10361-92-9Relevant articles and documents
Kinetics of yttrium oxide carbochlorination
Gaviría,Fouga,Bohé
, p. 24 - 33 (2011)
The chlorination kinetics of the Y2O3-sucrose carbon system was studied by thermogravimetry. This work is a continuation of a previous one in which the reaction stages and the stoichiometry of each reaction have been determined. The influence of carbon content, total flow rate, sample initial mass and chlorine partial pressure was evaluated. The effect of carbon content on the reactive mixture was studied between 6.7 and 70% (carbon mass/total mass). The results showed that the reaction rate of each stage is strongly increased as the carbon content increases and the range of occurrence of the stages depends on the amount of carbon in the solid reactive mixture. The formation reaction of YOCl (STAGE I) is chemically controlled for temperatures lower than 700 °C with average effective activation energies of 165 ± 6 and 152 ± 7 kJ/mol for 8.7 and 16.7%C, respectively. The formation of the YOCl follows a nucleation and growth mechanism, with a combination of continuous nucleation and site saturation, and anisotropic growth controlled by diffusion. The kinetics of STAGE I can be expressed by the following global rate equation that includes the variables analyzed:dαdt=k0Bexp- EaRgTpCl2n(1-α)-ln(1-α)(n-1)/n where k0B = 1.9 × 104, n = 1.20 for 8.7%C, and k0B = 8.4 × 103, n = 1.14 for 16.7%C. STAGES II and III correspond to the YOCl carbochlorination to form YCl3, being these stages kinetically different. It was not possible to obtain kinetic parameters for these stages. The reaction rate of STAGE II is affected by diffusion of Cl2 through the gas film surrounding the sample and mass changes in STAGE III have two opposite components: formation and evaporation of liquid YCl3.
Coordination between yttrium ions and amide groups of polyamide 6 and the crystalline behavior of polyamide 6/yttrium composites
Liu, Shaoxuan,Zhang, Chengfeng,Liu, Yuhai,Zhao, Ying,Xu, Yizhuang,Ozaki, Yukihiro,Wu, Jinguang
, p. 63 - 69 (2012)
Different amounts of yttrium ions were introduced into polyamide 6 (PA6) matrix by solution casting process. Structure, morphology and properties of the obtained PA6/Y3+ composite films were investigated by using FT-IR spectroscopy, Raman spectroscopy, scanning electron microscope (SEM), polarized optical microscope (POM) and differential scanning calorimeter (DSC) methods. Yttrium ions show strong coordination ability and their complexation with amide groups of PA6 can be reflected by the appearance of new bands in the amide A and amide I regions in FT-IR and Raman spectra. Furthermore, the FT-IR and Raman spectra of the PA6/Y3+ composite show that the resultant chain conformations of the amide groups in the composite films are twisted from the ideal trans conformation. The DSC results reveal that Y3+ ions cause a significant reduction of the melting point of PA6. In addition, the existence of Y3+ prevents the crystallization of molten PA6/Y3+ composite films during the cooling process. Moreover, the PA6/Y3+ composite can convert into γ phase PA6 or α phase PA6 when different solvents are used to remove Y3+ ions and induce crystallization of PA6.
Preparation of the Bis(trimethylsilyl)amido Lanthanide Chlorides 2(μ-Cl)(thf))2>(thf=tetrahydrofuran), and the Crystal and Molecular Structures of the Gadolinium and Ytterbium Complexes
Aspinall, Helen C.,Bradley, Donald C.,Hursthouse, Michael B.,Sales, Keith D.,Walker, Nigel P. C.,Hussain, Bilquis
, p. 623 - 626 (1989)
Reaction of LnCl3 with 2 equivalents of LiL in tetrahydrofuran (thf) at -5 deg C yields for Ln=Eu, Gd, or Yb or for Ln=Y.X-Ray crystal structure analysis of the compounds of Gd and Yb confirms the formation of halide-bridged dimers.In the M2Cl2 bridging unit the M-Cl bond lengths differ slightly and the angle at the metal (ca. 74 deg) is much smaller than at chlorine (ca. 106 deg).The metal co-ordination geometries are irregular but can be best described as distorted trigonal bipyramidal with the bridging chlorines spanning one axial and one equatorial site.The bond lengths M-Cl and M-N indicate a Gd-Yb radius difference of ca. 0.07 Angstroem, but the M-O distances differ by 0.093 Angstroem.Variable-temperature n.m.r. studies of and show that there is free rotation about Ln-N and Ln-O bonds at room temperature.These rotations are frozen out at low temperatures to give a solution structure having higher symmetry (C2n) than that found in the crystal.
Reduction kinetics of NiO-YSZ composite for application in solid oxide fuel cell
Yoshito,Matos,Ussui,Lazar,Paschoal
, p. 303 - 308 (2009)
A porous nickel-8 mol% yttria stabilized zirconia (Ni-8YSZ) composite, used as anode for solid oxide fuel cell, was obtained by reduction of NiO-8YSZ cermet. The first goal was the evaluation of the temperature effect of powder processing by thermogravime
Thermodynamics of lanthanide elements, IV. Molar enthalpies of formation of Y3+(aq), YCl3(cr), YBr3(cr), and YI3(cr)
Xiang-Yun, Wang,Zhu, Jin Tian,Goudiakas, J.,Fuger, J.
, p. 1195 - 1202 (1988)
Enthalpies of solution of high-purity yttrium metal and of yttrium trichloride, tribromide, and triiodide in hydrochloric acid of various molalities lead to the following standard molar enthalpies of formation ΔfH0m/(kJ *
Low-temperature heat capacity and thermochemical study of crystalline [Y2(Ala)4(H2O)8] (ClO4)6 (Ala=CH3CH(NH3+)COO-)
Liu, Beiping,Zhao, Xinsheng,Li, Lin,Sun, Lixian,Tan, Zhi-Cheng
, p. 59 - 64 (2002)
The solid complex of rare-earth compound with alanine, [Y2(Ala)4(H2O)8] (ClO4)6 were synthesized, and the heat capacities of the solid complex were measured with a small sample high-precision automated adiabatic calorimeter over the temperature range from 78 to 400 K. The melting point, molar enthalpy and entropy of fusion of the complex were determined to be 378.73 ± 0.01 K, 16.78 ± 0.02 kJ mol-1, 44.30 ± 0.04 JK-1 mol-1, respectively. Thermal decomposition of the complex was studied through differential scanning calorimetry (DSC) and thermogravimetry (TG). The possible mechanisms of the thermal decomposition reaction was suggested according to the TG and DSC results.
Effect of SiO2 on densification and microstructure development in Nd:YAG transparent ceramics
Stevenson, Adam J.,Li, Xin,Martinez, Miguel A.,Anderson, Julie M.,Suchy, Daniel L.,Kupp, Elizabeth R.,Dickey, Elizabeth C.,Mueller, Karl T.,Messing, Gary L.
, p. 1380 - 1387 (2011)
This paper examines the influence of SiO2 doping on densification and microstructure evolution in Nd3xY 3-3xAl5O12 (Nd:YAG) ceramics. Nd:YAG powders were doped with 0.035-0.28 wt% SiO2 and vacuum sintered between 1484° and 1750°C. 29Si magic-angle spinning nuclear magnetic resonance showed that Si4+ substitutes onto tetrahedrally coordinated Al3+ sites. High-resolution transmission electron microscopy showed no grain boundary second phases for all silica levels in samples sintered at 1600°-1750°C. Coarsening was limited by a solute drag mechanism as suggested by cubic grain growth kinetics and transmission electron microscopy energy-dispersive X-ray spectroscopy observations of increased Nd3+ concentration near grain boundaries. Increasing SiO2 content increased both densification and grain growth rate and led to increasingly coarsening-dominated sintering trajectories. Fine-grained (82% real in-line transmission) ceramics were produced by sintering 0.035 wt% SiO2-doped ceramics at 1750°C for 8 h. Coarse-grained (18 μm), transparent samples were obtained with 0.28 wt% SiO2-doped Nd:YAG when sintered at 1600°C for 8 h.
Carbochlorination of yttrium oxide
Gaviría,Bohé
, p. 100 - 110 (2010)
The reaction of chlorination of a mixture composed by Y2O 3 and sucrose carbon was studied by thermogravimetry over a temperature range of 550-950 °C. The reaction proceeds through several successive stages. The first of them is the formation of solid yttrium oxychloride (YOCl) and subsequently the YOCl is carbochlorinated to produce YCl3 (solid or liquid, depending on the temperature) in two stages. The stoichiometries of the first stage and the global reaction were estimated by mass balances, taking into account the chlorine adsorbed by the remainder carbon. The results showed that the reactions involved progress with the formation of CO2 and CO in the temperature range of 600-775 °C. The interaction between sucrose carbon and chlorine was analyzed by thermogravimetry in order to quantify the amount of chlorine which is adsorbed on its surface. It was studied the effect of the temperature and initial mass of carbon. The morphological analysis performed by SEM of partially reacted samples showed that the formation of YOCl proceeds through a mechanism of nucleation and growth. For temperatures above 715 °C the final product of the carbochlorination is liquid YCl3, whose evaporation is observed in the thermogravimetry. The evaporation kinetics was analyzed in argon atmosphere and from the thermogravimetric curves was determined a value of 250 kJ/mol for the heat of evaporation of YCl3. This value is consistent with a partial dimerization of the gaseous chloride.
Water-soluble Yb3+, Tm3+ codoped NaYF4 nanoparticles: Synthesis, characteristics and bioimaging
Chen, Huan,Zhai, Xuesong,Li, Duo,Wang, Lili,Zhao, Dan,Qin, Weiping
, p. 70 - 73 (2011/12/13)
Water soluble NaYF4 nanocrystals codoped with 20 mol% Yb 3+, 0.5 mol% Tm3+ were prepared by a facile solvothermal approach using polyvinylpyrrolidone (PVP) as a surfactant. The upconversion NaYF4 nanocrystals were pure cubic phase with an average size of ～40 nm. They could be well redispersed in water to form a clearly transparent solution without obvious precipitation. With the excitation of a 980-nm diode laser, the nanocrystal solution presents bright violet and blue upconversion luminescence. These upconversion nanoparticles (UCNPs) were incubated with HeLa cells at 37 °C for 24 h, and bright blue upconversion luminescence were observed from the UCNPs endocytosed into the HeLa cells on a microscope equipped with a 980-nm fiber laser. These results indicated that the UCNPs had potential applications for biological imaging as luminescent probes.
Self-assembled light lanthanide oxalate architecture with controlled morphology, characterization, growing mechanism and optical property
He, Hongmei,Zhang, Youjin,Zhu, Wei,Zheng, Ao
, p. 1546 - 1552 (2011/10/01)
Flower-like Sm2(C2O4)3· 10H2O had been synthesized by a facile complex agent assisted precipitation method. The flower-like Sm2(C2O 4)3·10H2O was characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, thermogravimetry- differential thermal analysis and photoluminescence. The possible growth mechanism of the flower-like Sm2(C2O4) 3·10H2O was proposed. To extend this method, other Ln2(C2O4)3·nH2O (Ln = Gd, Dy, Lu, Y) with different morphologies also had been prepared by adjusting different rare earth precursors. Further studies revealed that besides the reaction conditions and the additive amount of complex agents, the morphologies of the as-synthesised lanthanide oxalates were also determined by the rare earth ions. The Sm2(C2O4) 3·10H2O and Sm2O3 samples exhibited different photoluminescence spectra, which was relevant to Sm 3+ energy level structure of 4f electrons. The method may be applied in the synthesis of other lanthanide compounds, and the work could explore the potential optical materials.
