bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prolonged lifetime of electrochromism of amorphous WO3–TiO2 thin films
Authors: Hashimoto Satoshi , Matsuoka Hideki 
Published: December 2004

AbstractThe lifetime of the electrochromism of the WO3–TiO2 films prepared by vacuum evaporation is found to exceed that of WO3 films by a factor of five. X‐ray diffraction has revealed that the crystal structure of WO3–TiO2 films stays amorphous, while crystalline compounds are formed in amorphous WO3 films after colouring and bleaching. WO3–TiO2 films stay amorphous after they are annealed at 400°C, although WO3 films crystallize. SIMS and XPS analyses have revealed that half the amount of lithium injected during a colouring cycle is stored as OLi bonds in the bleached film. In WO3–TiO2 films the number of bonds such as WOH and WO in which lithium ions accumulate is reduced. We conclude that the lifetime of the electrochromism is prolonged for amorphous WO3–TiO2 films, because lithium does not accumulate and the WO3–TiO2 films stay amorphous.
The frontiers of surface structure analysis
Authors: Somorjai G. A. 
Published: December 2004

AbstractLow‐energy electrons have been used predominantly to determine surface structure: low‐energy electron diffraction (LEED) surface crystallography to identify the location of surface atoms and molecules, their site symmetry, bond distances and bond angles; and high‐resolution electron energy‐loss spectroscopy (HREELS) to determine the vibrational spectra of atoms and molecules at surfaces. The key findings of research using LEED and HREELS will be discussed. The new directions of research using these two techniques for studies of disordered surface layers and more complex molecules will be reviewed.Scanning tunneling microscopy (STM) and atomic force microscopy are new techniques under rapid development for surface structure determination. The combination of STM and LEED crystallography permits the quantitative validation of STM findings. Atomic spatial resolution uncovered several unexpected surface structures. The use of STM during high‐pressure catalytic reactions is at the frontier of surface structure studies.Extended x‐ray adsorption fine structure (EXAFS) and photoelectron diffraction have been used to study the atomic structure and coordination of clusters. Laser sum frequency generation (SFG) is employed to obtain vibrational spectra of molecules at solid/liquid and solid/solid interfaces. These techniques expand the frontiers of surface structure analysis to new types of surface and interface systems.
Properties of surface‐modified alumina catalysts of COS synthesis
Authors: Auroux A. , Gervasini A. , Németh L. , Gáti G. , Pap I. S. , Mink G. 
Published: December 2004

AbstractThe surface electronic structure, the acid–base properties, the component adsorption and the catalytic activity of gamma alumina (CK‐300, Ketjen) modified with surface sodium as a donor‐type or iron as an acceptor‐type additive have been investigated. Alumina was loaded with 0.1 and 1 wt.% Na and Fe. The catalytic O/S exchange of CO2 and CS2 to form COS was applied as a model reaction, for which the kinetic parameters have also been determined. In the case of unloaded alumina and samples loaded with 0.1 wt.% Na and 0.1 or 1.0% Fe no characteristic differences in the shape and position of the O 1s and Al 2p lines were observed. However, 1.0 wt.% Na loading resulted in a broadening of the O 1s and Al 2p lines towards lower binding energies. Sodium, even in 1% monolayer coverage, and other donor‐type surface species, e.g. pre‐adsorbed NH3 or pyridine, exhibited a readily detectable promoter effect which could be characterized by increased surface basicity, increased CO2 and CS2 adsorption and better catalytic performance. In contrast, on catalysts loaded with Fe an increase in surface acidic sites, a loss of basic sites, decreased component adsorption and lower catalytic activity were observed.
Scattering in electron spectrometers, diagnosis and avoidance. II. Cylindrical mirror analysers
Authors: Seah M. P. 
Published: December 2004

AbstractAn analysis is made of the effects leading to an unwanted scattered background of electrons in cylindrical mirror analysers (CMAs). This work complements that given in Part I on concentric hemispherical analysers. It is shown that scattering from the middle region of the inner surface of the mirror electrode is significant but that the amount of scattering reaching the detector may be reduced by reducing the area of the output slit or by adding a deflection post filter to the optics as occurs in some commercial instruments. Internal scattering causes a higher background so that peak‐to‐background ratios are attenuated and transmission function calibrations involve a systematic error. Evidence for this error is a step in the calibration curves for I(E)/En(E) established earlier. The steps appearing in the curves for Cu and Ag reference samples give a direct measure of the scattering intensity. Calibration plots are established for this purpose. Results from previous interlaboratory comparisons are analysed showing that in commercial CMAs with large‐area energy selection slits the scattering may reach 35% of the copper true background at 950 eV, complicating the subsequent use of the data. Concentric hemispherical analysers and some commercial CMAs show very low scattering. In some CMAs the analogue detection systems cause a similar enhanced background in addition to scattering, boosting the above figure of 35% to 100%.
Determination of the distribution of chromium oxidation states in reduced Cr/Al2O3 catalysts from XPS by factor analysis and curve fitting
Authors: Scierka Stephanie J. , Proctor Andrew , Houalla Marwan , Fiedor Joseph N. , Hercules David M. 
Published: December 2004

AbstractPrincipal component analysis (PCA) and target testing (TT) were performed on a series of reduced 2.5 wt.% Cr/Al2O3 catalysts to determine the number, positions, shapes and relative spectral compositions (i.e. Cr oxidation states) in Cr 2p spectra as monitored by ESCA. The results from PCA indicated the presence of only two abstract components. The abstract factors were transformed through iterative TT into real spectroscopic components that were attributed to Cr6+ and Cr3+. These factor analysis results were used in addition to non‐linear least‐squares curve fitting to provide a detailed description of changes in the Cr 2p envelope during reduction of the Cr/Al2O3 catalysts. Only two components were necessary to reproduce the original data.
Determination of attenuation lengths of photoelectrons in aluminium and aluminium oxide by angle‐dependent x‐ray photoelectron spectroscopy
Authors: Marcus P. , Hinnen C. , Olefjord I. 
Published: December 2004

AbstractAngle‐dependent x‐ray photoelectron spectroscopy (AD‐XPS) measurements have been carried out on thin aluminium oxide layers formed on pure aluminium by oxidation in oxygen at 25°C and at 250°C. The amounts of oxygen of the oxide overlayers were measured by nuclear reaction analysis (NRA). The equipment thicknesses of the oxide layers were 14 Å and 21.5 Å for the oxides formed at 25°C and at 250°C, respectively. The AD‐XPS measurements were carried out in the range of take‐off angles 12–122°.The signals emitted by Al3+ in the oxide and by Alm in the metal versus take‐off angle can be, within experimental error, fittex by an exponential function in the range of take‐off angles ∼30–120°. This confirms the applicability of an exponential law for the attenuation of photoelectrons for the studied system in the range of take‐off angles ∼30–120°. The AD‐XPS measurements were used to determine the attenuation lengths of the electrons emitted by aluminium (kinetic energy ∼1180 eV) in the oxide (λox) and in the metal (λm). The attenuation lengths derived from the experiments are: λox = 20 Å and λm = 18 Å. These values are lower than the theoretical inelastic mean free paths owing to the contribution of elastic scattering. For the lowest investigated take‐off angles (<30°) the measurements deviate from the exponential law. The deviation is attributed to the effects of elastic scattering and of the angle of acceptance of the photoelectrons.As a complement to this work, an intercomparison of AD‐XPS measurements was performed in four laboratories on the two reference samples. In the range of take‐off angles 40–120°, the results can be fitted by the exponential law for the attenuation of the photoelectrons. However, differences of 10–20% were observed in the apparent overlayer thickness. Careful analysis of the data revealed that this was primarily caused by a systematic error introduced in the peak fitting when a symmetrical peak is used, instead of an asymmetrical peak, for the Alm signal.
Automatic removal of substrate backscattering effects in Auger imaging and spectroscopy
Authors: Barkshire I. R. , Prutton M. , Greenwood J. C. , El Gomati M. M. 
Published: December 2004

AbstractThe York multi‐spectral scanning Auger microscope has been used to investigate the correlations between Auger and backscattered electron images collected simultaneously from a electron spectrometer and the quadrants of a Sip‐n junction backscattered electron detector. Digital signal processing of the four backscattered electron signals allows the calculation of the Auger backscattering factor at each pixel position, the division of which into the Auger image allows the removal of contrast due to subsurface composition variations. The method, which allows the quantification of complicated heterogeneous samples, requires no fitting parameters or prior knowledge regarding the sample.
Comparison of validity and consistency of methods for quantitative XPS peak analysis
Authors: Tougaard S. , Jansson C. 
Published: December 2004

AbstractIn the present work, we have tested the consistency and validity of the Tougaard, Shirley and straight‐line methods for determination of peak intensities in XPS. Intensities were determined from essentially all photoelectron peaks (with Mg Kα and Al Kα radiation) from seven polycrystalline elemental solids (Co, Ni, Cu, Zn, Ag, Pt and Au) and for three sets of polycrystalline alloys (Cu0.75Au0.25, Cu0.5Au0.5, Cu0.25Au0.75, and Co0.75Ni0.25, Co0.5Ni0.5, Co0.45Ni0.55, Co0.25Ni0.75 and Cu0.55Ni0.44Mn0.01). For the three methods, the consistency of the peak intensity ratios determined under a variation of analyser settings was studied. The validity of the three methods was studied by comparison of peak intensity ratios to two sets of theoretical photoionization cross‐sections (due to Scofield and Band et al., respectively). The inelastic electron mean free paths were taken from theoretical tabulations when available or from analytical expressions (both due to Tanuma et al.).The Tougaard method is found to be superior to the Shirley and straight‐line methods, both with respect to consistency and validity. For a selected set of peaks where the error on theory is minimal, the deviation from theory is 3% for the Tougaard method and 33–60% for the Shirley and straight‐line methods. Considering all XPS peaks from seven metals, the root‐mean‐square deviation from theory for the Tougaard method is found to be ∼11% for the ratios of peak intensities to a peak from the same solid and ∼14% for the ratios of peak intensities to the Au 4d peak intensity. These deviations fall within the expected accuracy of theory. The corresponding root‐mean‐square deviations from theory for the Shirley and straight‐line methods are found to be 35% and 25%, respectively. For alloys, the Tougaard method gives the most consistent description of the shake‐up electrons. For the Shirley and straight‐line methods applied to spin‐orbit doublet peaks, the accuracy is in general worse than the above.
Use of Zr− secondary ion energy distributions and factor analysis to construct chemical‐state depth profiles in SIMS
Authors: Splinter S. J. , van der Heide P. A. W. , Lin A. , McIntyre N. S. 
Published: December 2004

AbstractFactor analysis (FA), the multivariate statistical technique, has been used to extract chemical bonding information from SIMS secondary ion energy distributions. The method is outlined in detail and shown to be capable of constructing quantitative profiles for the chemical states of zirconium present in ZrO2/Zr and ZrNx/Zr structures. In addition, a truncated data collection procedure wherein secondary ion intensity values are collected at a fixed number of emission energy values during the depth profile is outlined. This method, which enables data to be collected in a shorter time and from a smaller sample volume, is subsequently shown to yield reliable results, as confirmed by FA of Auger depth profiles on similar specimens.
Feasibility of quantitative analysis of metals and alloys by non‐resonant multiphoton ionization of sputtered neutral species
Authors: Scrivener E. , Wilson R. C. , Vickerman J. C. 
Published: December 2004

AbstractA system for non‐resonant multiphoton ionization (NRMPI) of suttered neutral species has been developed. The instrumentation is based on a Kratos time‐of‐flight SIMS system with a dual‐stage ion reflectron. Ionization of sputtered neutral species is provided by a focused excimer laser beam of wavelength 193 nm.Two basic operational procedures are defined that involve using either a continuous or pulsed primary ion beam for sputtering. The consequences of each mode on the resulting spectrum are considered. Characterization experiments are reported that show the effect of laser flux on the yields of elemental and molecular species, allowing conditions to be selected for subsequent experiments. The laser flux profiles demonstrate that saturation of the ionization process is easily achieved for most species studied. Relative sensitivity factors (RSFs) from elements in standard metal alloy samples are presented that suggest that some effect of matrix is present. However, reproducibility of RSFs between consecutive runs and between the pulsed and continuous modes of bombardment is very good (<10% and even <5% in some cases) for the majority of species. Values for the useful yield and detection limit in NRMPI and SIMS are compared.
Reactive ion sputter depth profiling of tantalum oxides: A comparative study using ToF‐SIMS and laser‐SNMS
Authors: Franzreb K. , Mathieu H. J. , Landolt D. 
Published: December 2004

AbstractA time‐of‐flight (ToF) suptter depth profile analysis of standard 15 or 30 nm thick anodically formed Ta2O5 layers as well as of the naturally grown ∼2 nm thin oxide overlayer on metallic tantalum samples has been made using both the techniques of (positive and negative) secondary ion mass spectrometry (SIMS) and laser secondary neutral mass spectrometry (Laser‐SNMS). Specific emphasis of this comparative study is on the characterization of the performance of a state‐of‐the‐art ToF mass spectrometer with respect to sputter depth profiling. The prospects of SIMS and Laser‐SNMS for quantitative near‐surface analysis are addressed under special consideration of reactive (Cs+ or Ga+) ion beam sputtering applied in the present work.
Aqueous finishing of vinyl film. I. Film properties
Authors: Cluthe C. E. , Goth S. , Martorano R. 
Published: December 2004

AbstractMuch of the coating industry has converted to water‐based substitutes in order to reduce organic emissions and to improve safety and employee environment. Recently the vinyl industry has shown an increased interest in alternative coating systems, particularly those based on water. Replacing solvent‐based gravure coatings with water‐borne materials presents many technical problems, not the least of which are maintenance of gravure printability and physical properties. Our studies on lower plasticizer containing grades of vinyl, primarily wallcovering, have culminated in the development of an aqueous model based on a room temperature crosslinking emulsion with resistance properties suitable for this application.
The effect of formulation variables on smoke evolution of plasticized PVC during combustion
Authors: Price Roger V. 
Published: December 2004

AbstractUsing an NBS smoke test chamber, smoke evolution of a variety of plasticized and filled PVC formulations is studied. The lowest smoke evolution was provided by the joint use of alkylaryl phosphates and magnesium carbonate. Partial replacement of triaryl phosphates by chlorinated paraffins reduces significantly smoke evolution in the flaming mode without effect from antimony oxide.
Interaction effects and property retention in poly(vinyl chloride) compounds
Authors: Schreiber H. P. , Checkland J. 
Published: December 2004

AbstractThe influence of thermodynamic interactions among the components of a polymer system on mechanical properties and their retention on aging has been investigated. The systems considered involve plasticized poly(vinyl chloride)(PVC), and CaCO3 fillers. Inverse gas chromatography was used to measure interaction parameters, and to express these in terms of acid‐base concepts. Interaction data were obtained over a wide temperature range. It was shown that the volume of plasticizers retained by the PVC correlates with the measured interaction parameters. Similarly, the interaction parameters identify a CaCO3 filler preferred for reinforcing rigid PVC, and a different CaCO3 filler for use in given PVC‐plasticizer combinations. The mechanical properties of filled PVC (up to 40 phr CaCO3), and particularly the ultimate properties of the compounds, correlate with interaction concepts, as do property retention data after accelerated aging of the compounds at 100°C. It is concluded that component interaction parameters may provide useful guidelines to the formulation of compounds with superior properties and reduced property losses due to aging.
Measurement of PVC fusion (gelation)
Authors: Summers James W. , Rabinovitch Elvira B. , Booth Patrick C. 
Published: December 2004

AbstractPVC fusion (gelation) occurs with melting of crystallites followed by recrystallization. This recrystallization, as it occurs at the primary particle boundary, physically ties together the structure into a three dimensional network. One way of measuring the extent of this three dimensional network structure is to measure the force required to deform the material through a zero land length capillary. We examine this test method for various molecular weight PVC compounds, with and without plasticizer, and for various degrees of grinding the product.
Rheology of flexible PVC compounds. Part I: The influence of resin crystallinity
Authors: Smith D. L. , Hookanson S. H. , Irvine J. L. 
Published: December 2004

AbstractThe changes occurring in torque during PVC processing in a torque rheometer have been interpreted in terms of the destruction of the supramolecular structure followed by a fusion of the grain fragments. In contrast to changes in torque, changes in elasticity occur in the absence of grain breakdown. It is proposed that the change in elasticity during processing is the result of changing crystallinity of the resin. In the early stages of processing, crystallites melt and elasticity decreases. As grains fuse together, new crystallites are formed in the previously unoccupied grain boundaries and the elasticity increases.
History of the development of processing aids for rigid PVC
Authors: Dunkelberger David L. 
Published: December 2004

AbstractBauman's polymerization of vinylchloride is generally regarded as the first documented preparation. British and German patents were granted in 1912 but the period from 1931 to 1933 based on work at BFGoodrich is considered as the beginnings of the flexible PVC industry, which grew rapidly during the 1940's and 1950's to become the dominant family of synthetic plastic resins. However, PVC degrades at about the same temperature required to process it. Therefore, without stabilizers and other additive modification, it could not have reached its present preeminence among rigid thermoplastics. The first processing aid patent appeared in 1953, and the first commercial processing aid appeared in 1957, which marked the beginning of the rigid PVC industry, the development of which is described in the paper.
Study of the effect of fumed silica on rigid PVC properties
Authors: Fellahi Said , Boukobbal Saadi , Boudjenana Farid 
Published: December 2004

AbstractThis study seeks to substitute fumed silica for chlorinated polyethylene (CPE) within a rigid PVC formulation intended for profile extrusion such as doors and window frames. The effect of fumed silica on both mechanical (tensile and impact) and thermal (Vicat point, HDT, and linear thermal expansion coefficient) properties were investigated. Five rigid PVC formulations were prepared, including a reference one (F1), then F1 with CPE, F1 with untreated silica, F1 with heat treated silica, and finally F1 with dried silica and a coupling agent. The effect of CPE on mechanical properties was very modest. On the other hand, CPE showed its inefficiency, in that HDT and Vicat point were decreased. Heat treated silica showed the greatest improvement in both mechanical and thermal properties. Untreated silica showed a small effect on both properties. Finally, the incorporation of coupling agent gave considerable improvement in both mechanical and thermal properties.
Performance of hybrid reinforcements in PVC composites. II: Use of surface‐modified mica and different cellulosic materials as reinforcements
Authors: Maldas D. , Kokta B. V. 
Published: December 2004

AbstractThe effect of the composition of various wood fibers and surface‐treated mica as well as different surface treatments of cellulosic materials on the mechanical properties of PVC composites has been evaluated. Cellulosics were surface modified by prior coating with maleic andydride (MA), mixtures of MA and Na‐silicate and isocyanate. The filler concentration was fixed at 25 wt%. Both tensile strength and modulus of composities filled solely with mica are superior to those of non‐treated wood fiber‐filled composities. while the reverse is true for impact strength (except for bagasse‐filled composities), ultimate elongation, and tensile toughness. Moreover, the mechanical properties of composities, with the exception of modulus, filled only with mica and/or non‐treated wood fibers are inferior to those of unfilled PVC. Compared to non‐treated fiber‐filled composites, properties improved when surface‐modified wood fibers were used alone, or along with mica. Isocyanate‐coated wood fibers ranked best with regard to the mechanical properties of the composities. Properties also changed with the change of wood species and compositions of mica and wood fibers. Experimental results indicate good compatibility between surface‐treated wood fibers/mica and PVC composities.