新型Raney-Ni制备过程中的XRD,SEM和EDAX研究

采用急冷法及预处理制备Raney-Ni原始合金,以XRD,SEM和EDAX手段研究了其活化过程.此方法制备的Raney-Ni原始合金与传统方法制备的相比,晶粒变小,Ni₂Al₃相增多,从而使其具有中心为大量Ni₂Al₃,外围为少量NiAl3包裹的独特结构,使活化始终以铝向表面迁移为控制步骤,活化后残留较多的Ni₂Al₃相,催化剂中活性Ni均匀分布在残留的Ni₂Al₃上.     

Response mechanism of a neutral carrier Hg(II) polymeric membrane ion-selective electrode. SEM and EDAX study

Scanning electron microscopy (SEM) and energy dispersive atomic X-ray spectrometry (EDAX) were used to study the response mechanism of a previously reported new Hg membrane ion-selective electrode (ISE) based on 1,3-diphenylthiourea. These techniques allowed the study of the membrane surface characteristics, such as the morphological homogeneity and chemical composition. A 'twice Nernstian' response at pH > or = 7 was explained by the detection of the Hg(OH)+ cation. A normal Nernstian response was found at acidic pH values. Using these techniques, both coordination compounds, [Ligand-Hg-OH] at pH 7 and [Ligand-Hg-Ligand] at pH 4.5, were confirmed on the electrode membrane surface activated with Hg(NO3)2 solution at both pH values. These methods provide results which are independent of the potential measurement data and in agreement with them. A successful response model has explained both independent and unbiased sets of results. These conclusions confirm the proposed response mechanisms for this new Hg membrane sensor.     

Determination of arsenate in natural pH seawater using a manganese-coated gold microwire electrode

Direct electrochemical determination of arsenate (As^V) in neutral pH waters is considered impossible due to electro-inactivity of As^V. As^III on the other hand is readily plated as As⁰ on a gold electrode and quantified by anodic stripping voltammetry (ASV). We found that the reduction of As^V to As^III was mediated by elemental Mn on the electrode surface in a novel redox couple in which 2 electrons are exchanged causing the Mn to be oxidised to Mn^II. Advantage is taken of this redox couple to enable for the first time the electrochemical determination of As^V in natural waters of neutral pH including seawater by ASV using a manganese-coated gold microwire electrode. Thereto Mn is added to excess (∼1 μM Mn) to the water leading to a Mn coating during the deposition of As on the electrode at a deposition potential of −1.3 V. Deposition of As⁰ from dissolved As^V caused elemental Mn to be re-oxidised to Mn^II in a 1:1 molar ratio providing evidence for the reaction mechanism. The deposited As^V is subsequently quantified using an ASV scan. As^III interferes and should be quantified separately at a more positive deposition potential of −0.9 V. Combined inorganic As is quantified after oxidation of As^III to As^V using hypochlorite. The microwire electrode was vibrated during the deposition step to improve the sensitivity. The detection limit was 0.2 nM As^V using a deposition time of 180 s.     

Isotope identification of Langkawi black sand using neutron activation analysis

The Langkawi black sand has been analyzed using the method of neutron activation analysis (INAA). A total of 22 elements have been detected. Elements such as Mn, Cu, Cr, U and Th occur in high concentration. Prospect for future mineralization of these elements may be of economic interest.     

Determination of thorium concentrations in soil and sand samples using instrumental neutron activation analysis

Thorium along with its daughter products present in the soil is one of the major contributors to the external gamma dose in the environment. To establish the dose levels, quantification of thorium contents in soil samples is very important. As a part of pre-operational environmental radiological surveillance, a total of 23 soil and six sand samples were collected from different locations around the proposed nuclear power plant site of Jaitapur, Maharashtra. Thorium concentrations in these samples were determined by instrumental neutron activation analysis (INAA). Samples were irradiated with neutrons in Apsara reactor at a neutron flux of?~5?×?10¹¹ cm^?2 s^?1 and radioactive assay was carried out using high resolution gamma ray spectrometry. Relative method of INAA was used for quantification of thorium utilizing 311.9?keV gamma ray of ²³³Pa, the daughter product of ²³³Th. The concentrations of thorium in the soil and sand samples were in the ranges of 4.0?C18.8 and 1.2?C6.2?mg?kg^?1 respectively.     

Thermolysis and analysis of TDI char by supercritical methanol using TGA,DSC, IR and SEM

Journal of Thermal Analysis and Calorimetry - TDI's synthetic plant generates about 5 mass % of tar by phosgenation process, which has been currently a bottleneck needed to be broken through...     

Probing liquid surfaces under vacuum using SEM and ToF-SIMS

We report a newly developed self-contained interface for high-vapor pressure liquid surfaces to vacuum-based analytical instruments. It requires no wires or tubing connections to the outside of the instrument and uses a microfluidic channel with a 3 μm diameter window into the flowing fluid beneath it. This window supports the liquid against the vacuum by the liquid's surface tension and limits the high-density vapor region traversed by the probe beams to only a few microns. We demonstrate this microfluidic interface for in situ liquid surfaces in a time-of-flight secondary ion mass spectrometer (ToF-SIMS) and a scanning electron microscope (SEM) with chemical analysis.     

High-resolution, low-voltage SEM for true surface imaging and analysis

A novel design concept for the electron optical column has been implemented in the realization of a new ultra-high performance SEM. A compound magnetic/ electrostatic objective lens is at the heart of the high-performance column: the imaging aberrations of this new lens type decrease with decreasing beam energy. Any beam cross-over between the electron source (Schottky FE-gun) and the sample has been eliminated in order to avoid broadening of the beam energy spread (Boersch effect). A high beam energy is maintained throughout the column regardless of the electron probe energy selected by the operator. This protects the beam against the effect of stray fields and minimizes any loss of beam brigthness due to stochastic electron-electron interactions. The new SEM achieves outstanding resolution, particularly at the low beam energies (3 nm achievable at E_PE = 1 keV). The secondary electrons emitted by the sample are detected with very high efficiency by an internal annular detector situated above the final lens. Due to the low imaging aberration level, a high current can easily be focused in a very small probe, thus making the new SEM ideally suited for high-resolution, quantitative X-ray analysis.     

Qualitative and quantitative determination of micro-inclusions by automated SEM/EDX analysis

With the help of an automated SEM/EDX analysis system non-metallic micro-inclusions in steel can be detected on a metallographically prepared surface area. The system makes it possible to determine position, size, shape and composition of each particle. Usually more than 1000 inclusions are found on one scan area. Therefore a new offline evaluation method has been developed to classify the large amount of inclusions and calculate specific size and shape data. A summary sheet is created to show the area contents and the mean values of all important properties for each class. Size and XY distributions as well as binary and ternary phase diagrams are drawn to depict the results. The strengths of this analytical technique are demonstrated by evaluation of an LC (low-carbon) steel. Alumina, common spinel, sulfide and oxisulfide inclusions could be identified as dominant inclusion types in LC steel.     

Identification and classification of airborne soot particles using an automated SEM/EDX

Individual particle analysis by means of an automated scanning electron microscope with an energy dispersive X-ray microanalysis system (SEM/EDX) is used for chemical classification and size determination of airborne particulate matter. Special attention is paid to the X-ray analysis of atmospheric soot particles. The preparation and use of standards, which is indispensable for obtaining good results are described and discussed in detail. The aerosol samples were collected on Nuclepore filters of two different pore sizes at a traffic island in Munich.     

Preparation and characterization of in situ carbon paste and screen-printed potentiometric sensors for determination of econazole nitrate: surface analysis using SEM and EDX

The construction and performance characteristics of new sensitive and selective in situ carbon paste (ICPE) and screen-printed (ISPE) potentiometric sensors modified with ion-pairing agents such as phosphotungstic acid, sodium tetraphenylborate, phosphomolybdic acid and ammonium reineckate for determination of econazole nitrate (ECN) have been developed. The reaction mechanism between ECN and ion-pairing agents at the electrode surface was studied through scanning electron microscope and energy-dispersive X-ray analysis. The electrodes under investigation showed potentiometric response for ECN in the concentration range from 1.0 × 10^?6 to 5.0 × 10^?3 mol L^?1 and from 1.0 × 10^?6 to 1.0 × 10^?2 mol L^?1 for ISPE (electrode I) and ICPE (electrode II) potentiometric sensors, respectively, at 25 °C. The electrode response was pH independent in the range 2.5–7.5 and 2.5–6.5 for electrodes I and II, respectively. These sensors have Nernstian slope values of 59.4 ± 0.2 and 59.10 ± 0.2 mV decade^?1 with detection limit of 1.0 × 10^?6 mol L^?1 for electrodes I and II, respectively. The electrodes showed fast response time of 4 and 9 s for electrodes I and II, respectively. The ISPE (electrode I) showed lifetime of 28 days, and this was considered as advantage over ICPE (electrode II). Selectivity for ECN with respect to a number of interfering materials was also investigated. The proposed electrodes were applied for determination of ECN in pure and pharmaceutical formulation using calibration, potentiometric titration and standard addition methods. The results showed good agreement with those obtained using official method. The t and F values indicated no significant difference between the suggested and reported methods. Method validation parameters were optimized according to ICH recommendations.     

Investigation of winter atmospheric aerosol particles in downtown Katowice using XPS and SEM.

X-ray photoelectron spectroscopy (XPS) was used to determine the surface chemical composition of atmospheric particles (PM-10 and PM-2.5), collected in downtown Katowice, Upper Silesia, Poland, in the winter season (November and December 2000). Carbon- and oxygen-containing species dominated the particulate surface with traces of N, S, Si, Cl, Na, Zn, Al, Cu, Fe, Ca, K, Mg, Pb, and P present. Additionally, the size, morphology, and chemical composition of about 300 of the individual atmospheric particles were analyzed by high-resolution scanning electron microscopy and electron probe microanalysis. A number of aluminosilicates and metallic elements such as Fe, K, Mg, Zn, as well as rare earth elements, were detected by SEM. The results obtained show that the analyzed aerosol is of natural and anthropogenic origin. Particles containing sulfur compounds as well as oxygen and sodium in downtown Katowice come mainly from the east and southeast sectors.     

The use of SEM for multielement analysis in small volumes and low concentrations

Summary A preparation method is described for analysing size classified rain drops by SEM (scanning electron microscopy), equipped with an energy-dispersive detection system. The concentration is determined by addition of an internal standard. This allows the quantitative analysis of samples with a volume of 2 l and a concentration of 1 g/l. The time of measurement is 100 s.Dedicated to Professor Dr. V. Krivan on the occasion of his 60th birthday     

The impact of indium metal as a minor bimetal on the anodic dissolution and passivation performance of zinc for alkaline batteries: part I—potentiodynamic,potentiostatic, XRD,SEM, and EDAX studies

Journal of Solid State Electrochemistry - Zinc metal is an important element that can be used for long-life alkaline batteries. In this work, it is found that the addition of minor amounts of...     

Characterization of layers produced by a reactive deposition technique: An EDAX and ESCA study

Summary Zirconium containing coatings deposited by reactive sputtering on molybdenum surfaces were analysed by means of X-ray photoemission spectroscopy (ESCA) and electron-induced X-ray emission (EDAX), with an emphasis on zirconium carbide creation. For comparison ZrC layers deposited by cataphoresis were investigated. The results show that while EDAX is useful for bulk analysis of heavy atom contaminants, chemical state information vital for the reactive deposition processes is only obtained through ESCA. The spectra indicate that reactively sputtered zirconium leads to appreciable amounts of ZrC in the films only under special reaction conditions; if these are not present, unreacted Zr coatings are found, which transform to ZrO₂ upon exposure to air. By monitoring the chemically shifted Zr 3d peaks the reaction conditions in the sputtering process which are favourable for ZrC deposition were determined.

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Charakterisierung von reaktiv gesputterten Schichten durch EDAX und ESCA

     

Adsorptive removal of non-ionic surfactants from water using granite sand

The adsorption of Triton X-100 in aqueous solution on the granite sand has been investigated to evaluate its ability as an adsorbent. Various parameters such as agitation time, adsorbent dose, adsorbent size, initial concentration of adsorbate, pH, temperature, and effect of interference ions were studied on the laboratory scale to establish optimum conditions for the removal of TX-100 from the effluents of different industries. Isotherm data were analyzed for possible agreement with the Langmuir and Frendlich adsorption isotherm equations. The first order rate equation by Lagergren was tested on the kinetic data. The rate of adsorption was conformed a pseudo first order kinetics with good correlation coefficient. The value of activation energy of sorption (E_a) was obtained as 44.6 kJ mol^?1. Results showed that granite sand exhibit reasonably good surfactant removals for nonionic types. The possible role of the adsorbent in a chromatographic column was also worked out.     

Characterization of uranium particles produced by hydrolysis of UF6 using SEM and SIMS.

Environmental sampling (ES) is a powerful technique used by safeguards inspectors of the International Atomic Energy Agency and the European Safeguards Office for the detection of undeclared nuclear activities. Since its implementation in the 1990s, ES has proven to be very sensitive and effective. Considering the consequences, the measurements should be carried out under a quality management programme. At the Institute for Reference Materials and Measurements, a new production method is under development for the preparation of reference uranium particles from well-certified UF6, allowing uranium particles with certified isotopic abundances to be prepared that are representative of those found in uranium enrichment facilities. Using an aerosol deposition chamber designed and built for the purpose, particles are formed by the hydrolysis of UF6 and their morphology and (isotopic) composition measured using SEM-EDX and SIMS. The SEM measurements show that by varying the relative humidity of the air in the reaction chamber, the morphology of the particles can be changed. By making a distribution map of the chemical composition of the particles, the relationship between fluorine and uranium as main constituents of the particle could be established. The presence of fluorine is a valuable indicator for the occurrence of nondeclared enrichment activities.     

The use of chemical contrast in the SEM analysis of polymer blends

A novel method for investigating the morphology of multiphase polymers is discussed. In this procedure, inherent differences in secondary and backscattered electron emission from the various components rather than topographical variations are used to produce image contrast. The combined use of various selective stains and energy-dispersive x-ray analysis to accentuate and positively identify individual phases is discussed. The effects of coating thickness and type and changes in accelerating voltage on image quality are also described.