposes that the particles are exceedingly porous and agglomerated. From BET surface area measurement, it is examined that Y 6 MoO 12 nanoparticles exhibit relatively large surface area (40.34 m 2 g −1 ). The formation of pure crystalline Y 6 MoO 12 nanoparticles with cubic phase were analysed by the technique powder X-ray diffraction (PXRD). Transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and the selected area electron diffraction (SAED) patterns of the Y 6 MoO 12 nanoparticles described that, Y 6 MoO 12 nanoparticles consists of well-dispersed nearly spherical-shaped nanoparticles with the polycrystalline nature. The analysis of photocatalytic activity on Y 6 MoO 12 nanoparticles shows highest ( ∼ 85%) degradation of methylene blue (MB). The electrochemical studies using cyclic voltammetry reveal a substantial increase in current density of Y 6 MoO 12 electrode when compared with bare carbon electrode and the instantaneous rise in redox current for the Y 6 MoO 12 electrodes with increasing scan rate from 50 mVs -1 to 90 mVs -1 .

Fabrication of Y6MoO12 molybdate ceramics: From synthesis of cubic nano-powder to sintering

The family of cubic yttrium molybdate (Y6MoO12) has been chosen due to the possibility of substituting Y3+ cations by luminescent trivalent rare earth (RE3+) ones and to obtain transparent optical ceramics. The goal of the paper is to find a route towards the fabrication of dense Y6MoO12 ceramics from nano-powders and using well-known ceramic sintering techniques such as Spark Plasma Sintering (SPS) and Hot Isostatic Pressing (HIP). We have investigated in detail process of the powder preparation by a combustion method as well as the sintering processes taking into account all important sintering parameters. Evaporation of MoO3 was found to be correlated to reductive conditions or heating rate. Sintering was optimized in terms of phase composition, microstructure and porosity.

Термодинамическое моделирование процесса окисления доэвтектического сплава Moss-Mo3Si, легированного иттрием

In order to study the effect of yttrium additives on the oxidation of molybdenum silicide alloys, thermodynamic modeling of the interaction in the Mo-Mo3Si-Y5Si3 system with dry and moist air was performed in the temperature range 25-2000 °C. To predict the composition of oxidation products and the sequence of the formation of phase components, the dependences on the temperature and consumption of oxidants – water vapor and oxygen of the air – are obtained. The calculations were performed using the HSC Chemistry 6.12 software, into the database of which the calculated missing thermochemical characteristics of Y2Si2O7, Y2SiO5 silicates and yttrium molybdates Y2Mo3O12, Y2MoO6 were entered. It is shown that, under equilibrium conditions, the oxidation process with dry and moist air proceeds almost equally, since the interaction of the components of the alloy with oxygen is thermodynamically preferable than with water vapor. According to the obtained thermodynamic models, the oxidation process of the Mo-5 wt. % Si alloy of the hypoeutectic composition doped with yttrium can be represented as a sequence of the following chemical transformations: firstly Mo and Y silicides oxidize forming Y2O3, SiO2 and metallic Mo, then molybdenum is oxidized to MoO2 and Y2O3 interacts with SiO2 with the formation of silicates Y2SiO5 and Y2Si2O7. As a result of the complete oxidation of the alloy, MoO3 and Y2Mo3O12 are added to the condensed product, and molybdenum oxide (MoO3)n vapor appears in the gas phase. Based on the results of a complete thermodynamic analysis, the possibility of the formation of silicates and yttrium molybdate during the oxidation of the hypoeutectic alloy Mo-5Si-3Y (wt. %) was established. This can increase its oxidation resistance due to the formation of a protective film limiting the diffusion of oxygen into the alloy, which, of course, requires experimental confirmation.

Enhancing the upconversion luminescence properties of Er3+–Yb3+ doped yttrium molybdate through Mg2+ incorporation: effect of laser excitation power on temperature sensing and heat generation

Upconversion luminescence was enhanced by incorporating Mg2+ into Er3+–Yb3+-doped yttrium molybdate and the effect of laser excitation power on temperature sensing and nanoheating was investigated.

Rational construction of novel rose petals-like yttrium molybdate nanosheets: A Janus catalyst for the detection and degradation of cardioselective β-blocker agent acebutolol

Metal molybdates has paid emerging attention in variety of energy and environmental applications owing to their extra-ordinary physicochemical properties. In this regard, novel rose petal-like yttrium molybdate nanosheets (YMoO4; YM NSs) was successfully designed through a simple wet chemical method and fabricated as advanced bifunctional catalytic material. The as-prepared YM NSs catalyst were systematically scrutinized in terms of their crystal structure, morphologies, and optical properties using XRD, Raman, FE-SEM, HR-TEM, XPS and UV-DRS analysis. The bifunctional electro- and photocatalytic activity of as-prepared YM NSs was investigated towards the detection and degradation of β-adrenergic receptor-blocker agent acebutolol (ACB) for the first time. Interestingly, the YM NSs modified glassy carbon electrode (YM NSs/GCE) demonstrates an excellent electrocatalytic activity towards ACB with wider linear response ranges (0.01–9.6 µM, 13–1632 µM), lower detection limit (2.5 nM), good sensitivity (2.21 µA µM−1cm−2) and excellent selectivity even in the existence of some common cations, anions and biological substances. The sensor (YM NSs/GCE) was successfully applied to determine the level of ACB in tablet, urine and water samples. Furthermore, the YM NSs was performed as superior photocatalyst for the degradation of as detected ACB. The YM NSs could degrade above 99% and mineralize above 74% of ACB aqueous suspension under visible light irradiation with superior recycling stability.

High Pressure Behavior of Chromium and Yttrium Molybdate (Cr2Mo3O12, Y2Mo3O12).

The high pressure behavior of negative thermal expansion materials continues to be of interest, as their potential use in controlled thermal expansion composites can be affected by irreversible pressure-induced phase transitions. To date, it is not possible to predict the high pressure behavior of these compounds, necessitating measurements on each composition. In this work, high pressure synchrotron powder X-ray diffraction studies of Cr2Mo3O12 and Y2Mo3O12 were conducted in a diamond anvil cell. Chromium molybdate, which adopts the monoclinic P21/a structure under ambient conditions, was found to not undergo any crystalline-crystalline transitions up to 8.9 GPa. The orthorhombic ambient pressure polymorph of yttrium molybdate was found to undergo a phase transition to the monoclinic P21/a scandium tungstate structure below 0.13 GPa. This structure is frequently observed for related materials at low temperatures, but has never been reported for Y2Mo3O12. No additional changes in this material were observed up to 4.9 GPa. The fact that the monoclinic polymorphs of these materials do not undergo phase transitions within the studied pressure range makes them unique among A2M3O12 materials, as most isostructural compositions undergo at least one phase transition to crystalline high pressure phases.

Yttrium molybdates coating deposition of oxide-fibre/molybdenum-matrix composites

Shown a possibility to do a coating process on void-free surfaces which based on Yttrium molybdate on composite including molybdenum matrix by using ion-plasma deposition. Reported results of X-ray phase analysis of coating before and after annealing and also results of a microstructure analysis.

Preparation and properties of carbonyl iron particles (CIPs)/silicone resin composite with negative thermal expansion filler

Composites with tunable coefficient of thermal expansion (CTE) were prepared by incorporating orthorhombic Pbcn yttrium molybdate (Y2Mo3O12) particles at various weight percentages in carbonyl iron particles (CIPs)/silicone resin composite. The porous particles of Y2Mo3O12, which has isotropic negative thermal expansion confirmed by high-temperature X-ray powder diffraction, were synthesized using a citric acid method. Results show that porous Pbcn orthorhombic Y2Mo3O12 was obtained with αl = −1.04 × 10−5 /°C from 100 to 800 °C and the CTE of the CIPs/ silicone resin composite was reduced by around 45 % with the addition of Y2Mo3O12 at 20 wt.% loading. The complex permittivity and permeability were investigated in the frequency range of 2.6–18 GHz by wave guide method. Both the real (e′) and imaginary (e″) parts of the complex permittivity increase with increasing Y2Mo3O12 content, which is ascribed to interfacial interaction between the CIPs and Y2Mo3O12. For the permeability, the more dispersed Y2Mo3O12 fillers lead to the lower both the real (μ′) and imaginary (μ″) part of permeability due to the dilution effect induced by the addition of Y2Mo3O12.

Synthesis and characterization of neodymium doped yttrium molybdate high NIR reflective nano pigments

High near-infrared reflecting nano pigments Y6−xNdxMoO12 (x ranges from 0 to 1.0) based on yttrium molybdate doped with Nd3+ were synthesized by sol–gel. The pigments samples were characterized by means of TG-DTA, FTIR, XRD, SEM, UV–vis–NIR spectrophotometer and CIE L∗a∗b∗ color measurement. The results showed that the pigments crystallized completely at 900 °C with particle size less than 100 nm. The substitution of Nd3+ for Y3+ in Y6MoO12 induced the absorption in the region of 585–605 nm and as a result the color changed from yellow to yellow-green. The near-infrared reflectance and solar reflectance increased first and then decreased with increasing Nd3+ content. When x = 0.8, the pigment exhibited an optimum NIR solar reflectance of 89.9%. The thermal and chemical stability of the pigments was also evaluated.

Hydrothermal preparation and photoluminescent property of LiY(MoO4)2:Pr3+ red phosphors for white light-emitting diodes

Praseodymium doped lithium yttrium molybdate LiY1–xPrx(MoO4)2 (x=0.005–0.025) phosphors were successfully prepared by the hydrothermal method. The phase, morphology, and luminescent property of the prepared phosphors were investigated by X-ray diffraction and scanning electron microscopy. The results indicated that doping of Pr3+ ions did not change the main phase of the phosphors. The samples emitted red luminescence upon excitation at 453 nm and the strongest emission peak corresponding to the characteristic transition of the Pr3+ ion: 3P0→3F2 was observed at 657 nm. LiY(MoO4)2:Pr3+ red phosphors could be effectively excited by blue light emitting-diodes to emit red light; thus, acting as potential candidates for compensating the red light deficiency of cerium doped yttrium aluminum garnet yellow phosphor.

Pressure-induced crystal–amorphous transformation in Y2Mo3O12

In this work we investigate the vibrational properties of anhydrous and hydrated yttrium molybdate as a function of hydrostatic pressure. An analysis of vibrational modes suggests that the anhydrous material experiences a phase transformation from orthorhombic to a lower symmetry phase (probably monoclinic) about 0.3GPa, and to a highly disordered phase above 2.4GPa. The structural transformation to the high-pressure disordered phase is not reversible and suggests the onset of a pressure-induced amorphization process. The vibrational mode dependence on pressure is discussed considering lattice dynamics calculations.

Synthesis, Characterization and Optical Properties of Y<sub>6-x</sub>Sm<sub>x</sub>MoO<sub>12+σ</sub> Composite/Compounds Pigments with High Near-Infrared Reflectance

Novel high near-infrared reflecting inorganic pigments Y6-xSmxMoO12+σ (03+ in yttrium molybdate through a simple solid-state reaction method. The composites were characterized using scanning electron microscope, X-ray diffraction, UV-vis-NIR spectrophotometer and CIE 1976 L*a*b* color scales. The substitution of Sm3+ for Y3+ in Y6MoO12 changed the color from bright yellow to dark yellow and most importantly increased near-infrared reflectance in the wavelength range of 700-2500 nm. The chemical stability of the pigments was also evaluated.

Complex potassium yttrium molybdate phosphates K2Y1 − x Eu x (MoO4)(PO4)0.9(VO4)0.1: Synthesis and study of luminescent properties

Samples with various dopant contents were obtained using solid-state and sol-gel methods. The resulting single-phase samples have the formula K2Y1 − xEux(MoO4)(PO4)0.9(VO4)0.1 (x = 0, 0.005, 0.01, 0.02, 0.03) and are isostructural with K2Y(MoO4)(PO4). The possibility of formation of complex molybdate vanadates M2IMIII(MoO4)(VO4). was studied. Unlike their precursor K2Y(MoO4)(PO4), the complex potassium yttrium molybdate phosphates obtained are deliquescent. Their structures contain no water molecules. The absorption and emission spectra of the compounds under study were recorded. In all the spectra, the electric dipole transition 5D0−7F2 (616 nm) is appreciably more intense than the magnetic dipole transition 5D0−7F1 (590 nm). This suggests that the coordination environment of the Eu3+ ion keeps asymmetric. The excitedstate lifetimes of anhydrous and humidified samples were determined. The average lifetime is the same for all samples (≈1.5 ms), which is due to the stability of their structures.

The synthesis, characterization and optical properties of silicon and praseodymium doped Y 6MoO 12 compounds: Environmentally benign inorganic pigments with high NIR reflectance

Novel, yellow, brown and brick-red colored, near-infrared reflective pigments based on yttrium molybdate doped with metal ions such as Si 4+ or Pr 4+ are described. Replacing Si 4+ for Y 3+ in Y 6MoO 12 changed the color from light-yellow to dark-yellow and the band gap decreased from 2.60 to 2.45 eV due to O 2p-Mo 4d charge transfer transitions. In contrast, replacing Pr 4+ for Y 3+ changed the color from light-yellow to dark brown and the band gap shifted from 2.60 to 1.90 eV. The coloring mechanism is based on the introduction of an additional 4f 1 electron energy level of Pr 4+ between the valence and conduction bands. The NIR reflectance of the pigments on asbestos cement sheet was measured.

Dependence of upconversion emission intensity on Yb3+ concentration in Er3+/Yb3+ co-doped flake shaped Y2(MoO4)3 phosphors

Yttrium molybdate phosphors with fixed Er3+ and various Yb3+ concentrations were synthesized via a co-precipitation method. The crystal structure and the morphology of the phosphor were characterized by means of x-ray diffraction and field-emission scanning electron microscopy. Under 980 nm excitation, red and green upconversion emissions centred at 660, 553 and 530 nm were observed. Quantitative analyses on the dependence of upconversion emission intensity on the working current of a laser diode (LD) indicated that two-photon processes are responsible for both red and green upconversion emissions in both cases of low and high Yb3+ concentrations. The relationship between the emission intensity ratio of 2H11/2 →4I15/2 to 4S3/2 →4I15/2 and the working current of the LD was studied for the samples doped with low and high Yb3+ concentrations. Finally, a set of rate equations was established based on the possible upconversion mechanism, and an empirical formula was proposed to describe the Yb3+ concentration dependence of upconversion emission intensity; the empirical formula fits well with the experimental data.

Rapid synthesis of A 2(MoO 4) 3 (A = Y 3+ and La 3+)with a CO 2 laser

Negative thermal expansion material of yttrium molybdate and positive thermal expansion material of lanthanum molybdate have been successfully synthesized by rapid solidification with a CO 2 laser. Both materials were solidified in densely packed blocks with smooth surface and glazing color. They have similar microstructures consisting of nano-particles or nano-dendrites with grain sizes around 20–30 nm. Raman spectroscopic and XRD analyses reveal that lanthanum molybdate crystallized in a high temperature phase of tetrahedral La 2Mo 3O 12, whereas yttrium molybdate crystallized in an orthorhombic Y 2Mo 3O 12. This synthetic route is a very rapid process with which a sample can be synthesized within a few seconds and holds prospect for the synthesis of other rare earth molybdates and tungstates.

Effect of Water Species on the Phonon Modes in Orthorhombic Y2(MoO4)3 Revealed by Raman Spectroscopy

Negative thermal expansion material of yttrium molybdate has been synthesized by rapid solidification with a CO2 laser. It crystallized in the orthorhombic phase with unique microstructures consisting of nanoparticles or nanodendrites with grain sizes around 20−30 nm. Raman spectroscopic and XRD analyses reveal that the presence of water species hinders not only the rocking motion but every type of motion of the corner shared polyhedra. Because of the presence of water species, degeneracy of the Raman bands happens for symmetric stretching, asymmetric stretching, and the bending modes, and the lattice, translational, and librational modes cannot be observed. The release of water species below 403 K (388 K for the newly prepared sample or 383 K in the second temperature cycle) has little whereas that above this temperature has great effect on the stretching and bending vibrations and also the librational and translational modes. This indicates that the water species which are released within the first step do not interact with the MoO4 tetrahedra in the Y2Mo3O12 framework while those released in the second step have a direct interaction. It is suggested that the translational and librational motions are closely coupled with stretching and bending vibrations. They together give rise to the negative thermal expansion.