LaCaMnO3催化剂活性相的结构和形成机理的研究

利用ＴＧ，ＤＴＡ，ＸＲＤ和ＸＰＳ方法研究了Ｌａ０．２Ｃａ０．８ＭｎＯ３催化剂的结构和形成机理。样品用Ｌａ，Ｃａ，Ｍｎ混合硝酸盐制备。随着焙烧温度的升高发生的一系列的固相反应，发现氨氧化催化剂催化活性与生成的ＣａＭｎＯ３含量成正比。在９００℃制备的含有ＣａＭｎＯ３，Ｌａ０．５７５Ｃａ０．４２５ＭｎＯ３，Ｍｎ２Ｏ３和Ｌａ２Ｏ３的混合物是氨氧化最佳催化剂，活性相是ＣａＭｎＯ３，并具有大量的氧空穴。     

Some new Schiff base ligands giving a NNOS coordination sphere and their nickel(II) complexes: Synthesis,characterization and complex formation

Some new tetradentate ligands with a NNOS coordination sphere were prepared and their corresponding nickel(II) complexes were synthesized and characterized by elemental analysis, IR, ¹H NMR, UV–Vis and mass spectrophotometry. The thermodynamic formation constants of the complexes were measured spectrophotometrically, at a constant ionic strength of 0.1 M (NaClO₄) at 25 °C in DMF solvent. The trend of the complex formation for nickel is as follows:     

线团式纳米NaY分子筛复合材料的制备及形成机理

通过在偏高岭土水热合成NaY分子筛的晶化过程中加入乙醇的方法,制备了线团式纳米NaY分子筛复合材料,用XRD、SEM、ICP OES研究了晶化过程中固液相结构和组成的变化,初步探讨了其形成机理,提出了制备纳米NaY分子筛复合材料的条件.     

Die Ammonolyse von (NH4)2GeF6. Darstellung und Struktur von NH4[Ge(NH3)F5]

Ammonolysis Reaction of (NH₄)₂GeF₆. Synthesis and Structure of NH₄[Ge(NH₃)F₅] (NH₄)₂GeF₆ reacts with ammonia to yield NH₄[Ge(NH₃)F₅] at 280°C. The reaction path was elucidated by in situ time and temperature resolved X-ray powder diffraction. NH₄[Ge(NH₃)F₅] crystallizes isostructurally to NH₄[Si(NH₃)F₅] in the tetragonal space group P4/n (No. 85) with lattice constants a = 619.41(1) pm and c = 724.70(1) pm. The germanium atom is coordinated by five fluorine atoms and the nitrogen atom of the ammonia molecule. The ammonium cation is located on the Wyckoff position (2 a) in P4/n. The crystal structure is stabilized by extensive hydrogen bonding.     

Calculation of the formation energies of isolated vacancy and adatom-vacancy pair at low-index surfaces of fcc metals with MAEAM

The formation energies of isolated vacancy and adatom-vacancy pair (where the two are separated by a large distance) at low-index surfaces of fcc metals calculated by using the modifies analytical embedded atom method (MAEAM). The results predict the prevailing formation of vacancies on the surfaces (1 1 1), (1 0 0) (but Pd), Cu and Ni on the (1 1 0) surfaces at low temperature, and the defect formation energies consistently create in the sequence (1 1 0) → (1 0 0) → (1 1 1). With good accuracy, the calculated energy values coincide with those obtained by the embedded atom methods (EAM) and from experiments. The correctness of the method by which calculated the formation energies of point defects on the surface was proved.     

Thermodynamic analysis of the shape, anisotropy and formation process of InAs/InP(0 0 1) quantum dots and quantum sticks grown by metalorganic vapor phase epitaxy

This study describes the origin of the size and shape anisotropy of InAs/InP(0 0 1) quantum dots (QDs) grown by metalorganic vapor phase epitaxy (MOVPE). The geometry of the QDs is determined by carefully analyzing transmission electron microscopy (TEM) images. An analytical model adapted to our QD geometry is used to understand the formation mechanism of the QDs, and to describe the origin of their size dispersion. A shape transition from QDs to elongated quantum sticks (QS) is observed under As-poor growth conditions. This transition, driven by thermodynamics, is clearly described by our model.     

A two-dimensional CA model for traffic flow with car origin and destination

Dynamic phase transitions in a two-dimensional traffic flow model defined on a decorated square-lattice are studied numerically. The square-lattice point and the decorated site denote intersections and roads, respectively. In the present model, a car has a finite deterministic path between the origin and the destination, which is assigned to the car from the beginning. In this new model, we found a new phase between the free-flow phase and the frozen-jam phase that is absent from previous models. The new model is characterized by the persistence of a macroscopic cluster. Furthermore, the behavior in this macroscopic cluster phase is classified into three regions characterized by the shape of the cluster. The boundary of the three regions is phenomenologically estimated. When the trip length is short and the car density is high, both ends of the belt-like cluster connect to each other through the periodic boundary with some probability. This type of cluster is classified topologically as a string on a two-dimensional torus.     

NTO及其铷盐水溶液光谱研究

用Raman光谱和FTIR光谱对NTO晶体和不同pH值的水溶液以及配合物Rb(NTO)·H₂O的水溶液进行了研究。从已测定的单晶结构表明金属离子与NTO-的CNO,CO基团和水分子中的氮、氧原子键合。Raman和FTIR光谱特征的主强峰也表明是在NTO-的CNO₂和CO基团的氧和氮原子与金属离子形成弱配位键。该配合物饱和水溶液的振动光谱峰与晶体的振动光谱峰基本上吻合。表明该配合物在水中键合未发生变化,因而NTO的碱金属配合物在水溶液中的振动光谱峰归属可以用晶体中键的形成来说明。讨论了金属离子与NTO必需在碱性水中才能形成NTO的金属配合物机理。     

聚合物锂离子电池不同化成电压下产生气体的研究

应用气相色谱方法初步探讨了聚合物锂离子电池在首次充电过程中于不同化成电压下产生气体的原因和机理.结果表明,当电池电解液采用1mol/LLiPF6-EC～DMC～EMC(三者体积比1∶1∶1)时,于化成电压小于2.5V下,产生的气体主要为H2和CO2等;化成电压为2.5V时,电解液中的EC开始分解,电压在3.0～3.5V的范围内,由于EC的还原分解,产生的气体主要为C2H4;而当电压大于3.0V时,由于电解液中DMC和EMC的分解,除了产生C2H4气体外,CH4,C2H6等烷烃类气体也开始出现;电压高于3.8V后,DMC和EMC的还原分解成为主反应.此外,当化成电压处于3.0～3.5V之间,化成过程中产生的气体量最大;电压大于3.5V后,由于电池负极表面的SEI层已基本形成,因此,电解液溶剂的还原分解反应受抑制,产生的气体的数量也随之迅速下降.