Yttrium Acetate Research Articles

Photosensitive YBCO gel film and its patterning by sol–gel process

The YBCO precursor solution was prepared using yttrium acetate, barium acetate and copper acetate as starting material, diethylenetriamine, trifluoroacetate, acrylic acid (AA) as chemical additives, methanol as solvent. The precursor solution was modified by AA, in which the Cu 2+ of Cu(OAc) 2 and AA were reacted to form the photosensitive copper complex. The coated gel film using this precursor solution exhibited the photosensitivity to UV light at around 245 nm. Utilizing the photosensitivity, the patterned YBCO film with a high critical transition temperature ( Tc) of 91.5 K was fabricated.

Sintering and conductivity of BaCe 0.9Y 0.1O 2.95 synthesized by the sol–gel method

Ceramic powders of BaCe 0.9Y 0.1O 2.95 (BCY10) have been prepared by the sol–gel method. Barium and yttrium acetate and cerium nitrate were used as ceramic precursors in a water solution. The reaction process studied by DTA–TG and XRD showed that calcination of the precursor powder at T ≥ 1000 °C produces a single perovskite phase. The densification behaviour of green compacts studied by constant heating rate dilatometry revealed that the shrinkage rate was maximal at 1430 °C. Sintered densities higher than 95% of the theoretical one were thus obtained below 1500 °C. The bulk and additional blocking effects were characterized by impedance spectroscopy in wet atmosphere between 150 and 600 °C. A proton conduction behaviour was clearly identified. The blocking effect can be related to a space-charge depletion layer of protons in the vicinity of grain boundaries.

Analysis of the supercritical antisolvent mechanisms governing particles precipitation and morphology by in situ laser scattering techniques

A general description of the mechanisms governing the supercritical (sc) antisolvent (SAS) process is given. It simplifies the complex interactions of phase equilibria, jet fluid dynamics and mass transfer by two characteristic and competing times. One of them characterizes the time for the disappearance of the interface between the liquid and the fluid phase (liquid/fluid interface) where the fluid phase is represented either by a liquid or by a sc fluid phase depending on the pressure and the mixture composition. The second one is the time for particle precipitation. This description is experimentally supported by the investigation of the SAS process at various process conditions using in situ light scattering measurements which allow the access to both, to the liquid/fluid (droplets) and to the solid/fluid (particles) interface. SAS experiments were conducted by injecting the solution – yttrium acetate dissolved in dimetylsulfoxide – into the antisolvent carbon dioxide with different flow rates at a constant carbon dioxide molar fraction. The variation of the liquid flow rate did not affect the morphology of the precipitate. As a consequence, the occurrence of nano particles, micro particles and expanded micro particles can be assigned to the precipitation of the particles from a single-phase mixture, a two-phase mixture of short lifetime and a two-phase mixture of long lifetime, respectively. These particular precipitation regimes have been experimentally attained by varying either the pressure or the solute concentration.

Enhanced Jc–B propertiesof MgB2 tapes by yttrium acetate doping

We report the effect of yttrium acetate addition on in situ powder-in-tube processedMgB2/Fe tapes. The amount of yttrium acetate was varied from 0 to 20 wt% and sintering was performed at700–850 °C for 1 h in a flowing Ar atmosphere. We found that a significantJc–B enhancement was easily achieved in high field by yttrium acetate doping. At 4.2 K, the transportJc for the best yttrium-acetate-added tapes (10 wt%) reached almost104 A cm − 2 at 12 T. Theimprovement of Jc performance in the yttrium-acetate-doped samples can be attributed to the combination ofthe carbon substitution for B and stronger flux pinning.

Self-propagating high-temperature synthesis of Y2O3 powders from Y(NO3)3x (CH3COO)3(1 − x) · nH2O

We have studied the self-propagating high-temperature synthesis (SHS) of yttrium oxide from Y(NO3)3x(CH3COO)3(1 − x) · nH2O (0.3 ≤ x ≤ 0.7) acetate nitrates, calculated their standard enthalpies of formation using the method of valence states of atoms in a chemical compound, and compared calculated and experimentally determined yttrium oxide SHS temperatures. Using thermogravimetry and differential scanning calorimetry data and thermodynamic analysis, we have determined the optimal range of yttrium acetate nitrate compositions for the SHS of Y2O3 powder.

Thermoanalytical study of the formation mechanism of yttria from yttrium acetate

The processes involved in the thermal decomposition of yttrium acetate tetrahydrate, Y(CH 3COO) 3·4H 2O, in air and in an inert atmosphere have been analyzed by thermoanalytical techniques (thermogravimetry, differential thermal analysis and evolved gas analysis) and by the structural characterization (X-ray diffraction, infrared spectroscopy, elemental analysis and scanning electron microscopy) of intermediates and final products. Decomposition of yttrium acetate is an endothermic transformation that takes place in a temperature range between 350 and 900 °C. The evolution of the mass during the decomposition process is not affected by the presence of oxygen. The process is initiated by the rupture of the bond between the metallic cation and the acetate ligand. This initial step (350–450 °C) involves the formation of amorphous yttrium hydroxide and yttrium carbonate and is characterized by a fast mass loss rate. A sudden decrease of the mass loss rate indicates a change in the decomposition kinetics that continues with the decomposition of yttrium hydroxide and yttrium carbonate. The main effect of an oxygen atmosphere is an intense exothermic process due to the combustion of organic species in the gas phase.

Influences of Y 2O 3 nanoparticle additions on the microstructure and superconductivity of YBCO films derived from low-fluorine solution

Low-fluorine YBCO precursor solutions with metallic ion molar ratio of Y 3+:Ba 2+:Cu 2+ = (1 + λ):2:3 ( λ = 0, 0.05, 0.1, 0.15, 0.2, 0.3) were prepared using fluorine-free yttrium acetate, copper acetate and fluorinated Ba-TFA as starting materials. Using the yttrium-excess YBCO solutions, YBCO–Y 2O 3 nanocomposite films were prepared on (0 0 1)-oriented LaAlO 3 single-crystal substrates by dip-coating process. The growth orientation and microstructure of the as-prepared YBCO–Y 2O 3 nanocomposite films were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Both the electrical transport and magnetization methods were used to measure the superconducting performance of the films. The results show that Y 2O 3 nanoparticles with the diameter of 5–6 nm are formed and well dispersed in YBCO matrix. These nanoscaled Y 2O 3 nanoparticles and the induced nano-sized crystal defects can act as the flux pinning centers, thus leading to the improvement of critical current density J c of YBCO films at all magnetic field orientations.

Imaging the supersaturation in high-pressure systems for particle generation

The supersaturation which is the driving force for particle precipitation was quantified in situ for the injection of a solution into a supercritical antisolvent. Firstly, saturation mole fractions of the solute yttrium acetate were measured via elastic light scattering in the homogeneous ternary system, which is composed of the solute itself, the solvent dimethylsulfoxide and the antisolvent carbon dioxide. The saturation experiments were carried out at pressures of 8.5, 12 and 16 MPa and at a temperature of 313 K. Secondly, applying a Raman based optical measurement technique the actual solute mole fraction was imaged in situ during the injection of the solution (solute dissolved in solvent) into the antisolvent. The injection experiments were carried out at pressures of 12 and 16 MPa and at a temperature of 313 K. Finally, the ratio of the actual solute mole fractions and the saturation solute mole fractions, which were measured during the injection experiment and during the saturation experiment, respectively, quantifies the supersaturation. High supersaturation values are evidenced already close to the nozzle exit. For the first time, an optical method was developed to measure the supersaturation in situ in a dynamic process under high-pressure.

Water-Vapor-Controlled Reaction for Fabrication of YBCO Films by Fluorine-Free Sol-Gel Process

Fluorine-free sol-gel process is a potential technique in preparing YBa2Cu3O7-δ (YBCO) films due to avoiding the release of HF gas. In this paper, yttrium acetate, barium acetate, and copper acetate are used as the starting materials to synthesize a novel YBCO fluorine-free precursor solution. The phase evolution during the heat-treatment process of YBCO films and YBCO phase formation were studied, and the results show that the introduction of water vapor at the stage of high-temperature heat treatment can make the BaCO3 phase become converted into the Ba(OH)2 phase, which can be used as the barium source to react with CuO and Y2O3 to generate the YBCO phase, thus achieving the purpose for fabrication of high-performance YBCO films by fluorine-free sol-gel process. Through this approach, YBCO films with c-axis orientation and an excellent superconducting property can be obtained on a (001)-oriented LaAlO3 (LAO) substrate. Superconducting property tests indicate that the superconducting critical transition temperature Tc is approximately 90 K, and the transition width T deduced from the R-T curve is less than 1 K; the critical current density Jc is 1.65 MA/cm2 (77 K, 0 T), as tested by an electric transport method, and 1.83 MA/cm2 (77 K, 0 T), as measured by magnetization measurement.

ChemInform Abstract: Synthesis of Yttrium Aluminum Garnet by the Glycothermal Method.

The reaction of a stoichiometric mixture of aluminum isopropoxide and yttrium acetate in 1,4-butanediol at 300°C yielded crystalline yttrium aluminum garnet having an approximate particle size of 30 nm. No other phases were detected. The use of ethylene glycol in place of 1,4-butanediol afforded an amorphous product.

Fabrication and Characterization of Boron Supported YBCO Superconductive Nanofibers by Electrospinning

This study is related to the preparation of boron supported YBa2Cu3O7 (YBCO) superconducting material. The first step was the preparation of a composite formed by mixing yttrium, barium, and copper acetates with polyvinyl alcohol (PVA) at a suitable temperature. The resulting composite polymer was electrospun to produce nanofibers. Finally, the obtained nanofibers were subjected to thermal treatments at 500°C, 600°C and 1000°C to elucidate their morphological properties. The conductivity of the nanofibers was measured by the four probe techniques, and the boron supported polymer was found that it had a higher conductivity. Differential Scanning Calorimetry (DSC) data for the boron doped material revealed that the addition of boron increased the thermal resistance of the fibers. Scanning electron microscopy (SEM) images of the fibers showed that they were homogeneously electrospun, and there was no beading or heaping on them. Keywords: Superconducting, Electrospinning, YBCO, nanofibers

A Convenient One-Pot Biginelli Reaction Catalyzed by Y(OAc)3: An Improved Protocol for the Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones and Their Sulfur Analogues

Yttrium(III) acetate hydrate-catalyzed novel synthesis of 3,4-dihydropyrimidin-2(1H)-(thio)one derivatives was achieved through one-pot three-component condensation of diversified aldehydes, β-ketoesters and urea or N-methylurea or thiourea with a molar ratio of 1:1:1.4. In comparison to the classical Biginelli approach, this catalytic method has the advantages of short reaction time and improved product yield.

Photostability of YAG : Ce3 + Nanophosphors Synthesized by Glycothermal Method

Yttrium–aluminum garnet nanophosphor powder is prepared from yttrium acetate, cerium acetate, and aluminum isopropoxide by a one-step glycothermal method, i.e., by autoclave treatment in 1,4-butanediol at for 2 h. The gradual decrease in the intensity of photoluminescence corresponding to the transition of is observed under the continuous irradiation of blue excitation light. This photobleaching behavior is not observed for the micrometer-sized bulk. Two-step glycothermal synthesis, i.e., the repeated autoclave treatment, causes the growth of nanoparticles and the improvement of crystallinity, and hence suppresses the photobleaching. The suppression of photobleaching is more prominent for the sealed transparent film produced from the paste compared with the powder samples. The photobleaching is attributed to the photo-oxidation of to near the surface of nanoparticles with a high proportion of surface atoms, as confirmed by electron energy loss spectroscopy.

Two synthesis routes of organometallic precursors for the elaboration of SiCNYO pre‐alloyed nanopowders

AbstractTwo routes were simultaneously investigated to prepare organometallic precursors. They were characterized by NMR and FTIR techniques. In the first route, yttrium acetate was silylated by trimethylchlorosilane before its dissolution in hexamethydisilazane. That leads to a liquid precursor containing SiCNYOH elements. In the second route, a precursor with the same elements was elaborated by dissolution of an amminolysed yttrium compound in tetramethyldisiloxane. The amminolysed yttrium compound was obtained through the amminolysis of the yttrium trichloride by triethylamine [N(C2H5)3]. Copyright © 2010 John Wiley & Sons, Ltd.

Study of Fluorescence of Yttrium Doped Zinc Sulfide Nanoparticles

Doped ZnS nanocrystals have attracted attention since 1994. Previous results suggest that doped semiconductor nanocrystals form a new class of luminescent materials, which have a wide range of applications in displays, lighting, sensors and lasers. In this work we synthesized Y3+ doped ZnS nanoparticles by a chemical precipitation method. The reaction was performed with ZnSO4, Na2S, phosphates and Yttrium acetate in aqueous solution. Fluorescence (FL) studies of these nanoparticles have been carried out. FL analysis reveals that the incorporation of Yttrium and phosphates to colloidal solution of ZnS nanoparticles enhances the FL signal by 6-7 times of magnitude compared with uncapped ZnS nanoparticles.

Effect of copper content in precursor solution on the superconducting properties of YBCO films derived from low-fluorine solution

Four low-fluorine solutions with different stoichiometry of Y:Ba:Cu = 1:2: ξ ( ξ = 3, 3.5, 4, 4.5) were prepared using Ba-TFA, yttrium and copper acetate as precursors. YBa 2Cu 3O 7− δ (YBCO) films derived from these low-fluorine solutions were coated on LaAlO 3 (LAO) single crystal substrates by dip-coating process. The effect of copper stoichiometry in precursor solution on the microstructure and superconductivity of YBCO films was studied. The growth orientation and microstructure of the films were characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). The results show that there are large volume fraction of a-axis oriented YBCO grains in the films derived from precursor solutions with stoichiometry of Y:Ba:Cu = 1:2: ξ ( ξ = 3, 3.5, 4.5), while the films from the solution with stoichiometry of Y:Ba:Cu = 1:2:4 mainly grow along c-axis orientation and the volume fraction of c-axis oriented grains is 96.33%. Superconductivity test indicate that the film derived from the precursor solution with stoichiometry of Y:Ba:Cu = 1:2:4 exhibits excellent superconducting properties with the critical transition temperature T c approximate 90 K, the sharp transition temperature Δ T below 1 K and the critical current density J c over 1 MA/cm 2 (77 K, 0 T).

Sol–Gel Combustion Synthesis of Nanocrystalline YAG Powder from Metal‐Organic Precursors

Yttrium aluminum garnet (Y3Al5O12, YAG) nanocrystalline powders were synthesized by a novel sol–gel combustion process. Yttrium acetate and aluminum sec‐butoxide were used as the precursors and triethanolamine was used as the chelating agent and fuel. Thermal and crystallization behaviors of the YAG precursor powders were investigated by thermal gravimetric differential thermal analysis (DTA), Fourier transform infrared spectrum, and X‐ray diffraction. The combustion‐synthesized powders are amorphous and transform to a pure YAG crystalline phase at 900°C. The crystallization activation energy of amorphous YAG precursor was investigated by variable heating rate DTA. The calculated activation energy is 58.9 KJ/mol. The average crystalline size of heat‐treated YAG powders at 900°C is ∼20 nm.

Morphology and structure of rare earth borate (REBO3) synthesized by glycothermal reaction

The glycothermal reaction of the rare earth (RE) acetates with trimethoxyborane (RE/B = 1) at 315 °C for 2 h yielded REBO3 for Tm, Yb and Y. For Gd–Er, REBO3 was contaminated with amorphous products. Mixtures of RE(OAc)O, REBO3 and amorphous products were obtained for Sm and Eu, while only RE(OAc)2(OH) was obtained for La. The space group of the REBO3 crystal obtained from Sm–Er and Y was P63/m, and mixture of REBO3 crystals with P63/m and R\( \ifmmode\expandafter\bar\else\expandafter\=\fi{3} \)c were obtained for Tm and Yb. Prolonged reaction time (6 h) yielded REBO3 without contamination of the amorphous product or RE(OAc)O for Eu–Yb and Y. For the reaction of yttrium acetate and trimethoxyborane with Y/B ratio of 1/3–3/1 for 2 h, YBO3 was only the binary oxide detected. The YBO3 particles were spheroidal with a diameter of 1 μm. The selected area electron diffraction of a whole particle indicated that the each particle is a “single crystal” of YBO3 grown from one nucleus.

Synthesis of nanocrystalline rare earth oxides by glycothermal method

The reaction of yttrium acetate hydrate in 1,2-propanediol at 300 °C yielded a product containing acetate groups and glycol moieties. From this product, Y 2O 3 was directly crystallized at 400 °C without the formation of a carbonate oxide phase. The thus-obtained Y 2O 3 samples had a small crystallite size (2.2 nm) and significantly large surface area (280 m 2/g). Other nanocrystalline rare earth (Gd–Yb) oxides were also obtained by this method.

Glycothermal Synthesis and Magnetic Properties of YIG/YAG Nanoparticles

Yttrium aluminum garnet (YAG) nanoparticles of 14.5±3.2 nm in diameter are synthesized from yttrium acetate and aluminum isopropoxide in 1,4-butanediol by autoclave treatment at 300oC for 2h. Yttrium iron garnet (YIG) / YAG composite nanoparticles of 21.1±4.9 nm in diameter are synthesized from yttrium acetate and iron(III) acetylacetonate in 1,4-butanediol by autoclave treatment at 300oC for 2h using YAG nanoparticles as the seed. In contrast, YIG is not formed by the same procedure in the absence of the YAG seed. The saturation magnetizations of nanoparticles with different YIG/YAG ratios range from 11.9 to 17.8 emu/g. YIG/YAG nanoparticles dispersed in the agarose gel are observed by magnetic resonance imaging (MRI). The degree of the negative MRI contrast depends on the concentration of YIG/YAG nanoparticles.