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1.
Solvent extraction studies have been made on some metals: In/III/-Tl/III/ and Hg/II/-Cd/II/-Co/II/, from ammonium thiocyanate solutions by dialkyl sulphoxides. Separation of these metals from one another can be achieved by suitable choice of the extracted conditions. The nature of the extractable metal species has been elucidated. 相似文献
2.
Synthesis of chlorobis/β-diketonato/oxotechnetium/V/ and tris/β-diketonato/technetium/III/ complexes
K. Hashimoto Y. Yamada T. Omori K. Yoshihara 《Journal of Radioanalytical and Nuclear Chemistry》1989,135(3):187-197
Chlorobis/-diketonato/ oxotechnetium/V/ complexes [TcOCl/-dik/2, -diketone=acetylacetone, benzoylacetone and dibenzoylmethane] were newly synthesized using macroamount of99Tc. These complexes were further separated into geometrical isomers. Furthermore, an improvement of the yields for the syntheses of tris/-dike-tonato/technetium/III/ complexes [Tc/-dik/3, -diketone=acetylacetone, benzoylacetone and 2-thenoyltrifluoroacetone] was examined using Tc/III/-thiourea complexes as a starting material. 相似文献
3.
The crystal structure of trisodium monophosphate hemihydrate was determined. The space group is and a unit cell contains eight formula units. The unit cell dimensions of are a = 9.631(3), b = 5.416(2), c = 16.938(8) Å, β = 102.60(5)°. The final R value is 0.027 for a set of 1430 independent reflections. This atomic arrangement is mainly a three-dimensional network of distorted NaO6 octahedra. The hydrogen bonding scheme is given. 相似文献
4.
Summary Single reverse water-gas shift (RWGS) and dehydrogenation of propane with CO2(DH-CO2) reactions in the presence and absence of the CrOx/SiO2 catalyst have been studied between 673 and 873 K. It was found that the CrOx/SiO2 catalyst is active both in the dehydrogenation of propane and in the RWGS reactions. The obtained results suggest that the
dehydrogenation of propane to propene in the presence of CO2on CrOx/SiO2can be facilitated by the RWGS reaction.</o:p> 相似文献
5.
Summary CexTi1-xO2 and H3PW12O40/CexTi1-xO2 catalysts were prepared using a sol-gel method, and applied to the direct synthesis of dimethyl carbonate from methanol and
carbon dioxide. H3PW12O40/CexTi1-xO2 showed a better catalytic performance than the corresponding CexTi1-xO2, due to the bifunctional catalysis of Br?nsted acid sites (provided by H3PW12O40) and base sites (provided by CexTi1-xO2). H3PW12O40/Ce0.1Ti0.9O2 showed the highest catalytic performance among the H3PW12O40/CexTi1-xO2 catalysts. 相似文献
6.
Ninh Nguyen Jacques Choisnet Maryvonne Hervieu Bernard Raveau 《Journal of solid state chemistry》1981,39(1):120-127
Oxygen defect K2NiF4-type oxides have been synthesized for a wide composition range: 0 ≤ x ≤ 1.34. From the X-ray and electron diffraction study three domains have been characterized: orthorhombic compounds with La2CuO4 structure for 0 ≤ x < 0.10, tetragonal oxides similar to LaSrCuO4 for 0.10 ≤ x < 1 and several superstructures derived from the tetragonal cell ( with n = 3, 4, 4.5, 5, 6) for 1 ≤ x ≤ 1.34. The compounds corresponding to 0 < x < 1 differ from the other oxides in that they are characterized by the presence of copper with two oxidation states: + 2 and + 3. A model structure for La0.8Sr1.2CuλO3.4, in which copper has only the + 2 oxidation state, and for which the actual cell is tegragonal—a = 18.804 Å and c = 12.94 Å—has been established. The particular structural evolution of these compounds is discussed in terms of a competition between the capability of Cu(II) to be oxidized to Cu(III) and the ordering of oxygen vacancies. 相似文献
7.
Grisel Corro Odilón Vázquez-Cuchillo Fortino Ba?uelos 《Reaction Kinetics and Catalysis Letters》2005,87(1):171-175
Summary A strong promoting effect of the presence of C3H8or C3H6was determined for the combustion of CH4in excess oxygen, over pre-sulfated 1%Pt/g-Al2O3and pre-sulfated 1%Pt-2%Sn/g-Al2O3catalysts.</o:p> 相似文献
8.
P.P. Edwards R.G. Egdell I. Fragala J.B. Goodenough M.R. Harrison A.F. Orchard E.G. Scott 《Journal of solid state chemistry》1984,54(2):127-135
HeI-excited valence-band ultraviolet photoelectron spectra and MgKα-excited Ti-2p X-ray photoelectron spectra are reported for the spinel materials LiTi2O4 and . The presence of a Fermi edge in the ultraviolet photoelectron spectrum of LiTi2O4 confirms the metallic nature of this material, although the measured density of states at the Fermi energy is much lower than that expected from an independent-electron interpretation of the magnetic susceptibility. This difference is attributed to a strong interaction of the conduction electrons with the lattice vibrations. The localization of conduction electrons that occurs in the final state in the Ti-2p X-ray photoelectron spectrum of LiTi2O4 is attributed to a Coulomb interaction with a core hole. 相似文献
9.
A series of single-phase LixNi0.8-yCo0.2ZnyOp(0.96 ≤x≤ 1.10, 0 ≤y≤ 0.05, 2 ≤p≤ 2(1+y) ) (different in the y values) were synthesized by a two-step solid state reaction method, in which LiOH·H2O, Zn-doped spherical Ni(OH)2 and Co2O3 were used as the precursors. The ICP-AES analyses proved that the Zn-doped compounds synthesized had the nonstoichiometric form. The results of the XRD, SEM identified that the uniform particles of the as-prepared materials having a good layered structure were fine, narrowly distributed and well crystallized. The electrochemical performance test was carried out and the results showed that the as-prepared Zn-doped materials had not only a high capacity, but also a better cycling stability characterization than the un-doped one. The Li1.06Ni0.75Co0.22Zn0.03O2.03 material has an initial reversible capacity as high as 160.5mAh·g-1; and a first discharge efficiency 89.2%, and exhibits satisfactory cyclic stability with 90% retainable capacity after 50 cycles. 相似文献
10.
采用高温固相法制备了4种高纯度晶相组成的LixZryOz三元化合物,研究了焙烧温度、时间、反应物的种类和初始反应物物质的量比对产物组成的影响,进一步用XRD、SEM及BET分析方法对产物的晶相结构、表面形貌及比表面积进行了表征.实验结果表明,Li2CO3与ZrO2在适当条件下可以合成得到单斜相Li3ZrO3;以LiOH替代Li2CO3,在适当条件下可以分别合成得到四方相Li2ZrO3和三斜/单斜相Li6Zr2O7;进一步以Zr(NO3)4·5H2O代替Zr02,可将单斜相Li6Zr2O7的制备时间由96 h缩短至24 h.SEM照片显示产物硬团聚明显,粒径分布在1~10μm间,BET分析表明样品比表面积处于1.0~9.0 m2·g-1间分布,反应过程中锂的过量以及长时间高温焙烧是引起产物粒径长大和产生硬团聚的主要原因. 相似文献
11.
Mónica Martos Beatriz Julián Eloisa Cordoncillo 《Journal of solid state chemistry》2007,180(2):679-687
Doped-rutile has been traditionally used in ceramic pigments for its intense optical properties. In this paper, we compare the classical ceramic synthesis of Ti1−2xNbxNixO2−x/2 system with the sol-gel methodology, which allows a reduction of the anatase-rutile transformation temperature. The composition was optimised in order to obtain a unique rutile phase with the minimum amount of pollutant Ni(II) and enhanced chromatic coordinates. Incorporation of the doping ions in the rutile structure was corroborated by XRD and Rietveld refinements. The species responsible for the colour mechanism were studied by different techniques. UV-VIS spectroscopy showed the characteristic features of Ni2+ ions, whose existence was corroborated by EPR and magnetic measurements. From these results, (Ni,Nb)doped-TiO2 powder samples can be now shaped as thin films, monoliths, etc. by using sol-gel methodology without modifying their properties. This study introduces new possibilities of coloured TiO2-based solid solutions in new combined advanced applications (colouring agent and photocatalyst, etc.). 相似文献
12.
Nitrogen substituted yellow colored anatase TiO2−xNx and Fe-N co-doped Ti1−yFeyO2−xNx have been easily synthesized by novel hydrazine method. White anatase TiO2−δ and N/Fe-N-doped samples are semiconducting and the presence of ESR signals at g ∼1.994-2.0025 supports the oxygen vacancy and g∼4.3 indicates Fe3+ in the lattice. TiO2−xNx has higher conductivity than TiO2−x and Fe/Fe-N-doped anatase and the UV absorption edge of white TiO2−x extends in the visible region in N, Fe and Fe-N co-doped TiO2, which show, respectively, two band gaps at ∼3.25/2.63, ∼3.31/2.44 and 2.8/2.44 eV. An activation energy of ∼1.8 eV is observed in Arrhenius log resistivity vs. 1/T plots for all samples. All TiO2 and Fe-doped TiO2 show low 2-propanol photodegradation activity but have significant NO photodestruction capability, both in UV and visible regions, while standard Degussa P-25 is incapable in destroying NO in the visible region The mid-gap levels that these N and Fe-N-doped TiO2 consist may cause this discrepancy in their photocatalytic activities. 相似文献
13.
Uranyl fluoride, UO2F2, and a lithiated uranyl fluoride, Li2UO2F2, have been studied as the electrochemically active materials in nonaqueous lithium batteries. Both open circuit and discharge potentials have been measured as a function of utilization. The reversibility of the couple has been demonstrated. It is concluded that the phase Li2UO2F2 is an end member of a nonstoichiometric homogeneity range of generalized composition LixUO2F2 where x varies from 0 to 2. 相似文献
14.
15.
C. Lepoittevin S. Malo N. Barrier G. Van Tendeloo 《Journal of solid state chemistry》2008,181(10):2601-2609
Two-ordered perovskites, Bi1/3Sr2/3FeO2.67 and Bi1/2Ca1/2FeO2.75, have been stabilized and characterized by transmission electron microscopy, Mössbauer spectroscopy and X-ray powder diffraction techniques. They both exhibit orthorhombic superstructures, one with a≈b≈2ap and c≈3ap (S.G.: Pb2n or Pbmn) for the Sr-based compound and one with a≈b≈2ap and c≈8ap (S.G.: B222, Bmm2, B2mm or Bmmm) for the Ca-based one. The high-resolution transmission electron microscopy (HRTEM) images evidence the existence of one deficient [FeOx]∞ layer, suggesting that Bi1/3Sr2/3FeO2.67 and Bi1/2Ca1/2FeO2.75 behave differently compared to their Ln-based homolog. The HAADF-STEM images allow to propose a model of cation ordering on the A sites of the perovskite. The Mössbauer analyses confirm the trivalent state of iron and its complex environment with three types of coordination. Both compounds exhibit a high value of resistivity and the inverse molar susceptibility versus temperature curves evidence a magnetic transition at about 730 K for the Bi1/3Sr2/3FeO2.67 and a smooth reversible transition between 590 and 650 K for Bi1/2Ca1/2FeO2.75. 相似文献
16.
K. Ashok Rao B. V. Acharya N. Muralidhar B. Rangamannar 《Journal of Radioanalytical and Nuclear Chemistry》1985,94(6):351-355
A method for the separation of Tl/III/from Tl/I/ is reported employing 1-/2-pyridylazo/-2-naphthol /PAN/ and Rhodamine-B as extracting agents. 相似文献
17.
Reaction of BaO, Nb2O5, and Nb in mole ratios of 2.4:1.6:1 in an evacuated silica capsule at 1250°C produces a mixture of at least two products, one of which has the probable composition . This compound has an hexagonal unit cell of dimensions a = 9,034 ± 0.004 Å, c = 27.81 ± 0.02 Å, probable space group . Its structure has been determined from 942 independent reflections collected by a counter technique and refined by least squares methods to a conventional R value of 0.062. The basic structure consists of strings of four NbO6 octahedra sharing opposite corners, each string joined to the next by edge sharing of the end octahedra, so that the c axis corresponds to the length of a strand of seven corner-linked octahedra. Chains of three such strands are formed by corner sharing between the strands. The chains in turn are joined by NbO6 octahedra and Si2O7 groups in which the SiOSi linkage is linear. Barium atoms are in sites between the chains coordinated by 13 oxygen atoms. A second site, 15 coordinated, probably has a small amount of barium as well; the fractional occupancy for barium in this site is 0.076. 相似文献
18.
Hans-Peter Abicht Peter Lehniger Kurt Issleib 《Journal of organometallic chemistry》1983,250(1):609-616
The complexes of type R2)2 (M = Pd, Pt) are readily deprotonated by n-Buli under various conditions yielding μ-C-bis-dilithiated species. The resulting carbanions are attacked by the electrophiles Mel, Me3SiCl and Ph2PCl to form the corresponding disubstituted derivatives. The reaction with AuCl . PPh3 yields heterobimetallic complexes with two different MC σ-bonds. The compounds obtained are analytically and spectroscopically characterized. 相似文献
19.
Samer Aouad Amal Aoun Mira Skaf Madonna Labaki John El Nakat Bilal El Khoury Pierre Obeid Edmond Abi-Aad Antoine Aboukaïs 《Comptes Rendus Chimie》2013,16(10):868-871
The effects of CoxMgyAl2Oz mixed oxides composition and ruthenium addition on the oxidation of propylene and carbon black (CB) were investigated. Different reactive cobalt and ruthenium oxide species were formed following calcination at 600 °C. The addition of ruthenium was beneficial for the CB oxidation under “loose contact” conditions and for propylene oxidation when the cobalt content was intermediate to low. The calculated activation energy for CB oxidation was decreased from 151 kJ mol−1 for the uncatalyzed reaction to 111 kJ mol−1 over the best catalyst. 相似文献
20.
Najmeddine Abdelmoula Hamadi Khemakhem Mario Maglione 《Journal of solid state chemistry》2006,179(12):4011-4019
The perovskite-type oxides Ba1−xLax(1−y)/2Euxy/2Nax/2TiO3 (0?x?0.5 and xy=0.04) were synthesized and characterized by X-ray diffraction as well as dielectric measurements and Raman spectroscopy. The crystal structure of these ceramics has been determined by the Rietveld refinement powder X-ray diffraction data at room temperature. These compounds crystallize at room temperature in tetragonal space group P4mm for 0?x?0.1 and in the cubic group for 0.2?x?0.5. The phase transition temperature TC (or Tm) decreases as x content increases. The degree of diffuseness of the phase transition is more pronounced for higher x content, implying the existence of a composition-induced diffuse phase transition of the ceramics with x?0.1. The evolution of the Raman spectra was studied as a function of various compositions at room temperature. The polarization state was checked by pyroelectric measurements. 相似文献