化学气相传输法制备无水稀土氯化物

以化学气相传输法制取无水EuCl3,ErCl3和LuCl3。稀土氧化物为原料 ,无水氯化铝为氯化剂和传输介质。Ln2 O3与过量的氯化铝在3 0 0℃反应 ,生成LnCl3。LnCl3在高温与氯化铝反应生成气态配合物 ,该配合物在低温分解。控制适当的温度梯度场 ,可实现LnCl3与其他固体分离。残余氯化铝在 2 0 0℃加热除去。产物收率 >90 % ,纯度 >99 5%。利用化学气相传输法可获得纯度较高的无水LnCl3。     

化学气相传输法分离二元混合重稀土氧化物

稀土气态配合物;化学气相传输法分离二元混合重稀土氧化物     

稀土气态配合物PrAl3Cl12的热力学研究

用 对氯化镨与氯化铝形成气态配合物的反应（ＰｒＣｌ３（ｓ）＋（ｘ／２）Ａｌ２Ｃｌ６（ｇ）＝ＰｒＡｌｘＣｌ３ｘ＋３），进行了研究，实验显示，在６０４－８８２７Ｋ、０．０５－０．１５ＭＰａ条件下，ＰｒＡｌ３Ｃｌ１２配合物是唯一产物。测定了配合物的稳定常数，计算了反应的焓变和熵变，并讨论了其误差。     

稀土气态配合物REAl_3Br_(12)稳定性规律

采用骤冷法对反应REBr3(s)+(3/2)Al2Br6(g)=REAl3Br12(g)进行研究,实验温度和压力范围分别是600~850 K和0.0077~0.22 MPa,反应平衡时间为6 h。测定它们在不同温度下的稳定常数。结果显示,中稀土的气态配合物稳定常数最大。以气态配合物REAl3Br12的lgKp与Z+/r作图,可将镧系稀土元素分为La-Eu,Eu-Er和Er-Lu三组,在每一组内,REAl3Br12的稳定常数均呈线性关系。在稀土气态配合物RE-Al3Br12稳定常数与原子序数及离子势(Z+/r)的变化关系中都存在着钆断现象。REAl3Br12稳定常数的对数值对RE(Ⅲ)的基态角量子数作图,得到四条直线,类似斜W效应。     

铈和硫代脯氨酸、水杨酸三元配合物的热化学性质

用七水合氯化铈与硫代脯氨酸(C4H7NO2S)和水杨酸(C7H6O3)合成了三元固体配合物[Ce(C7H5O3)2(C4H6NO2S)]·2H2O。根据盖斯定律设计一个热化学循环,用恒温环境的溶解―反应量热法研究得到合成反应的标准反应焓为263.12±0.95 kJ/mol,进而算出配合物298.15 K时的标准摩尔生成焓为-2785.7±3.2 kJ/mol。     

氟碳铈矿-独居石混合精矿碳热氯化反应

研究了氟碳铈矿-独居石混合精矿的高温氯化反应, 发现在活性脱氟剂存在下, 在500～800 ℃之间, 稀土氯化率由无脱氟剂时的55%～88%增至92%～99%. 当氯化反应温度低于600 ℃时, 氯化产物的酸不溶物的量随着温度的升高而降低; 而当温度高于900 ℃时, 酸不溶物的量明显增加. 脱氟剂的作用可以使氟碳铈矿-独居石混合精矿氯化反应在600 ℃的低温下进行, 这和1000～1200 ℃的Goldschmidt加碳氯化工艺明显不同.     

稀土气态配合物GdAl3Br12的热力学研究

通过骤冷法实验, 在622～770 K的温度范围和0.0075～0.18 Mpa的压力范围内, 对气态配合物GdAlxBr3x 3的形成热力学进行了探讨. 结果显示, 溴化钆与气态溴化铝二聚体生成唯一产物GdAl3Br12气态配合物; 反应GdBr3(s) (1/2) Al2Br6(g)=GdAl3Br12 (g)的平衡常数、焓变和熵变, 通过骤冷法实验和计算得出.     

三元配合物Yb[(C5H8NS2)3(C12H8N2)]的热化学性质研究

在无水乙醇中, 用吡咯烷二硫代氨基甲酸铵(APDTC)和1, 10-邻菲咯啉(o-phen·H2O)与YbCl3·3.84H2O作用, 合成了三元固态配合物, 确定它的组成为Yb[(C5H8NS2)3(C12H8N2)]. 用RD496-Ⅲ微量热计测定了298.15 K下水合氯化镱及两个配体在无水乙醇中的溶解焓, 两个配体醇溶液的混合焓及不同温度下标题化合物液相生成反应的焓变; 得到了液相生成反应的热力学参数(活化焓、活化熵和活化自由能)和动力学参数(速率常数、表观活化能、频率因子和反应级数); 通过合理的热化学循环, 求得了298.15 K时标题化合物的固相生成反应焓变; 推导了用该热量计测定固态物质比热容的计算式, 并测定了该配合物298.15 K的比热容.     

配合物[Sm(C7H5O3)2(C4H6NO2S)]·2H2O的热化学研究

将六水氯化钐,水杨酸与硫代脯氨酸3种物质一起反应,制得了一种新的稀土三元固体配合物[Sm(C7H5O3)2(C4H6NO2S)].2H2O(s)。通过红外光谱、热重差热分析、元素分析等手段确定了其结构与组成。在常压、298.15 K下,分别测定了六水氯化钐、水杨酸、硫代脯氨酸和该配合物在混合溶剂(二甲亚砜∶乙醇∶3 mol.L-1HCl=1∶1∶1)中的溶解焓,并根据热化学原理得出了298.15 K时配合物[Sm(C7H5O3)2(C4H6NO2S)].2H2O(s)的标准摩尔生成焓ΔfHmΘ=(-2913.73±3.10)kJ.mol-1。     

三元配合物Tb(Et2dtc)3(phen)的热化学性质

以铜试剂(NaEt2dtc•3H2O)和邻菲咯啉(o-phen•H2O) 与水合氯化铽(TbCl3•3.75H2O)在无水乙醇中制得了三元固态配合物.化学分析和元素分析确定其组成为Tb(Et2dtc)3(phen).IR光谱研究表明配合物中Tb3＋与NaEt2dtc中的硫原子双齿配位,同时与phen的氮原子双齿配位.用Calvet微热量计测定了298.15 K下液相生成反应的焓变ΔrHmθ(l),为(－21.819±0.055) kJ•mol－1,通过热化学循环计算了固相生成反应焓变ΔrHmθ(s),为(128.476±0.675) kJ•mol－1.改变反应温度,研究了液相生成反应的热动力学.用精密转动弹热量计测得配合物的恒容燃烧能ΔcU为(－17646.95±8.64) kJ•mol－1,经计算其标准燃烧焓ΔcHHmθ和标准生成焓ΔfHmθ分别为(－17666.16±8.64) kJ•mol－1和(－1084.04±9.49) kJ•mol－1.     

Two Step Chemical Vapor Deposition of In2Se3/MoSe2 van der Waals Heterostructures

Two-dimensional transition metal dichalcogenides heterostructures have stimulated wide interest not only for the fundamental research,but also for the application of next generation electronic and optoelectronic devices.Herein,we report a successful two-step chemical vapor deposition strategy to construct vertically stacked van der Waals epitaxial In₂Se₃/MoSe₂ heterostructures.Transmission electron microscopy characterization reveals clearly that the In₂Se₃ has well-aligned lattice orientation with the substrate of monolayer MoSe₂.Due to the interaction between the In₂Se₃ and MoSe₂ layers,the heterostructure shows the quenching and red-shift of photoluminescence.Moreover,the current rectification behavior and photovoltaic effect can be observed from the heterostructure,which is attributed to the unique band structure alignment of the heterostructure,and is further confirmed by Kevin probe force microscopy measurement.The synthesis approach via van der Waals epitaxy in this work can expand the way to fabricate a variety of two-dimensional heterostructures for potential applications in electronic and optoelectronic devices.     

Water‐Assisted Vapor Deposition of PEDOT Thin Film

The synthesis and characterization of poly(3,4‐ethylenedioxythiophene) (PEDOT) using water‐assisted vapor phase polymerization (VPP) and oxidative chemical vapor deposition (oCVD) are reported. For the VPP PEDOT, the oxidant, FeCl₃, is sublimated onto the substrate from a heated crucible in the reactor chamber and subsequently exposed to 3,4‐ethylenedioxythiophene (EDOT) monomer and water vapor in the same reactor. The oCVD PEDOT was produced by introducing the oxidant, EDOT monomer, and water vapor simultaneously to the reactor. The enhancement of doping and crystallinity is observed in the water‐assisted oCVD thin films. The high doping level observed at UV–vis–NIR spectra for the oCVD PEDOT, suggests that water acts as a solubilizing agent for oxidant and its byproducts. Although the VPP produced PEDOT thin films are fully amorphous, their conductivities are comparable with that of the oCVD produced ones.

     

叠氮二氢硼多聚体结构和性质的理论研究(英文)

本文采用DFT-B3LYP方法,以不同基组对叠氮二氢硼多聚体(H2BN3)n (n=1-4)进行计算研究.二聚体(H2BN3)2(C2h对称性)中含B2N2平面四元环结构.船式(Cs对称性)和椅式(C3v对称性)三聚体(H2BN3)3的结合能相近(-122 和 -126 kJ·mol-1),其中均含B3N3六元环结构.拥有B4N4八元环结构的四个四聚体的结合能只有稍微差别.与单体相比,簇合物的结构参数变化较大.由ΔG0T可知,298.2 K下单体形成二聚体在热力学上是不利的,而形成三聚体和四聚体是有利的.     

Modeling of the elementary gas-phase reaction during chemical vapor deposition of silicon carbide from CH3SiCl3/H2

We established a gas-phase, elementary reaction model for chemical vapor deposition of silicon carbide from methyltrichlorosilane (MTS) and H₂, based on the model developed at Iowa State University (ISU). The ISU model did not reproduce our experimental results, decomposition behavior of MTS in the gas phase in an environment with H₂. Therefore, we made several modifications to the ISU model. Of the reactions included in existing models, 236 were lacking in the ISU model, and thus were added to the model. In addition, we modified the rate constants of the unimolecular reactions and the recombination reactions, which were treated as a high-pressure limit in the ISU model, into pressure-dependent rate expressions based on the previous reports (to yield the ISU+ model), for example, H₂(+M) → H + H(+M), but decomposition behavior remained poorly reproducible. To incorporate the pressure dependencies of unimolecular decomposition rate constants, and to increase the accuracies of these constants, we recalculated the rate constants of five unimolecular decomposition reactions of MTS using the Rice-Ramsperger-Kassel-Marcus method at the CBS-QB3 level. These chemistries were added to the ISU+ model to yield the UT2014 model. The UT2014 model reproduced overall MTS decomposition. From the results of our model, we confirmed that MTS mainly decomposes into CH₃ and SiCl₃ at the temperature around 1000°C as reported in the several studies.     

直链小碳簇Cn(n=3～6)微正则解离速率常数的RRKM理论计算(Ⅰ)

用从头计算法研究小碳簇的解离通道及其动力学.以MP2/6-31G^*精度优化直链C₃,C₄,C₅,C₆及其过渡态的结构,并对它们进行振动分析.在此基础上计算了各解离通道的能垒,并根据RRKM理论估算各个通道的微正则解离速率.计算结果表明,这些小碳簇的解离主要表现为均裂方式.     

Methane elimination from n‐pentane

The quantum chemical calculations at the different levels of theory were performed with the target being to determine the vibration frequencies and to estimate the barriers to internal rotations of n‐pentane molecules. In connection with the observed losses of CH₃ and CH₄ from the n‐pentane in gas phase, the calculations at the B3LYP level of theory with the 6‐31G(d) basis set were used to study the ground‐state potential energy surface of the n‐pentane. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009     

Interface formation of Al2O3 on n‐GaN(0001): Photoelectron spectroscopy studies

Al₂O₃ insulator layers were deposited step by step by the physical vapor deposition (PVD) method onto gallium nitride in the wurtzite form, n‐type and (0001)‐oriented. The substrate surface and the early stages of Al₂O₃/n‐GaN(0001) interface formation were characterized in situ under ultra‐high vacuum conditions by X‐ray and ultraviolet photoelectron spectroscopy (XPS, UPS). The electron affinity (EA) of the substrate cleaned by annealing was 3.6 eV. Binding energies of the Al 2p (76.0 eV) and the O 1s (532.9 eV) confirmed the creation of the Al₂O₃ compound in the deposited film for which the EA was 1.6 eV. The Al₂O₃ film was found to be amorphous with a bandgap of 6.9 eV determined from the O 1s loss feature. As a result, the calculated Al₂O₃/n‐GaN(0001) valence band offset (VBO) is ?1.3 eV and the corresponding conduction band offset (CBO) 2.2 eV.     

铜簇Cun-和羰基铜簇CunCO-(n=2～7)的结构与光谱性质的密度泛函理论研究

应用相对论有效核势密度泛函理论计算方法研究了Cun-和CunCO-簇的平衡几何构型、稳定性、主要碎片化模式、CO吸附能及其团簇的光谱性质.计算结果表明,奇数簇Cun-的电离势比其相邻偶数簇Cun-的电离势大;奇数的Cu5CO-簇有最大的CO解离能.奇数铜簇阴离子相对较高的稳定性与近似浆汁模型的8电子电子闭壳层效应一致.计算得到的Cun-簇碎片化能量表明,较小Cun-的优势解离通道与其包含Cu原子数目的奇偶性有关,偶数的Cun-簇主要解离为Cu原子和Cun-1-,而奇数Cun-簇易以解离成铜的二聚物Cu2和Cun-2-.基于密度泛函理论计算,讨论了这些簇的静态极化率和CO吸附性质与簇大小的关系.     

An Optical Density Thermometer

Abstract

An optical density thermometer is described for determining the temperature of centrifuge rotors. Quantitation is based on the change in the concentration of the vapor phase of a volatile substance, such as bromine, with temperature. Centrifugal force holds the liquid phase away from the light path and removes condensation from the optical windows.