Preparation, physico-chemical behavior and catalytic property for ammonia oxidation of perovskite like mixed oxides La2-xSrxCuO4-lambda

A series of Sr2+ doped perovskite like oxides La2-xSrxCuO4-lambda (x = 0 similar to 1) were prepared, the structure, lattice parameters, content of Cu3+, oxygen vacancies created by Sr2+ substitution and composition of these complex oxides were studied by XRD and iodic titration method. The redox ability,active oxygen species and surface image were evaluated and analyzed with TPD, TG, XPS and SEM measurements. The catalytic activity for ammonia oxidation over these oxides was tested, and the relationship among the catalytic properties, structure, nonstoichiometric oxygen,redox ability and surface behavior were correlated and some information on the mechanism of ammonia oxidation was obtained.

The effect of some factors on the electric properties of rare earth complex oxide

The rare earth complex oxides with different types have been synthesized. Their structures and electric properties have been investigated. According to our experimental results, the effects of the outest shell electronic configuration, electron spin state, electron transport path and formation of cluster on the electric properties of rare earth complex oxides have been summarized. When the electrons in the outest shell of the central metallic ion are unpair, and the outest shell is not half-filled, the electric conductibilities of these compounds are better, If there is a -M-X-M-X- or -M-M-M- (the distances between two atoms <0.31 nm) continuous electron transport path, and the electron configurations of the central metallic ion conform to the above condition, then the electric conductibilities are good, The isolate cluster can not become the continuous electron transport path, therefore, the formation of the isolate cluster will reduce the conductibility.

X-Ray Photoelectron Spectroscopy Study of LaMn1-xFexO3 (x=0-1) Oxides

The redox potential, surface composition and oxygen species of a series of complex oxides LaMn1-xFexO3 (x=0-1) having perovskite structure (ABO(3)) have been investigated by means of XI'S. The variation of binding energies referring to Mn2p and Fe 2p under different treatment offerred an obvious evidence of redox between Mn and Fe, which could be expressed as Mn4+ + Fe(3-delta)+ Mn(4-delta)+ Fe3+ Feat Through computer fit three kinds of adsorbed oxygen species (O-I, O-II, O-III) have been evaluated based on the XPS spectra of O1s. From the variation of contents of different oxygen species, it could be concluded that. the redox occuring in the surface might be related with the adsorbed oxygen species O-I and O-II, furthermore the possibility of transfer of electron between adsorption site and oxygen was also discussed.

稀土与钼复合氧化物的合成、结构和电性质研究

固体氧化物燃料电池（SOFC）被称为“二十一世纪的绿色能源”。氧化忆稳定氧化错（YSZ）是目前sOFC普遍采用的固体电解质材料。由于YSZ只有在高温时（大于1000℃）才具有较高的离子导电性，而SOFC在高温时会带来一系列技术性的问题，如机械强度的不稳定、材料的老化及各构成材料之间的相互扩散等。因此，迫切需要开发在中、低温范围内（600-800℃）具有较高离子电导率（大于10-2S．cm-l）的电解质材料。在众多的候选材料中，稀土作为基体和掺杂元素的固体电解质越来越引起人们的重视。特别是萤石型化合物CeOZ、钙钦矿型化合物LaGaO3，以及阴离子空位型化合物La2MO2O9等的研究，开阔了寻找固体电解质材料的视野。本论文主要研究稀土与钥复合氧化物的合成、结构及其电学性质，希望进一步提高现有材料的导电性能和寻找新型固体电解质材料。基于母体化合物La2Mo2O9在580℃左右有一个相变点，因为存在相变点的固体电解质在实用方面（如SOFC）有很大的局限性。我们从稀土掺杂的角度出发，对母体化合物进一步改性，稳定其高温结构相。为此，我们利用改性柠檬酸盐法合成了系列化合物La2-xRExMo2O9（RE＝Ce，Pr，Nd，Sm，Gd，Tb，Dy，Ho，Er，Yb）。结果发现，只有Nd和Sm可以进入La2Mo2O9中La的格位；利用本方法合成样品的温度比用固相法低250℃左右；所合成的样品粒度分布非常均匀，并且随着Nd和Sm掺杂量的增加而变大；Nd和Sm的掺杂稳定了其高温相，电导率有所提高。从而使此类固体电解质在实用方面成为可能。合成了一种新型稀土与钥的复合氧化合物Ce6MoO15，电学性质测试发现，它是一性能优良的固体电解质材料。以此化合物为母体）进行低价金属离子的掺杂取代后发现，它们的导电性又进一步地提高，进而派生出多种固体电解质体系如Ce6-6 MoO15-δ、Ce6+x Mo1-x O15-6、Ce6Mo1-xBixO16-6以及Ce6-xAxMoO15-6。（A＝Li，Ca，Sr和Ba）等。本研究工作中主要合成了Ce6-xRExMoO16-6（RE=Pr，Nd，Sm，Gd，Tb，Dy，Ho，Er，Yb；x=0.0-6.0）等系列化合物，并对其进行了结构表征及电学性质测试。结果发现所有样品均为类莹石结构；样品的导电性起源于氧离子空位；在相同的温度下，样品电导率相当于或高于经典的固体电解质（如YSZ），并且样品的抗老化性能有所提高。所有这些实验事实证明，它们在中温区是一种高效氧离子导体，从而为此类化合物在SOFC中的应用奠定了基础。通过合成AgScMo2O8，尝试了一种钥酸盐固溶体的合成方法，即钥酸盐水溶液合成法。这种方法不需要加入有机物（如柠檬酸等）作为络合剂，而是通过钼酸根与金属离子之间的酸碱对效应直接合成。我们对此化合物的结构、电学性质进行研究后发现：此化合物在较低的温度即已完全成相；室温下，Agsco208为单斜结构，不同于AgLnMo2O8（Ln＝Y-Lu）；随着温度的升高，AgscMo2o8在485℃、539℃附近各有一个不可逆，可逆相变点出现。在可逆相变点出现的同时，伴随着其电导率有一个很大的突跃。

Phase behavior of rare earth manganites

Among complex oxides containing rare earth and manganese BaLn(2)Mn(2)O(7)( Ln = rare earth) with the layered perovskite type and Ln(2)(Mn, M)O-7 with pyrochlore-related structure were studied since these compounds show many kinds of phases and unique phase transitions. In BaLn(2)Mn(2)O(7) there appear many phases, depending on the synthetic conditions for each rare earth. The tetragonal phase of so-called Ruddlesden-Popper type is the fundamental structure and many kinds of deformed modification of this structure are obtained. For BaEu2Mn2O7 at least five phases have been identified from the results of X-ray diffraction analysis with the space group P4(2)/mnm, Fmmm, Immm and A2/m in addition to the fundamental tetragonal I4/mmm phase. In the pyrochlore-related type compounds, Ln(2)Mn(2-x)M(x)O(7)(M = Ta, Nb, W etc), there also appear several phases With different crystal structures. With regard to every rare earth, Ln(2)MnTaO(7) phase is stable only for excess Ta and can be obtained under high oxygen partial pressure process. This group has trigonal structure with zirkelite type ( P3(1)21 space group).

Studies of methane reforming with carbon dioxide on hexaaluminates

In this paper, a series of Sr1-xLaxNiAl11O19 catalysts were synthesized and their chemical and physical properties were investigated by XRD, UV-DRS, H-2-O-2 titration, TPR and Py-IR techniques. The experimental results show that the Sr1-xLaxNiAl11O19 catalysts have a magnetoplumbite structure and Ni ion is shared between tetrahedral and octahedral sites of the spinel blocks, and the amount of nickel ions in the tetrahedral environment increases with the increase of x value in Sr1-xLaxNiAl11O19. The TPR study revealed that the reducibility of the series of the catalysts depends strongly on the substitution value x, that is, a low temperature peak appears for samples without substitution, in case of samples with x = 1 high temperature peak appears, and for samples with 0complex oxides catalysts.

THE YELLOW-TO-BLUE INTENSITY RATION (Y/B) OF DY-3+ EMISSION

Various borates, vanadates, niobates, antimonates, titanates, zirconates and CaS doped with Dy3+ were prepared. Factors which have an effect on the yellow-to-blue intensity ratio (Y/B) of Dy3+ emission are reported. Y/B increases with decreasing Z/r or electronegativity of the next-neighbour element M in the complex oxides Dy-O-M. The greater the degree of covalency between Dy3+ and O2-, the greater Y/B is. When Dy3+ is located at a site with an inverse centre and high symmetry, Dy3+ displays no luminescence. It seems that Y/B of Dy3+ located at a site deviated from an inverse centre is greater than that of Dy3+ located at a site without an inverse centre. Y/B does not vary much with the variation in concentration of Dy3+ when Dy3+ is substituted for an element with the same valency, but it does depend on the concentration of Dy3+ when Dy3+ is substituted for an element with a different valency in the matrix, because defects are formed in this case.

Erbium-Complex-Doped Near-Infrared Luminescent and Magnetic

A near-infrared luminescent macroporous material (PL-Macromaterial) and a near-infrared luminescent/magnetic bifunctional macroporous material (MML-Macromaterial) were synthesized by using polystyrene microspheres (PS) and Fe3O4 @polystyrene core-shell nanoparticles (Fe3O4@PS), respectively, as templates. Both the PL-Macromaterial and the M/PL-Macromaterial show the characteristic emission of the Er 3, ion. Moreover, the M/PL-Macromaterial possesses superparamagnetic properties at room temperature.

Complex aggregates of spherical colloids via modified micromolding in capillaries

This paper describes a simple approach to fabricate aggregates composed of monodispersed silica microspheres by modified micromolding in capillaries (MIMIC). Two different kinds of contact modes, namely, conformal contact and non-conformal contact, between the poly(dimethylsiloxane) (PDMS) mold and the underlying prepatterned substrate, can be controlled during the micromolding, which result in the formation of different aggregates under the influence of template confinement and capillary forces. These aggregates, including woodpile structure, discoid, conoid and rectangular clusters, possess well-controlled sizes and orientation. The possible mechanisms for the formation of different aggregates are discussed in detail.

A novel 2D arsenic vanadate network grafted with a transition metal complex: [Cu(phen)][(VV4As2O19)-V-IV-As-V]center dot 0.5H(2)O

A novel organic-inorganic hybrid compound [Cu(phen)](2)[(VV4As2O19)-V-IV-As-V-O-V].0.5H(2)O 1 has been hydrothermally synthesized. Its structure, determined by single crystal X-ray diffraction, exhibits an unusual two-dimensional arsenic vanadate layered network grafted with the [Cu(phen)](2+) complex. The chelating phen ligands project perpendicularly beyond the inorganic layer. Variable temperature magnetic susceptibility studies indicate that both ferro- and antiferro-magnetic interactions exist in 1.

Hydrothermal synthesis and characterization of bimetallic cluster complex [{Mn(phen)(2)}(2)V4O12]center dot 1/2 H2O

A new bimetallic cluster complex with the formula [(Mn(phen)(2))(2)V4O12].1/2 H2O has been synthesized through hydrothermal reaction of vanadate staring material with manganese cation in the presence of nitrogen donor chelating ligand and characterized by single-crystal X-ray diffraction, elemental analysis, IR UV-vis, ESR spectrum and thermal analysis. The compound crystallize in the monoclinic space group P2(1)/c with a = 18.475(4) Angstrom, b = 11.473(2) Angstrom, c = 23.667(5) Angstrom, beta = 97.76(3)degrees, V = 4971(2) Angstrom(3) and Z = 4. The structure of [{Mn(phen)(2)}(2)V4O12].1/2 H2O is composed of a discrete V4O124- cluster covalently attached to two [Mn(phen)(2)](2+) fragments.

The electrical and magnetic properties of lanthanide alkaline-earth transition-metal oxides

Five Ln(2)SrMCuO(6.5) oxides (M = Co, Ln = Y and Ho; M = Fe, Ln = Y, Ho, and Dy) were synthesized, and their crystal structures, IR spectra, and physical properties were studied. They have almost the same structure and crystallize in orthorhombic systems. Below room temperature, Y2SrFeCuO6.5, a known layered oxide, shows antiferromagnetic behavior, but the four new oxides are paramagnetic. Y2SrFeCuO6.5 fits the Curie-Weiss law in the temperature range 300-100 K, but Y2SrCoCuO6.5 shows complex magnetic behavior because of the disproportion of some Co+3 to Co+2 and Co+4 The five oxides are all p-type semiconductors in the measured temperature range and have large electrical resistivities at room temperature.

Semiempirical method for the evaluation of bond covalency in complex crystals

We report a semiempirical method for the evaluation of bond covalency in complex crystals. This method is the extension of the dielectric description theory delivered by Phillips, Van Vechten, Levine, and Tanaka (PVLT) which is mainly suitable for binary crystals. Our method offers the advantage of applicability to a broad class of complex materials. The simplicity of the approach allows a broader class of researchers to access the method easily and to calculate not only the bond covalency but also other useful. properties such as bulk modulus. For a series study, a useful trend can be illustrated and often the prediction of the properties of the-missing one(s) among the series can be possible. Finally, examples are given to show how the method is applied and the procedure is transferable to other complex crystals.

Activation of a ring methyl substituent in pentamethylcyclopentadienyl rhenium(V) compounds: Synthesis and characterization of the 1,2,3,4-tetramethyl-5,6-dihydrofulvene-5,6-dithiolato complex [ReO{(S)(SCH2)C(5)Me(4)}(C(5)Me(5))]

Reaction of the half-sandwich rhenium(v) complexes [Re-Cl-4(C(5)Me(5))] or [Re(O)Cl-2(C(5)Me(5))] with H2S in chloroform in the presence of pyridine leads to the chiral dithiolato complex [ReO((S)(SCH2)C(5)Me(4))(C(5)Me(5))] 1.

STRUCTURE AND CATALYTIC ACTIVITY FOR PROPYLENE OXIDATION OF BI-MO-NB COMPLEX OXIDE CATALYSTS

The structure and catalytic,activity for propylene oxidation of series oxides B2Mo3-3X-Nb2XO12-4X (X=0.00, 0.02, 0.05, 0.10, 0.15, 0.20, 0.25) have been studied by means of XRD, IR, Raman, SEM, ESR and so on. The results showed that in the range of X < 0.