Phase relations in the system ZnV2O6 -ZnFe2O4

Using DTA and XRD methods, a diagram of phase equilibria in ZnV₂O₆-ZnFe₂O₄ system has been constructed. System ZnV₂O₆-ZnFe₂O₄ is in subsolidus area a real binary system and its components form a compound Zn₂FeV₃O₁₁. Zn₂FeV₃O₁₁ melts incongruently at 835±5°C with deposition of two solid phases: b-Zn₂V₂O₇ and ZnFe₂O₄. This revised version was published online in July 2006 with corrections to the Cover Date.     

Phase equilibria in the system NiO-V2O5-Fe2O3 in subsolidus area

Reactivity of FeVO₄ towards Ni₂V₂O₇ and Ni₃V₂O₈ in the solid state was investigated. On the base of XRD and DTA results, phase diagrams in subsolidus area of the FeVO₄-Ni₂V₂O₇ and FeVO₄-Ni₃V₂O₈ intersections of the ternary system NiO-V₂O₅-Fe₂O₃ have been worked out and the phase diagram of this ternary system in subsolidus area in the whole component concentration range has been verified. This revised version was published online in July 2006 with corrections to the Cover Date.     

Phase relations in subsolidus area of ZnO-V2O5-Fe2O3 system

Phase equilibria in subsolidus area in the ZnO-V₂O₅-Fe₂O₃ system have been investigated over the whole concentration range of the oxides. The components of this system form two compounds: Zn₂FeV₃O₁₁ and Zn₃Fe₄(VO₄)₆. A solidus area projection onto the component concentration triangle plane of the ZnO-V₂O₅-Fe₂O₃ system has been constructed using DTA and XRD methods. 11 subsidiary subsystems can be distinguished in this system. Melting temperatures of mixtures of solid phases coexisting at equilibrium in each of subsidiary subsystems were determined. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis,characterization, and catalytic application of Fe3O4‐Si‐[CH2]3‐N=CH‐aryl for the efficient synthesis of novel poly‐substituted pyridines

Fe₃O₄ magnetic nanoparticles (MNPs) were functionalized by aminopropylsilane and reacted with aromatic aldehyde, and Fe₃O₄‐Si‐[CH₂]₃‐N=CH‐Aryl and Fe₃O₄‐Si‐(CH₂)₃‐NH‐CH₂‐Aryl MNPs were prepared as novel magnetic nanocatalysts. Fourier transform infrared (FT‐IR), X‐ray diffraction (XRD), and scanning and transmission electron microscopy (SEM and TEM) were used to identify the MNPs. The catalytic activity of the MNPs was evaluated in the one‐pot synthesis of some novel poly‐substituted pyridine derivatives.     

Lyotropic mesophases of cellulose in the ammonia/ammonium thiocyanate solvent system: Phase relationships

Mesophase formation of the cellulose/NH₃/NH₄SCN system has been studied as a function of system composition at 25°C. Compositions for incipience of mesophase formation and for wholly anisotropic phase formation have been determined and relevant phase diagrams constructed. The biphasic gap narrowed when the solvent composition approached 75.5 weight percent NH₄SCN and as the cellulose concentration decreased. As solvent composition was changed, the minimum cellulose volume fraction for mesophase formation ranged between 0.02 to 0.045.     

Study on the Phase Diagram of CsCl-CeCl3-HCl(11%)-H2O System and the Properties of the Compounds

The equilibrium solubility of CsCl-CeCl3-HCl(11%)-H2O qua-ternary system at 25℃ has been determined by the physicchemical analysis method ,and the phase diagram was plotted, Two new double salts 3CsCl.CeCl3.3H2O and CsCl.CeCl3.4H2O obtained from the complicated system were identified and characterized by XRD,TG-DTA ,DSC,UV and fluorescence spectroscopy, Studies on the fluorescence excitation and emission show that 3CsCl.CeCl3.3H2O and CsCl.CeCl3.4H2O have upconversion luminescence of infrared-visible range,and the upconversion emission intensity increases with the increase of ratio of CeCl3 in CsCl.     

RE2O3-Al2O3-SiO2玻璃连接氮化硅合成复相陶瓷的研究

采用Ｙ２Ｏ３－Ａｌ２Ｏ３－ＳｉＯ２－Ｘ稀土玻璃进行氮化硅复相陶瓷的连接。用四点弯曲方法测定不同连接工艺下的连接强度。并对连接界面进行ＳＥＭ、ＥＰＭＡ和ＸＲＤ分析。液相钎料玻璃在界面上与氮化硅反应，形成氮化硅／Ｓｉ２Ｎ２Ｏ／Ｙ（Ｌａ）－Ｓｉａｌｏｎ玻璃／Ｙ（Ｌａ）－Ｓｉａｌｏ玻璃的梯度层界面。接头强度随着保温时间、妆温度的增加，先增后。 在ＹＡＳ钎料中添加氧化镧，可以提高接头的高温强度。ＬａＹＯ３的     

新型长余辉发光材料SrMgSi2O6:Eu2+,Ln3+的制备及性质

采用凝胶-燃烧法合成了系列稀土离子掺杂的Sr0.94MgSi2O6:Eu0.022+,Ln0.043+(Ln=La,Ce,Nd,Sm,Gd,Dy)蓝色长余辉发光材料,用X射线粉末衍射(XRD)、扫描电镜(SEM)、荧光分光光度计等对合成产物进行了分析和表征.结果表明:掺杂了不同稀土离子的SrMgSi2O6:Eu2+,La3+的晶体结构均为网方品系结构;其激发、发射光谱的峰形、峰位基本无变化,激发光谱为一宽带,最大激发峰位于400 nm处,次激发峰佗于415 nm处,发射光谱也为一宽带,最大发射峰位于470 nm附近,是典型的Eu2+的4F5d_4f跃迁导致的,不同之处在于其激发光谱、发射光谱强度及余辉性质有所差别,其中Dy3+是最理想的共掺杂稀土离子,Sr0.94MgSi2O6:Eu0.022+Dy0.043+的余辉时间最长,可达4 h;而Sm3+最差,Sr0.94MgSi2O6:Eu0.022+,Sm0.043+的余辉亮度最低,余辉时间最短.     

Nano-sized carboxylates as anode materials for rechargeable lithium-ion batteries

Nano-sized caiboxylales Na2C7H3NO4 and Na2C6H2N2O4 were prepared and investigated as anode materials for lithium-ion batteries.Both carboxylates exhibit high reversible capacities around 190 mAh/g above a cut-off voltage of 0.8 V vs.Li＋/Li.potentially improving the safety of the batteries.In addition,good rate performance and long cycle life of these carboxylates make them promising candidates as anode materials for lithium-ion batteries.     

Time‐Resolved Phase Transitions of the Nanocrystalline Cubic to Submicron Monoclinic Phase in Mn2O3‐ZrO2

The nanocrystalline cubic phase of zirconia was found to be thermally stabilized by the addition of 3 to 40 mol % manganese. The nanocrystalline cubic, tetragonal and monoclinic phases of zirconia stabilized with manganese (III)oxide (Mn‐Stabilized Zirconia) were prepared by thermal decomposition of carbonate and hydroxide precursors. Both the crystallization and isothermal phase transitions associated with Mn‐SZ were studied using high temperature x‐ray diffraction and x‐ray diffraction of quenched samples. Cubic Mn‐SZ initially crystallized and progressively transformed to tetragonal, and monoclinic structures above 700°C. The nanocrystalline cubic Mn‐SZ containing 25 mol % Mn was found to have the greatest thermal stability, retaining its cubic form at temperatures as high as 800°C for periods up to 25 hours. Higher than 40 mol %, cubic Mn₂O₃ was found to coexist with cubic Mn‐SZ. The crystallite sizes observed for the cubic, tetragonal and monoclinic Mn‐SZ phases ranged from 50 to 137, 130 to 220, and 195 to 450 Å respectively, indicating, for ZrO₂, that particle size was a primary factor in determining its polymorphs. The classical Avrami equation for nucleation and growth was applied to the observed phase transformations.     

石墨相氮化碳负载磷钨酸杂化材料的制备及其氧化脱硫催化性能

以1-丁基-3-甲基咪唑溴离子液体([Bmim]Br)、磷钨酸(H_3PW_(12)O_(40))和g-C_3N_4为原料,采用原位沉淀法合成了负载型[Bmim]_3PW_(12)O_(40)/g-C_3N_4催化剂(BPWO/g-C_3N_4)。通过XRD、FT-IR、UV-vis、氮气吸附、TEM和XPS等手段对催化剂的形貌和结构进行了表征,并以二苯并噻吩(DBT)的正庚烷溶液为模拟油、过氧化氢为氧化剂,考察了各组分负载量、催化剂用量、氧/硫物质的量比(O/S)和反应温度变量等对其氧化脱硫效果的影响。结果表明,BPWO/g-C_3N_4具有Keggin型杂多阴离子结构特征,BPWO (20%)/g-C_3N_4催化剂具有最优的对DBT的氧化脱硫性能,在50℃、O/S物质的量比为6.0的条件下反应180 min,可以完全氧化浓度为800μg/g的含DBT模拟油。同时,该BPWO/g-C_3N_4催化剂具有良好的重复使用性能,循环使用八次后其对DBT的氧化活性没有明显降低。     

N2O在Au/Co3O4和Au/ZnCo2O4催化剂上的分解反应

通过调变HAuCl₄溶液的pH值和Au负载量,用沉积-沉淀法制备了一系列Au/Co₃O₄催化剂,并采用AES、BET、XRD、SEM、XPS和H₂-TPR等技术对催化剂的结构和组成进行了表征,考察了制备条件对其在有氧气氛中催化N₂O分解反应性能的影响规律,得到了催化剂最佳制备条件:HAuCl₄溶液pH值为9,Au负载量为0.29%。催化测试结果表明:虽然ZnCo₂O₄的催化活性优于Co₃O₄,但0.31%Au/ZnCo₂O₄的活性和稳定性低于0.29%Au/Co₃O₄。500℃、在含氧气氛中连续反应10 h, 两者均可完全分解N₂O,但在含氧、含水气氛中0.29%Au/Co₃O₄和0.31%Au/ZnCo₂O₄上的N₂O转化率分别为92%和63%。究其原因,发现Au/Co₃O₄中Au和Co组分间存在协同效应,而Au/ZnCo₂O₄中Au和Co组分间则没有协同效应。     

Time‐Resolved High and Low Temperature Phase Transitions of the Nanocrystalline Cubic Phase in the Y2O3‐ZrO2 and Fe2O3‐ZrO2 System

The nanocrystalline cubic Phase of zirconia was found to be thermally stabilized by the addition of 2.56 to 17.65 mol % Y₂O₃ (5.0 to 30.0 mol % Y, 95.0 to 70.0 mol % Zr cation content). The cubic phase of yttria stabilized zirconia was prepared by thermal decomposition of the hydroxides at 400°C for 1 hr. 2.56 mol % Y₂O₃‐ZrO₂ was stable up to 800°C in an argon atmosphere. The samples with 4.17 to 17.65 mol % Y₂O₃ were stable to 1200°C and higher. All samples at temperatures between 1450°C to 1700°C were cubic except the sample with 2.56 mol % Y₂O₃ which was tetragonal. The crystallite sizes observed for the cubic phase ranged from 50 to 150 Å at temperatures below 900°C and varied from 600 to 800 nm between 1450°C and 1700°C. Control of furnace atmosphere is the main factor for obtaining the cubic phase of Y‐SZ at higher temperature. Nanocrystalline cubic Fe‐SZ (Iron Stabilized Zirconia) with crystallite sizes from 70 to 137 Å was also prepared at 400°C. It transformed isothermally at temperatures above 800°C to the tetragonal Fe‐SZ and ultimately to the monoclinic phase at 900°C. The addition of up to 30 mol % Fe(III) thermally stabilized the cubic phase above 800°C in argon. Higher mol % resulted in a separation of Fe₂O₃. The nanocrystalline cubic Fe‐SZ containing a minimum 20 mol % Fe (III) was found to have the greatest thermal stability. The particle size was a primary factor in determining cubic or tetragonal formation. The oxidation state of Fe in zirconia remained Fe³⁺. Fe‐SZ lattice parameters and rate of particle growth were observed to decrease with higher iron content. The thermal stability of Fe‐SZ is comparable with that of Ca‐SZ, Mg‐SZ and Mn‐SZ prepared by this method.     

固相法合成锂离子电池正极材料LiMn2O4

用Li2CO3和Min(OAc)2@4H2O为锂锰源,添加少量柠檬酸或草酸在550℃煅烧4h合成了尖晶石LiMn2O4.采用X-射线衍射法,透射电镜和充放电测量研究了它们的结构和性质.用Scherre公式计算样品粒度在28.5nm～40.0nm.添加草酸制备的样品充放电性能较好,首次充放电的放电容量可达115mAhg-1.     

A novel mechanism for the isomerization of N2O4 and its implication for the reaction with H2O and acid rain formation

We have discovered, by high‐level quantum‐chemical calculations, a new and predominant isomerization mechanism for N₂O₄ → ONONO₂ via a roaming‐like transition state occurring unimolecularly or bimolecularly during collision with H₂O. The new mechanism allows N₂O₄ to react with H₂O with a significantly lower barrier (< 13.1 kcal/mol) than the commonly known tight transition state (∼30‐45 kcal/mol) by concurrent stretching of the N N bond and rotation of one of the NO₂ groups to form trans‐ONONO₂, which then undergoes a rapid metathetical reaction with H₂O in the gas phase and in aqueous solution. The results have a significant implication for the hydrolysis of N₂O₄ in water to produce HONO and HNO₃. Rate constants for the isomerization and hydrolysis reactions have been predicted for atmospheric modeling applications.     

不同沉淀剂对Co3O4催化剂催化分解N2O活性的影响

采用了不同沉淀剂（K2 CO3、Na2 CO3、NaOH、NaHCO3）制备了一系列 Co3 O4氧化物催化剂。通过 XRD、XPS、BET、H2-TPR、O2-TPD 表征手段,探究了催化剂物相结构和氧化还原性能对 N2 O 催化分解性能的影响。研究表明,以 K2 CO3为沉淀剂制备的 Co3 O4催化剂具有优越的氧化还原性能。此外,较低结晶度有助于提高催化剂的催化性能,催化剂表面物种与其沉淀剂相关：丰富的表面 Co 物种促进催化活性,较多氧空位有利于催化剂表面的电子传递和氧气的脱附。以 K2 CO3为沉淀剂制备的 Co3 O4催化剂表现出最佳的 N2 O 催化分解活性,在450℃达到90％以上的转化率。     

硫酸铯/聚乙二醇双水相体系在298.15K的相平衡

水溶性高聚物的双水相体系可用于纯化一些无机盐,获得高纯晶体。由于高聚物的存在会减小盐在溶液中的溶解度,从而可能析出晶体。本文采用自制的相平衡装置,测定了硫酸铯／聚乙二醇(PEG1000,4000,10000)双水相体系在298．15K时的等温平衡溶解度。     

In situ Hochdruck- und Hochtemperatur-Untersuchungen an Siliciumsuboxiden mittels energiedispersiver Röntgenbeugung

In situ High-Pressure- and High-Temperature Studies of Siliconsuboxides via Energy Dispersive X-ray Diffraction The amorphous silicon compounds Si₂O₃, H₂Si₂O₄, HSiO_1.5, and SiO have been investigated under High-Pressure- and High-Temperature conditions in situ via energy dispersive X-ray diffraction with synchrotron radiation. The studies have been performed using the Multi Anvil High Pressure Device MAX-80, at HASYLAB, DESY-Hamburg, Germany. Except for SiO, at a pre-set pressure of 45 kbars the formation of Coesite was observed at heating. Commercially available SiO did not crystallize in any way, indicating that it seems not to consist of silicon(II)-oxide, but is in fact a mixture of silicon and silicondioxide, disproportionated on an atomic scale.