The segregation of As,Sb and Bi in Cr-Ni steels and alloys with different Ni contents investigated using AES

This paper reports on an AES study of grain boundary segregation in five kinds of Cr-Ni corrosion-resistant steels and alloys with different Ni contents that were enriched by As, Sb or Bi. The results show that all mentioned impurities segregate to the grain boundaries and that the segregation level depends on the type of the impurity. The highest amount of segregant atoms was found in the case of Bi, while it appeared to be substantially lower for As and Sb. The segregation level of each impurity grows also with the Ni content. This increase is more pronounced for Bi and Sb than for As. In particular the results demonstrate that the enrichment of grain boundaries by a given impurity is strongly connected to the solubility of this element in the matrix.Dedicated to Professor Günther Tölg on the occasion of his 60th birthday     

Processing and characterization of new passive and active oxysulfide glasses in the Ge-Ga-Sb-S-O system

New passive and active oxysulfide glasses have been prepared in the Ge-Ga-Sb-S-O system employing a two-step melting process which involves the processing of the chalcogenide glass (ChG) and its subsequent melting with amorphous GeO₂ or Sb₂O₃ powder. Optical characterization of the oxysulfide glasses has shown that the UV cut-off wavelength decreases with increasing oxygen content. Using Raman spectroscopy, correlations have been made between the formation of new Ge- and Sb-based oxysulfide structural units, the Sb content and the O/S ratio. We demonstrate the successful processing of active rare earth doped oxysulfide glasses by melting the chalcogenide glass with Er₂O₃ and Sb₂O₃ and also by melting the Er³⁺ doped chalcogenide glass with Sb₂O₃. Modification of the emission spectra at 1500 nm of Er³⁺ doped samples with the introduction of oxygen revealed that Er³⁺ most likely exists in dual O- and S-neighbor environments. Finally, the photo-response of these new glasses upon near-IR femtosecond laser irradiation has been investigated as a function of Sb content and O/S ratio and shows that the glasses are photo-sensitive to NIR fs laser light with the magnitude of the photo-sensitivity dependent on the glass’ Sb content and O/S ratio.     

纳米晶(CeO2)1-x(BiO1.5)x固溶体的水热合成与离子输运性质研究

在240℃水热体系中首次合成出系列纳米晶固溶体(CeO₂)_1-x(BiO_1.5)_x(x=0.0～0.50).产物采用X射线衍射,扫描电子显微镜和X射线光电子能谱仪进行表征.Bi₂O₃在CeO₂中的固溶限约为50%.所有固溶体结晶属立方萤石结构,粒度范围为10～18nm.当Bi₂O₃掺杂量小于固溶限时,于800℃烧结不会导致结构转变.而对于(CeO₂)_0.5(BiO_1.5)_0.5,于800℃在空气中烧结将导致固溶限降低.Bi₂O₃含量低于固溶限时,固溶体只具有体电导,而(CeO₂)_0.6(BiO_1.5)_0.4的总电导可分为体电导和晶界电导.体电导为氧离子,而晶界为来自电极的银离子.     

Recent advances in characterization of CaCu3Ti4O12 thin films by spectroscopic ellipsometric metrology

CaCu3Ti4O12 (CCTO) thin films were successfully grown on LaAlO3(100) and Pt/TiO2/SiO2/Si(100) substrates by a novel MOCVD approach. Epitaxial CCTO(001) thin films have been obtained on LaAlO3(100) substrates, while polycrystalline CCTO films have been grown on Pt/TiO2/SiO2/Si(100) substrates. Surface morphology and grain size of the different nanostructured deposited films were examined by AFM, and spectroscopic ellipsometry has been used to investigate the electronic part of the dielectric constant (epsilon2). Looking at the epsilon2 curves, it can be seen that by increasing the film structural order, a greater dielectric response has been obtained. The measured dielectric properties accounted for the ratio between grain volumes and grain boundary areas, which is very different in the different structured films.     

Thermal conductivity and interfacial energy of solid Bi solution in the Bi–Al–Zn eutectic system

The equilibrated grain boundary groove shapes for solid Bi solution (Bi–6.1 at.%Zn–0.38 at.%Al) in equilibrium with the Bi–Al–Zn eutectic liquid have been observed from quenched sample with a radial heat flow apparatus. The Gibbs–Thomson coefficient, solid–liquid interfacial energy and grain boundary energy of solid Bi solution have been determined from the observed grain boundary groove shapes. The variations of thermal conductivity with temperature for solid Bi solution (Bi–6.1 at.%Zn–0.38 at.%Al) has been measured up to five degree below the melting temperature by using radial heat flow technique. The ratio of thermal conductivity of equilibrated Bi–Al–Zn eutectic liquid phase to solid Bi solution (Bi–6.1 at.%Zn–0.38 at.%Al) phase has also been measured with a Bridgman type growth apparatus at the melting temperature.     

Analysis of Antimony Doping in Tin Oxide Thin Films Obtained by the Sol-Gel Method

The antimony doping in SnO₂ thin films prepared by the sol-gel dip-coating method has been studied using two characterization techniques. In order to determine the actual doping level directly in the deposited layers, X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS) have been used. We found that this doping level is systematically lower than expected from the starting solutions composition, and that two oxidation states are present: Sb³⁺ and Sb⁵⁺. As the antimony content increases, there is a competition between Sb⁵⁺ and Sb³⁺ species.The SnO₂: Sb thin films have also been observed by transmission electron microscopy (TEM), showing that the measured mean size of crystallites decreases as the Sb content increases in the oxide. No precipitates of either Sn or Sb oxides (other than SnO₂) could be detected.     

Electrochemical study of the Sb(V)/Sb(III) couple on a glassy carbon rotating-disk electrode

The kinetics of the reduction of Sb(V) at a glassy carbon rotating-disk electrode have been investigated in 9.5 M HCl. The current-potential curve is characterized by a single irreversible wave, the limiting current being linearly related to the Sb(V) concentration and the square root of the rotation rate. Kinetic parameters of the reaction have been evaluated. Anodic oxidation currents of Sb(III) cannot be quantitatively measured owing to the interference of the oxidation of chloride.     

Solid-liquid interfacial energy of neopentylglycol

The grain boundary groove shapes for equilibrated solid neopentylglycol (2,2-dimethyl-1,3-propanediol) (NPG) with its melt were directly observed by using a horizontal temperature gradient stage. From the observed grain boundary groove shapes, the Gibbs-Thomson coefficient (Gamma), solid-liquid interfacial energy (sigma(SL)), and grain boundary energy (sigma(gb)) of NPG have been determined to be (7.4+/-0.7)x10(-8) Km, (7.9+/-1.2)x10(-3) Jm(-2), and (15.4+/-2.5)x10(-3) Jm(-2), respectively. The ratio of thermal conductivity of equilibrated liquid phase to solid phase for the NPG has also been measured to be 1.07 at the melting temperature.     

Determination of trace elements in food by neutron activation analysis

Neutron activation analysis (NAA) methods have been developed for the determination of major, minor and trace elements in duplicate diets and individual food items. These include a cyclic instrumental NAA (CINAA) method for measuring Se content through its short-lived nuclide^77mSe; epithermal INAA (EINAA) for I and As; conventional INAA for Br, Ca, Cl, Co, Cr, Fe, K, Mg, Mn, Na, Rb, Sb, Sc, Sn and Zn; combination of EINAA and INAA for Al; radiochemical NAA (RNAA) for As, Au, Co, Cu, Fe, Hg, Mo, Sb, Se and Zn; and preconcentration NAA (PNAA) for U and Th. Accuracy of measurements have been evaluated by analyzing a number of biological and diet reference materials. Multielement concentrations of diets and foods have been measured by these methods.     

Nonstoichiometry in B8-Type NiSb

The phase diagram of the nickel-antimony system has been investigated between 40 and 54 at% Sb. The congruent melting point of γ-NiSb (with NiAs-structure) was found at 47 at% Sb and 1432 ± 5 K. Lattice parameters and pycnometric density of this phase were determined as a function of composition; both exhibit a change of slope between 50 and 51 at% Sb rather than exactly at the stoichiometric composition. In the same concentration range a flat minimum was also found in the composition dependence of the magnetic susceptibility measured at room temperature. These effects are explained by the following defect mechanism: Starting at the antimonyrich phase boundary nickel atoms will at first occupy octahedral sites. However, before these sites are completely filled, nickel atoms will start to fill the trigonal-bipyramidal holes (interstitial sites) of the NiAs-lattice.     

Grain Boundary Wetting in Polycrystals: 1. Probability of Wetting of Structural Elements

A model describing the wetting of structural elements in polycrystals such as grain boundaries (faces), triple lines (edges), and quaternary nodes (vertices) is proposed. It is assumed that the only driving force during wetting is the tendency of a system to the energy minimization due to the substitution of low-energy liquid–solid interfaces for high-energy grain boundaries. In this case, the anisotropy of grain boundary energy caused by the differences in misorientation of adjacent grains is taken into account, whereas the liquid–solid interface energy is assumed to be independent of the orientation. The well-known condition of grain boundary wetting (the Gibbs–Smith condition) is extended to the triple lines and quaternary nodes by introducing parameters determined as characteristic free energy of these elements.     

Preparation of a118Te/118Sb radionuclide generator

The development of a new radionuclide generator, based on¹¹⁸Te/¹¹⁸Sb, has been studied. The 3.5 minute¹¹⁸Sb daughter activity decays principally by positron emission and has potential use as a flow tracer. The¹¹⁸Te parent is conveniently produced by proton bombardment of antimony targets. A simple and efficient scheme for the separation of radiotellurium from proton-irradiated antimony targets has been developed, and thin-target cross sections for¹²¹Sb(p, 4n)¹¹⁸Te and competing reactions have been determined. For antimony targets irradiated with 46 MeV protons, the yields (mCi/g Ah) of¹¹⁸Te,^119mTe and¹¹⁹Te were measured to be 0.71, 0.33 and 1.9, respectively. The adsorption and elution characteristics of activated carbon for tellurium have been evaluated for use as a column chromatography adsorbent in a¹¹⁸Te/¹¹⁸Sb generator. The conditions for optimal¹¹⁸Sb elution and minimal¹¹⁸Te breakthrough for promising systems are presented.     

Sol-Gel Derived Titania/γ-Glycidoxypropyltrimethoxysilane and Methyltrimethoxysilane Hybrid Materials for Optical Waveguides

We report here on titania/organically modified silane hybrid materials produced by the sol-gel technique for optical waveguide applications. Acid catalyzed solutions of -glycidoxypropyltrimethoxysilane and methyltrimethoxysilane mixed with tetrapropylorthotitanate have been used as precursors for the hybrid materials. Waveguide films with a thickness about 1.3-m have been prepared on a silicon substrate by a single-coating process and low-temperature heat treatment. Atomic force microscopy (AFM), thermal gravimetric analysis (TGA), UV-visible spectroscopy (UV-VIS), and Fourier transform infrared (FTIR) spectroscopy have been used to investigate the optical and structural properties of these waveguide films. The results have shown that dense, pore-free, and highly transparent films can be obtained by low temperature heat treatment. The planar waveguide propagation loss of the hybrid films has also been measured.     

Solvent Dependence of the Hydrolysis Products of Mn2Sb4(OEt)16

The hydrolysis-condensation pathways of Mn2Sb4(OEt)16 in various ethanol-toluene solvents have been studied for h < 1.5 (h = H2O/Mn2Sb4(OEt)16). The hydrolysis was performed by slow addition of H2O diluted with the ethanol-toluene solvent. Mn2Sb4(OEt)16 and its hydrolysis products were studied by FT-IR spectroscopy, SEM-EDS and single-crystal X-ray diffraction. The hydrolysis pathway for a given h-value was found to depend on the solvent composition. In ethanol-rich solvent mixtures, Mn7Sb4O4(OEt)18(HOEt)2 was obtained in maximum yield at h = 1.14, and in toluene-rich solvents, Mn8Sb4O4(OEt)20 was obtained in maximum yield at h = 1.0. In both cases, the remaining Sb was found as nonhydrolyzed Sb(OEt)3. The structures of the heterometallic ethoxides Mn2Sb4(OEt)16, Mn7Sb4O4(OEt)18(HOEt)2 and Mn8Sb4O4(OEt)20 have been determined earlier by single-crystal X-ray diffraction. According to FT-IR evidence the molecular structures of the latter two are retained almost intact in solution, whereas the first one changes appreciably. The hydrolysis products of Mn2Sb4(OEt)16 are compared with those of Ni2Sb4(OEt)16, and the structural and compositional changes in different solvents and at different h-values are discussed.     

Differential scanning calorimetry of semiconducting As-Se glasses containing Sb

The compositional dependence of the glass transition temperature (T _g), and the temperature of the maximum rate of crystallization (T _p) of As-Se glasses containing Sb has been measured using non-isothermal DSC. The variation of these characteristic temperatures is found useful in interpreting the structural changes in As-Sb-Se glasses. The role of Sb in these glasses and its effect on the crystallization characteristics is analyzed.     

Synthesis, structure and magnetic properties of A2MnB′O6 (A=Ca, Sr; B′=Sb, Ta) double perovskites

A₂MnB′O₆ (A=Ca, Sr; B=Sb, Ta) double perovskites have been synthesized and their structural and magnetic properties have been investigated. Rietveld refinement of the powder X-ray diffraction data for Sr₂MnSbO₆ indicated significant ordering of Mn and Sb at the B-site while all other phases showed mostly a random distribution of the B-site cations. X-ray absorption spectroscopic data established the presence of Mn in the 3+ and Sb/Ta in the 5+ oxidation states in all the phases. Magnetic susceptibility data indicated ferromagnetic correlations for all the A₂MnB′O₆ phases with Weiss temperatures varying from 64 to 107 K.     

Dielectric and impedance properties of Sr(Sm0.5Nb0.5)O3 ceramics

Perovskite types Sr(Sm_0.5Nb_0.5)O₃, (SSN) ceramics have been prepared through solid state reaction route. The scanning electron microscopy provides information on the quality of the samples and uniform grain distribution over the surface of the samples. The field dependence of the dielectric response was measured in a frequency range from 50 Hz to 1 MHz and in a temperature range from 60 °C to 420 °C indicates polydispersive nature of the materials. An analysis of the dielectric constant (?′) and tangent loss (tanδ) with frequency is performed assuming a distribution of relaxation times as confirmed by the scaling behavior of electric modulus spectra. The frequency dependence of the electric modulus peak is found to obey Arrhenius law with activation energy of ∼0.026 eV. The complex plane impedance plot shows the grain boundary contribution for higher value of dielectric constant in the law frequency region. The frequency dependence of electrical data is also analyzed in the framework of conductivity and electric modulus formalisms. Both these formalisms show qualitative similarities in relaxation times. The scaling behavior of imaginary part of electric modulus M″ suggests that the relaxation describes the same mechanism at various temperatures in SSN.     

稀土对高强锌合金耐磨性和耐蚀性的影响

ＺＡ２７合金中加入稀土，由于合金化，变质等作用使合金微观组织发生变化，强化了合金，因此提高了合金的综合性能和耐磨性，又因稀土加入能净化晶界，对电化学性产生有利影响，所以合金的耐蚀性也得到改善。     

Investigating the antimony determination in environmental samples by NAA

In recent years, environmental concerns regarding antimony have grown considerably due to anthropogenic processes that have resulted in increasing concentration of Sb in the environment, and also because of its impacts and possible adverse effects to living organisms. Several techniques have been used, to obtain reliable results for Sb, since Sb is present at low level concentration, requiring analytical instrumentation with low detection limits. The neutron activation analysis (NAA) technique has a high metrological level for the determination of several elements in different matrices. However, Sb determination in environmental and biological samples presents some analytical difficulties due to its low concentrations and gamma ray spectrum interferences. The objective of this research was to study on Sb determination in environmental reference materials by NAA. Ten environmental reference materials were selected and analyzed using long period irradiation at IEA-R1 research nuclear reactor. The induced gamma activities of ¹²²Sb and ¹²⁴Sb were measured. Relative errors of the results demonstrated that the accuracy depends mainly on Sb radioisotope measured, the decay time for counting and the sample composition.     

AES study of underclad cracking

The present work deals with the occurrence of underclad cracks in three types of steels differing in the contents of the alloying elements (Cr, Ni, Mn) and in the impurities level (As, Sb, Sn). The presence of the intercrystalline fracture typical for the underclad cracks was proved to be dependent on the temperature and on the ageing time. It follows from the results of Auger electron spectroscopy, that the sulphur and phosphorus segregations accompanied by a higher number of carbide (possibly sulphide) particles cause a decrease of grain boundary strength. Segregations of other impurity elements were not detected at grain boundaries.