bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surface alteration of plagioclase during acid dissolution
Authors: Seyama Haruhiko , Kinoshita Kaoru , Soma Mitsuyuki 
Published: October 2002

AbstractTo examine the dissolution mechanism of silicate minerals in acidic solution, XPS was applied to plagioclase samples (Na0.5Ca0.5Al1.5Si2.5O8) treated with 5 × 10−2, 5 × 10−4 or 5 × 10−6 mol l−1 H2SO4 for 3 h, 1 day and 1 week. The atomic abundances of Na, Ca and Al relative to Si in the surface layer of acid‐leached (5 × 10−2 mol l−1 H2SO4) plagioclase decreased with increasing reaction time. The Si 2s and O 1s photoelectron spectra were shifted to higher binding energies during dissolution, and their binding energies were comparable to those of quartz after treatment for 1 week. From the preferential leaching of Na, Ca and Al, and the chemical shifts of the Si 2s and O 1s spectra, the formation of hydrous silicon dioxide on the mineral surface was deduced. The surface chemical composition of plagioclase changed in the same manner during dissolution by H2SO4 at a low concentration (5 × 10−4 mol l−1), although the magnitude of the decrease in surface concentrations of Na, Ca and Al was lower, suggesting the formation of a thinner altered surface layer. In addition, Al was less depleted than Na or Ca. Thus Na and Ca are more susceptible to acid leaching than Al. However, after dissolution in 5 × 10−6 mol l−1 H2SO4, the relative surface abundance of Al was slightly higher than that of the untreated sample. Surface enrichment in Al is probably associated with the formation of hydrous oxides of Si and Al. Copyright © 2002 John Wiley & Sons, Ltd.
XPS study of the reaction of chromium (VI) with mackinawite (FeS)
Authors: Boursiquot Sophie , Mullet Martine , Ehrhardt Jean‐Jacques 
Published: October 2002

AbstractIn this study, the ability of mackinawite (FeS) to reduce Cr(VI) was investigated as a function of the initial aqueous Cr(VI) concentration (1 × 10−4–5 × 10−3 M) at pH 5 and fixed ionic strength under a nitrogen atmosphere. X‐ray photoelectron spectroscopy was used to characterize the surface after reaction and to identify the oxidation products. Aqueous Cr(VI) concentration removed from solution was determined using the diphenylcarbazide colorimetric method. Mackinawite was found to act as an efficient Cr(VI) removal material. Surface analysis revealed that all detectable chromium occurred as Cr(III), even at the highest initial Cr(VI) concentration. Strong attenuation of the Fe 2p and S 2p signals from mackinawite counterbalanced the increase of the Cr 2p and O 1s levels when the initial Cr(VI) concentration increased. Clear evidence for the oxidation of Fe(II) to Fe(III), as well as hydroxylation of the surface, was provided by the Fe 2p and O 1s levels, respectively. Furthermore, the S 2p level indicated that S(‐II) was the main component, whatever the initial Cr(VI) concentration, with small amounts of polysulphides and elemental sulphur at the surface. These observations at pH 5 show that the mechanism of removal of Cr(VI) is through the reduction of Cr(VI) to Cr(III) and results in the formation of oxidation products such as Cr(OH)3 and/or FexCr(1−x)(OH)3 precipitates at the reacted mackinawite surface. Copyright © 2002 John Wiley & Sons, Ltd.
Investigation of planktonic foraminifera with ToF‐SIMS
Authors: Crone C. , Vering G. , Hönisch B. , Bijma J. , Arlinghaus H. F. 
Published: October 2002

AbstractVarious oceanic sediment properties deliver useful information for reconstructing environmental parameters of the past. Those properties that are closely related to environmental parameters are called ‘proxies’. They are measurable descriptors for desired (but unobservable) variables. Among others, promising advances were made in the field of boron isotopes in foraminiferal shells as a palaeo‐pH recorder. The isotope ratios are typically measured with thermal ionization mass spectrometry, which requires ∼200 shells to achieve high accuracy. We have investigated the possibility of using time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) for imaging single foraminiferal shells and determining their elemental and isotopic distribution. The data show that ToF‐SIMS is a useful technique for determining their elemental distribution and for measuring boron isotopic ratios with high precision in a single foraminiferal shell. The use of well‐characterized standards for calibration as well as appropriate surface cleaning procedures for foraminiferal shells should improve data accuracy. Furthermore, the data imply that the parallel detection of all masses would simplify the establishment of new proxies. Copyright © 2002 John Wiley & Sons, Ltd.
ToF‐SIMS mapping of dialkylphthalate and bisphenol‐A adsorbed on small particles
Authors: Ono N. , Sakamoto T. , Owari M. , Nihei Y. 
Published: October 2002

AbstractSmall environmental particles are believed to act as carriers of endocrine disrupters so it is very important to establish techniques for analysing such harmful organic species adsorbed on small particles.The authors examined the applicability of time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) for analysis of endocrine‐disrupting chemicals adsorbed on individual small particles in order to evaluate the technique as an environmental analytical tool. Di(2‐ethylhexyl)phthalate (DEHP), dioctylphthalate (DOP) and 2,2‐bis(4‐hydroxyphenyl)propane (bisphenol‐A or BPA) were used as model compounds. All of them are suspected to be endocrine‐disrupting chemicals.First, about one monolayer of each compound was adsorbed on a flat substrate instead of particles, and the mass spectra were measured. Next, DEHP or BPA was adsorbed on 6.8 µm silica particles and ToF‐SIMS spectral mapping was performed. From each spectral map, ToF‐SIMS spectra from a single particle area were extracted.The ToF‐SIMS spectra from actual environmental particles, which adsorb many different kinds of compounds together, are expected to be very much complicated. It seems almost impossible to identify all the compounds. However, if a few expected compounds show strong and characteristic fragment peaks, ToF‐SIMS might be a very powerful tool to analyse the distribution of the compounds. In the study of the fate of endocrine‐disrupting chemicals, very important information such as the relationship between the compound and its carrier particles will be obtained from ToF‐SIMS analysis. Copyright © 2002 John Wiley & Sons, Ltd.
Study of long‐term corrosion layers grown on high‐tin leaded bronzes by means of the combined use of GDOES and SEM + EDS
Authors: Ingo G. M. , Angelini E. , Bultrini G. , Calliari I. , Dabala M. , De Caro T. 
Published: October 2002

AbstractGlow discharge optical emission spectrometry (GDOES) and scanning electron microscopy + energy‐dispersive spectrometry (SEM + EDS) are used for studying the microchemistry of the long‐term corrosion products, i.e. the patina, on archaeological high‐tin leaded bronzes used by Romans, most likely as mirrors. The results show that via GDOES it is possible to obtain reliable and detailed elemental composition–depth profiles for the corrosion products of the patina and for the bulk chemical composition of the bronzes that are in good agreement with the microchemical features obtained via SEM + EDS. The results provide good insight into the corrosion layers, showing copper and lead selective corrosion and depletion phenomena leading to the formation of a complex microchemical structure and, further, showing clearly the interaction between the inorganic and organic constituents of the soil, such as iron, silicon and phosphorus, in contact with the corrosion products grown on the bronzes. Finally, the results show that GDOES, with its ability of routine and rapid analysis of layers of thickness up to 150 µm, in combination with SEM + EDS, has significant potential in studies of the corrosion products for the restoration and conservation of ancient high‐tin leaded bronzes. Copyright © 2002 John Wiley & Sons, Ltd.
X‐ray mapping of microstructures in hardmetals and cermets
Authors: Wollein B. , Bohn M. , Lengauer W. 
Published: October 2002

AbstractHardmetals and cermets are alloys with a complicated microstructure of hard‐phase constituents such as WC, TiC, TiN,… and its combinations. A variety of microstructural constituents can form in these alloys, which define their performance to a large extent. Some hard‐phase particles occur in a core‐and‐rim type structure in which the element concentration differs substantially between the core and the rim. In order to investigate the microstructural features of hardmetals and cermets in detail, model alloys in the form of diffusion couples were prepared. X‐ray investigations using state‐of‐the‐art wavelength‐dispersive x‐ray mapping procedures implemented on a Cameca SX 50 microprobe were performed for all the elements, both light and heavy, occurring in these alloys. Line coincidences were treated by comparison with chemically analysed standards and by subtracting interfering radiations.After 1008 h, W‐rich rims were found around Ti‐rich cores inside the Ti(C,N) phase of the Ti(C,N)/(Ti,W)C diffusion couple. The thickness of these rims did not change with time. When W was substituted by Mo it was observed that the well‐known core–rim structure is built by diffusion of Mo into the Ti(C,N) grains. But with time the Mo diffuses into the core of the Ti(C,N) phase and homogenizes, showing that the core–rim structure is not stable. Copyright © 2002 John Wiley & Sons, Ltd.
Application of AFM in microscopy and fabrication of micro/nanostructures
Authors: Lopour F. , Kalousek R. , Škoda D. , Spousta J. , Matějka F. , Šikola T. 
Published: October 2002

AbstractIn the paper atomic force microscopy (AFM) studies of microstructures made by ion beams on Si and Au surfaces and by AFM local anodic oxidation on Ti thin films is presented. By using the AFM technique, etching limits of inert atoms in the production of silicon and silver grids were found. It was proved that the height of Ti oxide lines fabricated by AFM increases linearly with the voltage between a tip and a sample. On the other hand, the half‐width of the lines did not depend linearly on this voltage. The results are useful for experiments in the fabrication of nanoelectronic devices (e.g. single‐electron transistors). Copyright © 2002 John Wiley & Sons, Ltd.
A new method of thin gate SiO2 reliability characterization
Authors: Liu Hongxia , Hao Yue 
Published: October 2002

AbstractTime‐dependent dielectric breakdown (TDDB) of thin gate oxides is an important reliability issue of MOS integrated circuits. Breakdown characteristics of thin gate oxides are measured under constant voltage stress (CVS). Effects of the gate voltage and gate oxide area on charge to breakdown Qbd are discussed. The experimental results show that Qbd is not a constant; Qbd depends on both the gate oxide area and stress voltage and cannot act as the breakdown criterion over a wider stress range. Based on experimental results, a novel empirical power law is proposed to characterize thin gate oxide reliability and the correlated parameters are fitted. The empirical power law has been used in extrapolations to obtain Qbd for an arbitrary oxide area and gate voltage. Extrapolated results are in good agreement with those measured at constant voltage, so it is a useful tool for predicting thin gate oxide reliability. Copyright © 2002 John Wiley & Sons, Ltd.
Structure of Gd2O3 films epitaxially grown on GaAs(100) and GaN(0001) surfaces
Authors: Flückiger T. , Erbudak M. , Hensch A. , Weisskopf Y. , Hong M. , Kortan A. R. 
Published: October 2002

AbstractAtomically thin films of Gd2O3 grow on GaAs(100) in the cubic α‐Mn2O3 structure exposing the (110) surface. The film disorders upon brief sputtering with 1000 eV Ar+ ions for 10 s. Subsequent annealing of the sample at 700 K restores the crystalline structure, however, with fourfold symmetry. Core‐level binding energy shifts show that the chemical states of all four components change upon sputtering and change further upon annealing. This observation is consistent with breaking and subsequent restoring of the chemical bonds at the Gd2O3/GaAs interface during surface processes until a new compound is formed. The Gd2O3 films grown on GaN(111) are stabilized in the high‐temperature hexagonal phase exposing their sixfold symmetric surface. Secondary electron imaging patterns recorded during sequential sputtering reveal that there is a high degree of rotational alignment of crystallographic features at the Gd2O3/GaN interface. Copyright © 2002 John Wiley & Sons, Ltd.
Single‐crystal LiNbO3 surfaces processed in low‐temperature hydrogen plasma: XPS, REELS and AFM study
Authors: Turčičová H. , Zemek J. , Tóth J. , Drbohlav I. 
Published: October 2002

AbstractSingle crystals of lithium niobate, which is a widely used material in opto‐electronics, holography, surface acoustic wave devices, etc., have been processed in a low‐temperature plasma of radiofrequency discharge in hydrogen. The aim was to examine a new kind of surface modification of LiNbO3. The surface modification has been studied by XPS, reflection electron energy‐loss spectroscopy (REELS) and atomic force microscopy (AFM). The XPS study via the Nb 3d spectral lineshape revealed the plasma effect: a decomposition of the niobate structure and the appearance of niobium oxides. The subsequent REELS study performed at 4 keV electron energy showed a transfer of characteristic electron‐loss energies of relevant transitions. Oxygen and lithium escape from the surface and hydrogen is incorporated from the plasma, producing niobium hydride. The deterioration of the niobate unit cells is accompanied by an enhancement of conduction electrons. The subsequent thermal reoxidation in medical oxygen did not restore the original niobate structure. The surface morphology after the reoxidation is characterized by elongated 100 nm grains situated normally to the surface. The main constituents of this new top layers are niobium oxides Nb2O5 and NbO. The present results form part of a complex study of the plasma modification of lithium niobate. The plasma processing induces lattice defects that are similar to those of ion implantation or metal ion doping: the electrical and optical properties of the surface layer drastically differ from those of the bulk. Copyright © 2002 John Wiley & Sons, Ltd.
Quantification of oxide film thickness at the surface of aluminium using XPS
Authors: Alexander M. R. , Thompson G. E. , Zhou X. , Beamson G. , Fairley N. 
Published: October 2002

AbstractOxide films grown anodically at the surface of superpure aluminium are used as standards to assess the accuracy of the thickness (dXPS) determined using the Beer–Lambert treatment of the Al 2p metal and oxide peak intensities. For the fitting conditions employed, the value of dXPS is found to be very close to the true film thickness for films <10 nm thick, beyond which imprecise values are obtained. A surface layer of hydration is identified from the curve fitting of the O 1s core level, which would qualitatively account for the slight underestimate of film thickness provided by the expression for dXPS. The validity of the Al 2p fit may be determined through this correlation of thickness but requires first a quantitative assessment of the thickness and composition of the hydroxide‐rich layer. Copyright © 2002 John Wiley & Sons, Ltd.
Dynamic segregation during ferrite oxidation revealed by XPS
Authors: Domenichini B. , Amilain‐Basset K. , Bourgeois S. 
Published: October 2002

AbstractDynamic segregation phenomena were revealed by XPS during the oxidation of some ferrites (Fe2.5Ti0.5O4, Fe2.5Ni0.5O4, Fe2CrO4 and FeCr2O4). This kind of phenomenon induces, at a low temperature (below room temperature), drastic changes in the cationic composition of the most external layers. Dynamic segregation is a function of the cationic composition, the oxidation capability and the morphology of these ferrites. Although dynamic segregation seems to be a quite frequent phenomenon that often can be observed during ferrite oxidation, there are materials in existence where it does not appear, such as molybdenum ferrite. Copyright © 2002 John Wiley & Sons, Ltd.
Stabilization of polar solid oxide surfaces: competition between adsorption and reconstruction
Authors: Domenichini Bruno , Pataut Gaël , Bourgeois Sylvie 
Published: October 2002

AbstractMulti‐cationic spinel compounds are solids that exhibit polar faces. X‐ray Photoelectron spectroscopy revealed the main phenomena allowing the stabilization of these faces, carried out as a function of the material treatment, particularly the cooling rate after thermal treatment at a high temperature (1200°C). This study showed that, whatever the cooling rate, each sample is subject to a significant hydroxylation that reduces the polarity. Nevertheless, it appears that the hydroxyl group content at the surface is a strong function of the cooling rate. Indeed, whereas quenched materials are subject to high levels of hydroxylation, slowly cooled samples are sparingly hydroxylated. This phenomenon corresponds to the fact that, during a slow cooling down, a change of the cationic composition in the topmost layers of the solids is able to occur, inducing a decrease of the polarity. Moreover, this segregation comes with a change of the grain surface morphology, leading to less polar faces. Copyright © 2002 John Wiley & Sons, Ltd.
Characterization of additives at polymer surfaces by ToF‐SIMS
Authors: Médard N. , Poleunis C. , Eynde X. Vanden , Bertrand P. 
Published: October 2002

AbstractIn order to test the possibility of additive concentration quantification based on SIMS data, model samples were prepared. Samples consisted of thin polymer layers deposited by spin coating from solutions containing controlled amounts of selected additives. After identification of the main characteristic additive peaks, the SIMS intensity measured on these samples was compared with the bulk additive concentration. Our results showed that for the Irgafos 168–Hostavin N30 mixtures a linear relationship was found between SIMS intensity ratio and bulk composition. Thus, no synergy effect was detected when these additives are mixed together. However, for Irgafos 168 in copolymer PETi no linearity was observed. The data, based either on relative intensity or on multivariate statistical analysis (principal component analysis), indicated a strong segregation of the additive at the surface, i.e. a possible synergy effect with the polymer matrix. Finally, it appears that the segregation effect depended greatly on the nature of the additive and the polymer because, for the same bulk concentration, copper phthalocyanine in PETi and Irgafos 168 or Irganox 1010 in atactic polypropylene were barely detected. Copyright © 2002 John Wiley & Sons, Ltd.
Surface chemical derivatization of plasma‐treated PET and PTFE
Authors: Markkula T. K. , Hunt J. A. , Pu F. R. , Williams R. L. 
Published: October 2002

AbstractSurfaces of two widely used biomaterials—poly(tetrafluoroethylene) (PTFE) and poly(ethylene terephthalate) (PET)—have been modified using gas plasmas. The concentrations of hydroxyl, carboxyl, carbonyl and amine groups were analysed with chemical derivatization (CD), using different aldehyde, acetic anhydride, alcohol and hydrazine reagents, and SIMS. Quantification was done by comparing the CD/SIMS results with XPS atomic ratios. Ammonia helical resonator plasma (HRP) treatment was found to incorporate mainly amine and hydroxyl groups on both materials. Argon HRP treatment of PTFE and nitrogen capacitor plate plasma (CPP) treatment of PET were found to increase carboxylic functionalities. The double‐bonded oxygen of the ester group of the unmodified PET was attacked and transformed to other groups in the order ammoniaplasma > nitrogenHRP > nitrogen CPP, with carbonyl content being reduced to 2.6, 4.1, and 7.6 respectively from 13.5 groups per 100 carbon atoms of the untreated PET. Chemical derivatization greatly helped to distinguish between the functional groups on the plasma‐treated surfaces. The difference between the surface specificity of SIMS and XPS has been discussed in the light of these results. Copyright © 2002 John Wiley & Sons, Ltd.
Thiophene‐containing organometallic polymers studied by near‐edge x‐ray absorption spectroscopy
Authors: Polzonetti G. , Iucci G. , Altamura P. , Ferri A. , Paolucci G. , Goldoni A. , Parent Ph. , Laffon C. , Russo M.V. 
Published: October 2002

AbstractA near‐edge x‐ray absorption fine structure (NEXAFS) spectroscopy investigation on the electronic structure of some novel π‐conjugated organometallic polymers is presented. The investigated materials consist of Pt and Pd(II) complex units linked together through σ‐bonded organic spacers of ethynyl‐thiophene type in a polymeric array.The C K‐edge NEXAFS spectra were interpreted by comparison with literature data and with the spectra of reference samples. The linking between the thiophene rings and alkyne groups produces a splitting of the C 1s → π* peak observed in the spectra of the thiophene systems. Angle‐dependent measurements, performed at normal and grazing incidence of the linearly polarized photons, evidenced a preferential orientation of the polymer chains with an average tilt angle of 45° for the thiophene moieties. Copyright © 2002 John Wiley & Sons, Ltd.
Quantifying the cathodoluminescence generated in ZnS‐based phosphor powders
Authors: Greeff A. P. , Swart H. C. 
Published: October 2002

AbstractField emission displays (FEDs) are a possible alternative to other display technologies. They work similar to cathode ray tubes, but instead of an electron gun they have an array of tiny metallic tips acting as electron emitters. This array is situated in close proximity to the phosphor screen and produces light by a process of cathodoluminescence (CL). During prolonged electron beam irradiation a non‐luminescent ZnO layer forms on the irradiated surface of the ZnS phosphor powder. This is due to electron‐beam‐stimulated surface chemical reactions between the ZnS phosphor and water vapour present in the ultrahigh vacuum environment. The low‐energy electrons used in FEDs have a shallow penetration depth and, because the CL is dependent upon the energy loss in the ZnS bulk itself, growth of the ZnO layer significantly degrades the CL intensity. Energy loss profiles in the ZnS for different ZnO thicknesses were determined using Monte‐Carlo electron trajectory simulations. These profiles, along with photon absorption profiles, were used to determine a curve relating the normalized CL intensity to the ZnO thickness. It was compared with experimentally measured values obtained during CL degradation experiments on standard ZnS : Cu,Al,Au phosphor powders and ZnO thickness measurements with sputter depth profiling. Assuming the presence of a 20 nm thick diffusion interface between the ZnO layer and the ZnS bulk, the theoretical and experimental results agree well. Initially the interface represents the initial stages of oxidation, but after the oxide layer starts to grow as a uniform film it represents a physical interface formed due to diffusion processes. Copyright © 2002 John Wiley & Sons, Ltd.