Compositions of phases in the interaction of rare-earth metals with selenium

The interaction of rare-earth metals (Pr, Nd, Sm, Y, Er, and Yb) with selenium at Ln: Se = 1: 2, 2: 3, 3: 4, and 1: 1 under polythermal (293–1270 K) and isothermal (770 and 1170 K) heat treatment conditions was studied by differential thermal and X-ray powder diffraction analyses. While heating the reaction mixture, the exothermic events in the interaction between elements occur within the temperature ranges 620–750 K (Pr), 580–870 K (Sm), and 620–920 K (Er). X-ray powder diffraction analysis detected the formation of the following phases in the homogeneous state: at 770 K, LnSe₂ and Yb₂Se₃, and at 1170 K, Ln₃Se₄, Ln₂Se₃, and YbSe. Scanning electron microscopy showed that particles of the selenide phases are formed by 1 × 2–5-μm fragments, which constitute a spongy structure of agglomerates tens to hundreds of micrometers in size.     

Synthesis and characterization of water-soluble CdSe nanoparticles capped by AOT

Water-soluble CdSe nanoparticles were synthesized using AOT (sodium bis(2-ethylehexyl)-sulfosuccinate) as stabilizer, cadmium acetate and Na2SeSO3 as precursors in aqueous phase. The influence of some key factors, such as reaction time, temperature, concentration and molar ratio of precursors on the optical properties of CdSe nanoparticles was systematically investigated through UV-Vis and PL spectra. Powder X-ray diffraction (XRD) was used to characterize the crystalline structure of synthesized CdSe nanoparticles. As-prepared CdSe nanoparticles exhibit an apparent quantum confinement effect and typical hexagonal wurtzite structures. Finally, the optimal experimental conditions were obtained.     

Ionic liquid of [Bmim]Cl for the preparation of hierarchical nanostructured rutile titania

The rutile titania with hierarchical nanostructure was conveniently prepared in a room temperature ionic liquid (RTIL) of [Bmim]⁺Cl⁻ system. The obtained materials were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N₂ adsorption-desorption analysis. XRD patterns revealed that only rutile phase was formed in the ionic liquid of [Bmim]⁺Cl⁻. The SEM and TEM micrographs as well as N₂ adsorption-desorption measurements showed that the nanorods of rutile titania were interaggregated to fabricate a large mesoporous structure and the voids packed in the nanorods formed a small mesostructure. It was proposed that the formation of rutile crystal phase was due to high acidity and high Cl⁻ content in the special reaction media, and also the combination of ionic liquid-templated effects with so-called reaction limited aggregation resulted in the hierarchical nanostructure.     

片状MoS2/MoS1.5Se0.5纳米复合材料的制备及其摩擦学性能研究

将钼粉与升华硫和硒粉的混合粉末按一定化学计量比混合,通过固相反应法成功制备出了均匀的片状纳米颗粒。分别使用X射线粉末衍射仪(XRD)、扫描电子显微镜(SEM)以及透射电子显微镜(TEM)对该纳米粉体进行结构表征和分析,发现该粉体为MoS2/MoS1.5Se0.5混合晶相,晶粒尺寸在300~600 nm,厚度约为5 nm的片状结构。将该MoS2/MoS1.5Se0.5纳米片作为润滑油添加剂添加到基础油中,使用UMT-2型摩擦磨损试验机对其摩擦学性能进行测试,并对摩擦机理进行了解释,结果表明MoS2/MoS1.5Se0.5纳米片作为润滑油添加剂具有良好的减摩抗磨性能。     

Powder X-ray diffraction study of the double complexes [M(NH3)5Cl][M"Cl4] as precursors of metal powders (M = Ir,Rh, Co; M" = Pt,Pd)

According to the results of powder X-ray diffraction study of the complex salts of composition [M(NH₃)₅Cl][M"Cl₄] (M = Ir, Rh, or Co and M" = Pt or Pd), the anhydrous salts crystallize in the orthorhombic system (space group Pnma) and are isostructural to the [Ir(NH₃)₅Cl][PtCl₄] complex studied previously. The unit cell parameters of the resulting salts were refined. The metal powders, which were obtained by thermal decomposition of these salts under an atmosphere of hydrogen, were studied by powder X-ray analysis.     

Neue ternäre Selenide der Lanthanide durch Reduktion der Sesquiselenide

New Ternary Selenides of Lanthanoides by Reduction of Sesquiselenides The compounds MLn₂Se₃ (M = Na; Ln = La? Sm) and MLn₈Se₁₂ (M = Na, Ca; Ln = La? Sm) were prepared by reduction of the corresponding lanthanide sesquiselenides with sodium and calcium, respectively, for the first time. Further-more MLa₈Se₁₂ (M = Sr, Eu) could be obtained in an analogous way. All compounds were characterized by chemical analysis and X-ray powder diffraction. The electronic structures of these compounds were investigated by band structure calculations and magnetic measurements.     

Kristallstruktur der Tieftemperaturmodifikation von RuTe2

Crystal Structure of the Low Temperature Modification of RuTe₂ Black shining, platelet like single crystals of α-RuTe₂ were obtained by chemical transport reaction with Cl₂/AlCl₃ (crystal dimensions up to 1 mm). The crystal structure of this low temperature modification of α-RuTe₂ hitherto only known from powder measurements, was redetermined at room temperature by single crystal X-ray diffraction on a four-circle diffractometer. α-RuTe₂ crystallizes in the marcasit structure typ in the orthorhombic spacegroup Pnnm (No. 58) with the lattice constants a = 528.12(13), b = 639.43(19), c = 400.85(13) pm.     

Osmium thioselenochloride Os<Subscript>2</Subscript>S<Subscript>6</Subscript>Se<Subscript>2</Subscript>Cl<Subscript>8</Subscript>: Synthesis,cluster isolation,and structure

The quaternary thioselenochloride complex Os₂S₆Se₂Cl₈ (I) was obtained by a reaction of OsO₄ with a solution of Se in S₂Cl₂ at 100°C and identified by combination of X-ray diffraction (polycrystalline approach) and cluster framework isolation. A reaction of complex I with melted 4-cyanopyridine (4-CNPy) at 165°C gave the complex Os₂S₂Cl₄(4-CNPy)₄, which confirms the integrity of the binuclear cluster frame-work [Cl₂OsS₂OsCl₂] in complex I.     

Synthesis and characterization of monodisperse CdSe quantum dots in different organic solvents

Nearly monodisperse CdSe quantum dots (QDs) have been prepared by a soft solution approach using air-stable reagents in different organic solvents. This scheme is a supplement to the conventional thermal decomposition of organometallic compounds at higher temperatures. CdSe nanocrystals of different sizes could be obtained by simply changing the solvent. This method is reproducible and simple and thus can be readily scaled up for industrial production. The reaction process was monitored by the temporal evolution of the UV-Vis absorption and room temperature photoluminensce spectra. The structures of the CdSe quantum dots were determined by X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). The phase-transfer of oleic acid-stabilized CdSe nanocrystals into PBS buffer solutions was also studied for their potentials in biological applications. __________ Translated from Journal of Shanghai Jiaotong University, 2005, 39(1) (in Chinese)     

Syntheses and characterization nano-structured bismuth(III) oxide from a new nano-sized bismuth(III) supramolecular compound

Nano-particles of a new Bi(III) supramolecular compound, {Bi₂(μ-4,4′-bipy)Cl₁₀] · 2(4,4′-Hbipy) · (4,4′-H₂bipy) · 2H₂O} (1) {4,4′-bipy = 4,4′-bipyridine}, were synthesized by a sonochemical method. The nano-material was characterized by scanning electron microscopy, X-ray powder diffraction (XRD), IR spectroscopy and elemental analyses. Crystal structure of compound 1 was determined by X-ray crystallography. Calcination of the nano-particles of compound 1 at 400 °C under air atmospheres yields nano-sized particles of α-Bi₂O₃.     

Magnetic properties of new complexes of 3d metal chlorides with 3-amino-4-ethoxycarbonylpyrazole

New complexes of Co(II), Ni(II), and Cu(II) chlorides with 3-amino-4-ethoxycarbonylpyrazole (L) of the composition ML₂Cl₂ are synthesized. The compounds are studied by powder X-ray diffraction, electronic and IR spectroscopy, static magnetic susceptibility (temperature range 2–300 K). It is found that in the ML₂Cl₂ complexes (M = Co(II), Ni(II), Cu(II)) ferromagnetic exchange interactions between the unpaired electrons of metal ions occur. In [CoL₂Cl₂] and [NiL₂Cl₂] compounds a transition to the magnetically ordered state (T _c ? 10–12 K) is observed.     

Phase equilibrium in the Sb2Se3-Gd2Te3 system

The Sb₂Se₃-Gd₂Te₃ system was studied using differential thermal analysis, X-ray powder diffraction, and microstructure examination. This is a quasi-binary system. Sb₂Se₃-based solubility at 300 K is 10 mol % Gd₂Te₃. The eutectic contains 20 mol % Gd₂Te₃ and melts at 760 K. One incongruently melting compound (870 K) of composition GdSbTe_1.5Se_1.5 was found in the system.     

Thermal analysis of cobalt,nickel and copper complexes of 2-aminothiazole

The thermal decomposition of 2-aminothiazole (2-amt) complexes of general formula M(2-amt)₂X₂ [M = Co(II) and Cu(II)] and Ni(2-amt)₄X₂ [X = Cl and Br] have been studied in air and argon by TG and DTG as well as by DTA in nitrogen; end products from the decompositions in air have been characterised by X-ray powder diffraction. Decomposition stoichiometries have been proposed and factors governing the thermal decomposition have been discussed.     

Aspects of ZnSe electrosynthesis from selenite and selenosulfite aqueous solutions

Cathodic electrodeposition of ZnSe is studied in aqueous acidic selenite (Se^(IV)O₂) baths of free Zn²⁺ ions and alkaline selenosulfite (Se⁰SO₃^2–) baths of zinc complex ions. The synthesis of polycrystalline, cubic ZnSe by Se^(IV)-diffusion-controlled electrodeposition from acidic solutions is optimized in terms of selenite concentration, while the effect of Ti, Ni, anodized Ti and CdSe substrates on the obtained layers growth and structural properties is investigated. Furthermore, the production of stoichiometric though amorphous ZnSe is demonstrated using selenosulfite solutions. The results are valuated by means of X-ray diffraction, scanning electron microscopy and reflectance spectroscopy techniques.     

Detection and Characterization of Compounds in the Mn‐W‐Cl System through a Combined Thermal Scanning ‐ XRD Approach

A procedure combining thermal analyses and XRD powder diffraction is used to scan and detect a series of new compounds in the Mn‐W‐Cl system. Four new ternary Mn‐W‐Cl compounds are formed in a progressive reaction of tungsten hexachloride (WCl₆) with manganese powder, in which tungsten is gradually reduced from W⁶⁺ to W²⁺. Among several DSC signals, the new compounds Mn_xWCl₆, MnW₂Cl₁₀, (Mn, W)_1–xCl₂, and MnW₆Cl₁₄ are detected and their crystal structures are assigned or identified by X‐ray diffraction techniques. Magnetic properties are reported for MnW₂Cl₁₀ and MnW₆Cl₁₄.     

An amperometric biosensor using toluidine blue as an electron transfer mediator intercalated in α-zirconium phosphate-modified horseradish peroxidase immobilization matrix

A novel H₂O₂ biosensor was constructed employing α-zirconium phosphate as a new support substrate to hold an electron shuttle toluidine blue between a glassy carbon electrode and horseradish peroxidase. Toluidine blue was intercalated into α-zirconium phosphate-modified horseradish peroxidase immobilization matrix cross-linked on a glassy carbon electrode surface via bovine serum albumin-glutaraldehyde. This co-immobilization matrix of the mediator and the enzyme was formed from the α-zirconium phosphate (α-ZrP)-toluidine blue (TB) inclusion colloid in which horseradish peroxidase (HRP) was dissolved. Intercalation of TB in layered α-ZrP was investigated by scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and electrochemical measurements. TB immobilized in this way underwent a quasi-reversible electrochemical redox reaction at the electrode. Cyclic voltammetry and amperometric measurements demonstrated good stability and efficiently-shuttled electrons between HRP and the electrode. The sensor responded rapidly to H₂O₂ with a detection limit of 3.0 × 10^–7 mol/L.     

Interaction in the TlSe-Pr2Se3 system

The interaction of components in the TlSe-Pr₂Se₃ system was studied by differential thermal, X-ray powder diffraction, and microstructural analyses and also by microhardness and density measurements. The state diagram of this system was constructed. It was found that the section TlSe-Pr₂Se₃ is a quasi-binary section of the Tl-Pr-Se ternary system. In the TlSe-Pr₂Se₃ system at the component ratio 1: 1, a new chemical compound, TlPr₂Se₄, forms, which melts congruently at 1295°C. In the system based on TlSe, solid solutions form until 3.5 mol % Pr₂Se₃, and in the system based on Pr₂Se₃, solid solutions occur until 2.5 mol % TlSe.     

Novel synthesis of a highly active carbon-supported Ru85Se15 chalcogenide catalyst for the oxygen reduction reaction

A carbon-supported Ru₈₅Se₁₅ chalcogenide catalyst was synthesized via a microwave-assisted polyol process using RuCl₃ and Na₂SeO₃ as the Ru and Se precursors. The Ru₈₅Se₁₅ chalcogenide catalyst was characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and inductively-coupled plasma-atomic emission spectroscopy (ICP-AES). The XRD pattern for Ru₈₅Se₁₅/C clearly exhibited the characteristic reflections of metallic ruthenium. The TEM image indicated that the Ru₈₅Se₁₅ chalcogenide catalyst was well dispersed on the surface of the carbon support with a narrow particle size distribution. Rotating disk electrode (RDE) and single-cell measurements were carried out to evaluate the electrocatalytic activity of the Ru₈₅Se₁₅ chalcogenide catalyst. The oxygen reduction reaction (ORR) activity of the Ru₈₅Se₁₅/C catalyst was compared with the commercial Pt/C catalyst with the absence/presence of methanol. In the absence of methanol, the Ru₈₅Se₁₅/C catalyst showed a comparable ORR activity with the Pt/C catalyst. However, in the presence of methanol, the Ru₈₅Se₁₅/C catalyst showed a better ORR activity than the Pt/C catalyst. The performance of the membrane electrode assembly (MEA) prepared with Ru₈₅Se₁₅/C as the cathode catalyst in a single proton exchange membrane fuel cell (PEMFC) showed the maximum power density of 400 mW cm⁻² at the current density of 1300 mA cm⁻².     

Gas-phase chlorine-initiated photooxidation of methanol and isopropanol

The photolysis of CH₃OH/Cl₂/air, CH₃OH/Cl₂/NO₂/air, and (CH₃)₂CHOH/Cl₂/NO₂/air at 28 ± 2°C was studied using the long-path FTIR method. The primary reactions of methanol and isopropanol with Cl atoms were α-hydrogen abstraction (100%), and α hydrogen (85%), and α-hydrogen abstraction (15%), respectively. The failure to detect hydroxyalkyl-peroxy nitrates suggested that the oxygen addition to α-hydroxy radicals is not important. From the product distribution an upper limit of the ratio of oxygen addition to CH₂OH and CH₃CHOH was estimated to be about 6 and 7%, respectively. The oxygen addition ratio to (CH₃)₂COH was very low. The reaction mechanism is also discussed.     

Carbochlorination of samarium sesquioxide

The chlorination of Sm₂O₃ in the presence of carbon using the gaseous mixture Cl₂(g)+Ar(g) has been studied by thermogravimetry. The effects of both the temperature between 200 and 950 °C and the total gas flow rate between 2.1 and 7.9 l h⁻¹ on the reaction rate were analyzed. The starting temperature of reaction, the stoichiometry and kinetic regimes of the reaction were obtained. Reactants and products were analyzed by X-ray diffraction (XRD) and electronic dispersive spectroscopy (EDS). The temporal evolution of the solid microstructure was followed by scanning electron microscopy (SEM).