Nowa wersja platformy, zawierająca wyłącznie zasoby pełnotekstowe, jest już dostępna.
Przejdź na https://bibliotekanauki.pl
Ograniczanie wyników
Czasopisma help
Lata help
Autorzy help
Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 104

Liczba wyników na stronie
first rewind previous Strona / 6 next fast forward last
Wyniki wyszukiwania
Wyszukiwano:
w słowach kluczowych:  XPS
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 6 next fast forward last
1
Content available remote Termoizolacja z polistyrenu ekstrudowanego XPS
100%
PL
W artykule podstawowe informacje o tym czym jest polistyren ekstrudowany, określany także jako XPS, jak jest wytwarzany, czym różni się od styropianu oraz o tym jakie ma właściwości fizykochemiczne i użytkowe.
PL
Technika XPS (X-ray Phothoelectron Spectroscopy) znana również jako ESCA (Electron Spectroscopy for Chemical Analysis) jest bardzo szeroko stosowana do badań ilościowych składu chemicznego powierzchni ciał stałych. Możliwość eksplorowania jedynie kilku pierwszych warstw atomowych powierzchni ciała oraz przyporządkowywania wykrywanym atomom ich stanu chemicznego czyni tę metodę ważnym narzędziem w każdym laboratorium analitycznym, jednak szczególnie predestynuje ją do badań zjawisk adsorpcji i katalizy heterogenicznej. W tej publikacji dokonano krótkiego przeglądu możliwości analitycznych techniką XPS wraz z przykładem identyfikacji monolitycznego katalizatora wanadowego na nośniku z folii A1Ti do Selektywnej Redukcji Katalitycznej (SCR) tlenków azotu za pomocą amoniaku. Na jego powierzchni wykryto i określono stężenie trzech tlenków wanadu Y2Os, YO2, i Y2O3. Wykazano, że obecność V4+ sprzyja większej aktywności katalizatora.
EN
X-ray Photoelectron Spectroscopy (XPS) also known as Electron Spectroscopy for Chemical Analysis (ESCA), is widely used to investigate the chemical composition of surfaces. The ability to explore the first few atomic layers and assign chemical states to the detected atoms has shown XPS to be a powerful addition to any analytical laboratory. Same examples of surface analysis were presented. Particularly new vanadium monolithic catalyst on metallic carrier of AITi alloy for Selective Catalytic Reduction of NOx with ammonia was described. Its surface composition was identified. It was found that on the surface of the most active catalysts there were V2Os, VO2, and V2O3. It was demonstrated that V4+ ions present on the surface were responsible for high effectiveness of the catalyst.
EN
Investigations of composites in GaN/TiN system may help in understanding complex phenomena observed at GaN/titanium metal interfaces as well as expand potential areas of their applications in modern electronics. In this report, we briefly describe the preparation of nanopowder composites of gallium nitride and titanium nitride, GaN/TiN, by two distinct synthetic methods: aerosol-assisted vapor phase synthesis (AAVS) and anaerobic precursor route. The products were characterized by spectroscopic and microscopic methods. Herein, discussed are mainly studies by X-ray photoelectron spectroscopy, XPS.
EN
Surface changes in naturally occurring metal sulphides (pyrite, arsenopyrite, sphalerite, chalcopyrite, galena and molybdenite) due to the treatments from high – power electromagnetic pulses (HPEMP) at varying times were studied using XPS. Analysis of the obtained results revealed common patterns and differences in surface transformations. The transformations were found to include two main stages. The first stage were observed at low treatment intensities (up to N ~ 103 pulses). At this stage formation and accumulation in the surface layer of the nonstoichiometric sulphide phase, oxides and hydroxides, as well as elemental (polysulfide) sulphur and / or metastable sulphur species (thiosulfate, sulphite) were observed. The second stage (N ≥ 3 · 103 pulses) is characterized by the removal of sulphur species and renewal of the mineral surface (sulfidization). The application of HPEMP treatment to improve flotation selectivity is supported by single-mineral flotation tests. Changes in floatability as a result of HPEMP treatment are principally explained by surface phase changes.
PL
Zmiany powierzchni w naturalnie występujących siarczkach metali (piryt, arsenopiryt, sfaleryt, chalkopiryt, galena i molibdenit) w wyniku obróbki impulsami elektromagnetycznymi o dużej mocy (HPEMP) w różnym czasie badano przy użyciu XPS. Analiza uzyskanych wyników ujawniła typowe wzory i różnice w transformacjach powierzchniowych. Stwierdzono, że transformacje obejmują dwa główne etapy. Pierwszy etap obserwowano przy niskiej intensywności działania impulsami (do N ~ 103 impulsów). Na tym etapie zaobserwowano tworzenie i akumulację w warstwie powierzchniowej niestechiometrycznej fazy siarczkowej, tlenków i wodorotlenków, a także siarki elementarnej (polisiarczkowej) i / lub metastabilnej (tiosiarczan, siarczyn). Drugi etap (N ≥ 3 · 103 impulsów) charakteryzuje się usuwaniem rodzajów siarki i odnawianiem powierzchni mineralnej (siarczkowanie). Zastosowanie obróbki HPEMP w celu poprawy selektywności flotacji jest poparte testami flotacji pojedynczych minerałów. Zmiany flotowalności w wyniku obróbki HPEMP są wyjaśnione zmianami fazy powierzchniowej.
PL
Artykuł jest kontynuacją pracy opisującej wyniki badań XPS stali martenzytycznej 4H13 po standardowym elektrochemicznym polerowaniu bez mieszania [1]. Autorzy prezentują skład chemiczny warstwy wierzchniej po polerowaniu elektrochemicznym w polu magnetycznym. Wykonane badania uwidoczniają różnice warstw wierzchnich otrzymanych standardową metodą elektrochemicznego polerowania oraz metodą magnetoelektropolerowania.
EN
The article is a continuation of the work covering the XPS results of 4H13 martensitic steel after electrochemical polishing without mixing [1]. The authors present the chemical composition of the surface layer after electrochemical polishing in a magnetic field. The results show comparison of surface layers obtained by standard electrochemical polishing and magnetoelectropolishing.
6
75%
EN
Purpose: The aim of the work was to determine the surfaces as well as physicochemical properties changes of the metallic urological stent. The tested stent was made of Co-Cr-Ni-Fe-Mo-Mn alloy and was implanted during four years. Design/methodology/approach: Electrochemical tests have been used for corrosion resistance investigations. They were carried out in the artificial urine solution at the temperature 37 ± 1° C with the use of the VoltaLab ® PGP 201 system. The evaluation of pitting corrosion was realized by recording of anodic polarization curves with the use of the potentiodynamic method. Chemical composition investigations of the surface have been carried out with the use of X-ray Photoelectron Spectroscopy (XPS). The topography of surfaces changes was observed in scanning electron microscope (SEM). Findings: Surface observations haven't showed the signs of pitting corrosion. No decrease of corrosion resistance for metallic material was stated. Furthermore in surface layer the presence of the organic compounds was observed. Practical implications: The time of four years of implantation didn't induce the significant changes in electrochemical properties of metallic material of the tested stent which was in contact with the natural environment of physiological fluids. Originality/value: The results obtained concern to investigations of the metallic material of the stent, which was implanted during the period of four years in human body that mean in natural environment of human tissues and physiological fluids.
EN
The influence of the particle size on the surface sensitivity in XPS analysis was investigated. Previous reports about such influence were qualitatively only. In this report there are given mathematical description of XPS sensitivity and quantitative results. It was found that influence due to nanometric size on XPS analysis can be noticeable for particles below 15 nm of diameter and increases dramatically with reduction of the size.
8
71%
EN
Well-ordered nano-carbon materials, like multi-wall carbon nanotubes, graphene oxide, graphene due to their unique physical and chemical properties, are candidates for promising applications. In this work thin multilayered graphene, single layer graphene oxide layers and highly oriented pyrolytic graphite (HOPG) surface were treated by RF activated N2 gas plasma at nominally room temperature. Negative bias in the 0–200 V range and treatment time of 10 min was applied. Surface chemical alterations were followed by X-ray photoelectron spectroscopy (XPS). The applied treatments resulted in a significant build-up of nitrogen in the surface of these nano-carbon materials. The amount of nitrogen varied between 4 and 10 atomic %, depending on type of carbon and on biasing conditions. Evaluating the high-resolution N1s XP spectral region, typically three different chemical bonding states of the nitrogen were delineated. Peak component at 398.3 eV is assigned to C=N–C type, at 399.7 eV to sp2 N in melamine-type ring structure and at 400.9 eV to N substituting carbon in a graphite-like environment. Identical chemical bonding of the nitrogen was detected on the surface of HOPG treated in the same way for comparison.
9
Content available remote Colossal dielectric constant of NaNbO3 doped BaTiO3 ceramics
71%
EN
BaTiO3 ceramics doped with 0.40 mol% NaNbO3 were prepared using a traditional approach by sintering at temperature of 1250 ºC to 1290 ºC. The prepared ceramics was characterized by very good dielectric properties, such as high dielectric constant (1.5 × 105), low dielectric loss (0.1), and good dielectric temperature stability in the −40 ºC to 100 ºC range for the sample sintered below 1270 ºC. The dielectric characteristics obtained with XPS confirmed that Ti4+ ions remain in the state without any change. The huge increase in dielectric constant in NaNbO3 doped BaTiO3 samples occurs when large amount of Ba2+ ions are excited to a high energy bound state of Ba2+ − e or Ba+ to create electron hopping conduction. For samples with the content of NaNbO3 higher than 0.40 mol%, or sintering temperature higher than 1280 ºC, compensation effect is dominated by cation vacancies with sharply decreasing dielectric constant and increased dielectric loss. The polaron effect is used to explain the relevant mechanism of giant dielectric constant appearing in the ferroelectric phase.
EN
The paper presents the results of examinations of the structure and properties of Al2O3 + Ni3Al + Ni(Cr, Fe, Al) + Cr-Ni + Cr7C3 multilayers produced on nickel alloys by the plasma assisted chemical vapour deposition method with the participation of trimethylaluminum vapours in gaseous atmosphere. The layers have a high surface hardness of about 1200HV0.05, and high heat and frictional wear resistance. In order to find a correlation between the structure of the multilayers and their properties, the following examinations have been executed: phase analysis by XRD and surface analysis by XPS, analysis of microstructure by optical and scanning electron microscopes as well as X-ray microanalyser, micro-hardness measurements, corrosion and frictional wear resistance testing.
11
Content available remote Depth Analysis of Crystalline Silicon Used for Radiation-Hard Detectors
71%
EN
Depth analysis of metal-doped crystalline silicon by the X-ray photoelectron spectroscopy technique is presented in this work. The results from this technique are used to complement those from previous techniques. The metals diffused into the silicon are gold, platinum, erbium, and niobium. In silicon, these metals induce defects that are responsible for relaxation behaviour of the material. Relaxation material is radiation-hard since the effects of radiation on devices fabricated on the material are suppressed. Considerable amounts of gold, platinum, and niobium are found in the silicon bulk. The results of this work are in good agreement with those reported earlier on the same samples using the Rutherford backscattering technique. The spectra of the natural contaminants, carbon and oxygen, are also analysed in this work.
12
Content available remote Enhancement of XPS surface sensitivity in nanocrystalline material
71%
EN
The influence of the particle size on the surface sensitivity in XPS analysis was investigated. Previous reports about such influence were qualitatively only. In this report there are given mathematical description of XPS sensitivity and quantitative results. It was found that influence due to nanometric size on XPS analysis can be noticeable for particles below 15 nm of diameter and increases dramatically with reduction of the size.
EN
The main purpose of this study was to investigate the segregation and oxidation of phosphorus on the polycrystalline iron surface using the AES and XPS methods. The segregation of phosphorus begins at 600 K and the maximum concentration of phosphorus on the surface is achieved at 720 K, as in the case of a monocrystalline sample. The segregation of sulphur begins above 720 K, whereas the phosphorus surface concentration decreases. The oxidation of the iron surface covered with phosphorus results in the formation of both the oxygen-phosphorus bonds and the oxygen-iron bonds. The different forms of surface species have been proposed.
14
Content available remote XPS Study of group IA carbonates
71%
EN
The results of systematic XPS measurements of all alkali metal carbonates (Li, Na, K, Rb and Cs) are presented. The first set of experiments was performed with “as received” commercial carbonate powders under liquid nitrogen conditions using a precooling procedure. A second set of experiments was performed under similar experimental conditions after a preliminary grinding (mechanical activation) of the carbonates. In addition, Na2CO3 *1H2O, NaHCO3 and KHCO3 powders were studied. It was found that sample pre-cooling allows distinction between hydrocarbonates and carbonate hydrates. Storage in air leads to formation of hydrocarbonates at the surface of Li2CO3 and Na2CO3. This phenomenon being more pronounced in the former. In contrast, K2CO3 forms a hydrate with one H2O molecule. Rb2CO3 and Cs2CO3 have hydrocarbonates as well as hydrates at the surface and this is more pronounced for Cs2CO3. Grinding of the carbonates results in the formation of hydrocarbonates at the surface, the tendency to do so was found to increase down the group IA, namely, K
EN
The paper presents the problem of utilization of extruded polystyrene wastes by its secondary use as filler for cement composites. Wastes were obtained from a company carrying out thermomodernisation works in the form of shapeless, undersized construction waste. The remains of the boards were crushed and separated using the sieve method. The basic technical parameters of thus prepared waste were assessed in terms of its use as a lightweight aggregate for concrete. The technical properties of wastes were compared with those of traditional aggregates used in concrete composites. During the research work, the samples of a cement composite were produced in which the waste served as a filler. In successive test series, the waste constituted 30, 50 and 100% of the aggregate substitution in the mix. Comparative samples without waste were also made. The results showed that the waste could potentially be used to produce lightweight cement composites with high strength parameters.
16
Content available remote Electronic properties of CeNi4Si compound
71%
EN
Temperature dependence of the specific heat for CeNi4Si was analyzed. These studies were supported by magnetic susceptibility, electrical resistivity and X-ray photoemission spectroscopy measurements.CeNi4Si is paramagnetic and follows the Curie-Weiss. This effective paramagnetic moment is lower than that for the free Ce3+. The f-occupancy nf and coupling between the f level and the conduction state are derived to be about 0.91 and 36 meV, respectively. Both the susceptibility data and the XPS spectra have shown that Ce ions are in intermediate valence state. The specific heat has been analyzed considering the electronic contribution, the Schottky anomaly, and the lattice contributions within the Debye model. The scheme of the energy levels created by the crystal electric field split is determined from the Schottky contribution to the specific heat.
17
Content available remote Electronic structure of CeRh2Sn4
71%
EN
We performed a study of the compound CeRh2Sn4, not investigated so far. Our samples were carefully characterized by X-ray powder diffraction analysis and by locally resolved, energy dispersive X-ray spectroscopy (EDXS). We present a combined experimental and theoretical study based on X-ray photoelectron spectroscopy (XPS) data together with ab initio band structure calculations. The Ce 3d XPS spectrum indicates a small mixed valence of Ce. Analysis of the 3d94f 2 weight using the Gunnarsson-Schönhammer theory suggests a hybridization between Ce 4f states and the conduction band of about 85 meV. The valence band spectrum, dominated by Rh 4d states, is in a very good agreement with the calculated one.
PL
W artykule przedstawiono skład chemiczny warstwy powierzchniowej i objętościowej wełny szklanej i skalnej. Analizy zostały przeprowadzone przy użyciu dwóch metod instrumentalnych (nieinwazyjnych technik), rentgenowskiej analizy fluorescencyjnej (XRF, X-Ray Fluorescence) i rentgenowskiej spektrometrii fotoelektronów (XPS, X-Ray Photoelectron Spectroscopy). Zaobserwowano, że skład wełny szklanej i skalnej jest zróżnicowany. Charakteryzuje się on zawartością głównych tlenków, takich jak SiO2, Al2O3, CaO, MgO oraz Fe2O3. Analizowane wełny mineralne są materiałami o złożonym składzie chemicznym, a użyte metody spektroskopowe w dobrym stopniu odzwierciedlają ich główne składniki. Wykazano przewagę rentgenowskiej analizy fluorescencyjnej (XRF) nad metodą XPS, oraz ich wzajemną komplementarność.
EN
Chemical composition of glass wool and stone wool has been investigated. Researches were carried out by using two analytical techniques, X-ray fluorescence analysis (XRF) and X-ray photoelectron spectroscopy (XPS). The both methods are non-destructive. It was observed that composition of the glass wool and stone wool is variable, but it characterizes by the content of the main oxides as SiO2, Al2O3, CaO, MgO, and Fe2O3. Analyzed wool samples are materials having complex chemical composition, and used spectroscopic methods in good extent reflect their main ingredients. It has been demonstrated the advantage of XRF method over the use of XPS technique, and their mutual complementarity.
EN
Cr-free conversion coatings were deposited from a bath containing: titanium(III) chloride, fluorosilicic acid, hydrogen peroxide and oxalic acid. An XPS analysis of the coating deposited for 3 min showed titanium to be present mainly at the +4 oxidation state number and zinc at the +2 oxidation state number, in the form of oxides and hydroxides. Silicon forms silicates. DC polarization showed that the corrosion current densities for the coatings deposited for 30 s – 6 min were below 1 μA·cm−2 and lower than that of zinc coating. EIS and neutral salt spray test revealed that in order to ensure good protective properties deposition should be conducted for at least 3 minutes.
PL
Bezchromowe powłoki konwersyjne otrzymano z kąpieli zawierającej: chlorek tytanu(III), kwas fluorokrzemowy, nadtlenek wodoru oraz kwas szczawiowy. Analiza XPS powłoki osadzanej przez 3 minuty wykazała obecność tytanu na +4 stopniu utlenienia oraz cynku w formie utlenionej, zarówno pod postacią tlenków jak i wodorotlenków. Na podstawie pomiarów polaryzacyjnych stałoprądowych obliczono szybkość korozji w 0.5 M NaCl powłok osadzanych w zakresie 30 s do 6 min, która była niższa od 1 μA·cm−2 oraz niższa od szybkości korozji porównawczej powłoki cynkowej. Badania zmiennoprądowe metodą EIS oraz test w komorze solnej pozwoliły stwierdzić, że dobre właściwości ochronne posiadają powłoki bezchromowe osadzane przez przynajmniej 3 minuty.
PL
Celem badań było określenie wpływu domieszek metali szlachetnych (Pt, Au) na strukturę i parametry warstwy gazoczułej opartej na WO₃ rezystancyjnych czujników gazów. Analiza widm uzyskanych z wykorzystaniem XPS potwierdziła skład warstw. Dodatek metali szlachetnych zarówno w ilości 3,2%, jak i 6,5% nie wpłynął na położenie i kształt pików odpowiadającym orbitalom charakterystycznym dla W, Pt i Au. Jednakże, dokładna analiza widm orbitalu O1s wykazała, że domieszka złota znacząco wpłynęła na ilość zaadsorbowanych na powierzchni cząsteczek wody.
EN
The aim of the research was to determine the influence of noble metal dopants (Pt, Au) on the structure and parameters of the sensitive gas layer of resistive gas sensors. The analysis of XPS spectra confirmed the composition of layers. The addition of noble metals into sensitive gas layer do not have influence on the position and shape of the peaks corresponding to the orbitals characteristic for W, Pt and Au. However, analysis of O1s spectra clearly revealed that gold dopant significantly influenced on the amount of adsorbed water on the surface.
first rewind previous Strona / 6 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.