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.
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
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.
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.
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.
