Resolution X-ray Photoelectron Spectroscopy Spectra Research Articles

Surface chemical characterization of nanoparticle coated paperboard

The chemical composition of nanoparticle coated paperboard surfaces was characterized. The deposition of SiO2 and TiO2 nanoparticles induced changes in wetting properties of the paperboard surface: a superhydrophilic surface was created by SiO2 nanoparticles and a superhydrophobic surface by TiO2 nanoparticles. Both X-ray photoelectron spectroscopy (XPS) and contact angle (CA) measurements were used to study the surface properties of the samples. The low and high resolution XPS spectra were collected to evaluate the chemical composition before and after nanoparticle deposition. The SiO2 nanocoated sample has the highest values of both O to C and C2 to C1 ratios, which indicates a high relative amount of hydroxyl groups. On the other hand, carbon C1 peak which represents the hydrocarbon type of bonds, is on higher level for TiO2 when compared to the SiO2 nanocoated sample. This may be related to the replacement of hydroxyl groups by aliphatic chains on the superhydrophobic surface of TiO2 nanoparticle coated sample.

Composition depth profiles of Bi 3.15Nd 0.85Ti 3O 12 thin films studied by X-ray photoelectron spectroscopy

In the present work, X-ray photoelectron spectroscopy (XPS) was used to investigate the composition depth profiles of Bi 3.15Nd 0.85Ti 3O 12 (BNT) ferroelectric thin film, which was prepared on Pt(1 1 1)/Ti/SiO 2/Si(1 0 0) substrates by chemical solution deposition (CSD). It is shown that there are three distinct regions formed in BNT film, which are surface layer, bulk film and interface layer. The surface of film is found to consist of one outermost Bi-rich region. High resolution spectra of the O 1 s peak in the surface can be decomposed into two components of metallic oxide oxygen and surface adsorbed oxygen. The distribution of component elements is nearly uniform within the bulk film. In the bulk film, high resolution XPS spectra of O 1 s, Bi 4 f, Nd 3 d, Ti 2 p are in agreement with the element chemical states of the BNT system. The interfacial layer is formed through the interdiffusion between the BNT film and Pt electrode. In addition, the Ar +-ion sputtering changes lots of Bi 3+ ions into Bi 0 due to weak Bi–O bond and high etching energy.

Investigations on the low voltage cathodoluminescence stability and surface chemical behaviour using Auger and X-ray photoelectron spectroscopy on LiSrBO 3:Sm 3+ phosphor

Orange-red emissive LiSrBO 3:Sm 3+ phosphors were synthesized through the solid-state reaction method. Under UV radiation (221 nm) and low-voltage electron beam (2 keV, 12 mA/cm 2) excitation, the Sm 3+ doped LiSrBO 3 phosphor shows emission corresponding to the characteristic 4G 5/2- 6H 7/2 transitions of Sm 3+ with the strongest emission at 601 nm. A high stability of cathodoluminescence (CL) emission during prolong electron bombardment with low-energy electrons was observed. Surface sensitive diagnostic tools such as Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) were used to study the surface chemistry. AES results revealed modifications in the surface concentrations of Li, Sr, B, O and C on the surface of the LiSrBO 3:Sm 3+ phosphor as indicated by the changes in their Auger peak to peak heights (APPH) as a function of electron dose. Observed changes in the high resolution XPS spectra of the LiSrBO 3:Sm 3+ surface irradiated with the low energy electron beam provide evidence of compositional and structural changes as a result of the electron beam stimulated surface chemical reactions (ESSCRs). Additional SrO 2 was identified by XPS on the phosphor surface after it received an electron dose of 300 C/cm 2 together with the increase in the concentrations of chemical species containing the B–C–O bonding. The new surface chemical species formed during electron beam bombardment are possibly responsible for the stability of the CL in the LiSrBO 3:Sm 3+ phosphor.

Phase evolution studies of sol–gel derived lead zirconate titanate (PZT) nanopowder using X-ray diffraction and X-ray photoelectron spectroscopy

We report here the formation of single phase lead zirconate titanate (PZT) nanopowder with composition Pb(Zr0.52Ti0.48)O3 and average crystallite size 12–20 nm, synthesized by sol–gel process. The phase evolution of PZT gel powder, heat treated at temperatures 550, 650 and 800°C was monitored by X-ray diffraction (XRD) and X-ray photo-electron spectroscopy (XPS). The high resolution XPS spectra of Pb4f, Zr3d, Ti2p and O1s show that PZT with pure perovskite structure is obtained at 800°C while at lower temperatures pyrochlore phase co-exists with perovskite phase. The XRD results also support this analysis. We have also identified the pyrochlore phase using XPS by analyzing the corresponding variations in the FWHM values, peak positions and the separation between the spin doublets of Pb, Zr and Ti associated with it. The composition of the final powder obtained with pure perovskite structure is calculated and is close to the designed value.

Synthesis–Structure–Property Relations in Layered, “Li-excess” Oxides Electrode Materials Li [ Li1 / 3 − 2x / 3NixMn2 / 3 − x / 3 ] O2 (x = 1 / 3 , 1/4, and 1/5)

Relations between synthesis conditions, detailed crystal structures, and electrochemical properties of the Li-excess layered oxides are studied by X-ray diffraction, scanning electron microscopy (EELS), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and electron energy-loss spectrometry, combined with electrochemical property measurements including potentiostatic intermittent titration technique (PITT). Optimal synthesis conditions are obtained for stoichiometric samples sintered at in air followed by furnace cooling. The materials exhibit capacities of , 230, and 200 mAh/g within a voltage range of 2–4.8 V on discharge for , 1/4 and 1/3, respectively. Diffraction data of electrochemically cycled electrode materials show an expanded lattice ratio and changing Li/Ni interlayer mixing indicating peculiar cation migration in the structures. High resolution TEM images and XPS spectra show obvious differences in the surface characteristics of the samples synthesized with stoichiometric and excess amount of LiOH, suggesting that surface characteristics is one of the contributing factors to the difference in electrochemical properties. Our results suggest that the first cycle irreversible capacity is affected by both the bulk and surface characteristics of pristine materials, which is strongly influenced by precursor chemistry. The PITT results suggest that cation rearrangement during the charge/discharge has a significant impact on the lithium chemical diffusivity.

Size-controllable synthesis of chromium oxyhydroxide nanomaterials using a soft chemical hydrothermal route

Chromium oxyhydroxide nanomaterials were synthesised through a simple soft chemical hydrothermal method. The chromium oxyhydroxide materials display platelet morphology with clear edges, ~11 nm in diameter. CrO(OH) nanomaterials synthesised under different conditions were fully characterised by X-ray diffraction (XRD), transmission electron microscopy (TEM) combined with selected area electron diffraction (SAED), scanning electron microscopy (SEM), BET specific surface area analysis, X-ray photoelectron spectroscopy (XPS) and thermal gravimetric analysis (TGA). Bonding of the trivalent chromium from the oxyhydroxide nanomaterials was defined through the analysis of their high resolution XPS spectra for Cr 2p3/2 and O 1s. The thermal stability of the nanomaterials CrO(OH) was established. This research has developed methodology for the synthesis of chromium oxyhydroxide nanoplates.

Study of natural aging of industrial low density polyethylene by X-ray photoelectron spectroscopy

X-ray photoelectron spectroscopy (XPS) was used to study the natural outside aging of industrial low density polyethylene (LDPE) under the influence of one year round weather. Two types of LDPE were studied. The first type was LDPE without additives and the second type was doped with 4% of hindered amine light stabilisers (HALS). Unstabilised and 4% HALS stabilised LDPE samples underwent an oxidation of the polymeric matrix, by the production of C–O, C=O and O=C–O groups. These chemical functions were observed in high resolution XPS spectra around C1s and O1s peaks. From these results, it was then possible to propose mechanisms of natural aging of LDPE in such conditions. On the other hand, there is no clear evidence that HALS could be effective in natural aging for the polymer surfaces with exposure to the elements.

XPS analysis of W xC y thin films prepared by sputter deposition

W x C y thin films with different compositions were studied in order to correlate their properties with the thin-film composition and chemical bonding of C and W atoms. Three W x C y thin films with C concentrations in the range 40–80 at% were deposited on WC–Co substrates by the plasma beam sputtering technique. The composition of the thin films and chemical states of elements were analysed by X-ray photoelectron spectroscopy (XPS) depth profiling. The C and W concentrations in the films were quantified using XPS intensities from a WC–Co substrate with a known composition. The C1s peaks in the high energy resolution XPS spectra of thin films allowed identification of the WC phase and the amorphous carbon phase as a function of the film composition. The results show that the amorphous carbon a-C phase is present in those films with composition x< y. The measured hardness of the films decreases with a decrease of the WC concentration.

High resolution X-ray photoelectron spectroscopy of beta gallium oxide films deposited by ultra high vacuum radio frequency magnetron sputtering

The gallium oxide thin films with amorphous, crystalline, and nanostructure morphologies were deposited by a radio frequency magnetron sputtering system in ultra high vacuum conditions. High resolution X-ray photoelectron spectroscopy spectra of films were analyzed relating on the preparation conditions. On the amorphous films, the density of states at valence band region is dependent on the sputtering gas compositions. Beta gallium oxide (100) films are epitaxially deposited on magnesium oxide (100) crystalline substrate. The high resolution X-ray photoelectron spectra suggest the presence of the density of states valence band region with oxygen deficiency out of the stoichiometry on the epitaxial crystalline beta gallium oxide films.

Transformation of Poly(dimethylsiloxane) into thin surface films of SiOx by UV/Ozone treatment. Part I: Factors affecting modification

UV/ozone treatment of poly(dimethylsiloxane) (PDMS) was used to produce thin surface films of SiO x . Films of PDMS were applied by spin-coating onto gold-coated silicon wafers having (100) orientation. Characterization of the UV/ozone system was performed to map the spatial distribution of intensities of UV radiation. This mapping was used to ensure reproducible modification of films and to aid in the understanding of modification as measured by advancing contact angle using deionized water and x-ray photoelectron spectroscopy (XPS). Rutherford backscattering spectroscopy (RBS) was used to measure thickness of the PDMS films. Treatment reduced the wetting angle, in some cases from a value greater than 100° to a value less than 5°. High resolution XPS spectra were used to study the nature of the modified PDMS film and its relationship to the characteristics of the unmodified PDMS. High resolution XPS spectra in the Si 2p region show that O–Si–C bonds in the siloxane, observed prior to treatment, are converted to SiO x , where x is between 1.6 and 2. Modified films also contain some oxidized carbon components. The time required to reduce the contact angle to a minimum value was greater for the thicker PDMS film samples. The effects of ozone alone (without UV) and UV radiation at 184.9 and 253.7 nm (without ozone) were also investigated. The results of UV/ozone treatment are compared to results achieved by means of plasma surface oxidation.

Plasma Cleaning of a Commercially Available Hydroxyapatite-Coated External Fixation Pin by the Radio Frequency Glow Discharge Technique

Abstract The surface chemistry of a commercially available hydroxyapatite (HA)-coated external fixation pin in its as-received state has been studied using X-ray photoelectron spectroscopy (XPS). The XPS investigations revealed that the HA coating on the pin was contaminated with silicon (organosilicone) and it exhibited sub-stoichiometric chemical composition (i.e., Ca/P∼0.9). A comparison of the high resolution XPS spectra of both the HA-coated pin and the inside of its protective elastomer cap revealed that silicon to be in the form of an organosilane transferred from the protective cap to the HA surface, thus contaminating the latter. A parallel plate radio frequency glow discharge plasma cleaning system was successfully employed for removing the surface contaminant (organosilicone) from the HA-coated pin. As confirmed by XPS, plasma cleaning for 15 min was sufficient for achieving complete removal of the silicon contaminant and exposing a clean HA layer with a stoichiometric Ca/P ratio of 1.7.

Comparison study of physical vapor-deposited and chemical vapor-deposited titanium nitride thin films using X-ray photoelectron spectroscopy

The chemical compositions of physical vapor-deposited (PVD) and chemical vapor-deposited (CVD) titanium nitride (TiN) thin films were investigated by X-ray photoelectron spectroscopy (XPS). The effect of a H2/N2 plasma treatment on the chemical composition of CVD TiN thin film was also evaluated. The wafers were air-exposed before the XPS analysis. XPS depth profiles show that the PVD TiN has a N/Ti ratio of 1:1 with a small amount of oxygen in the film (less than 5 at.%). Significant amounts (∼20 at.%, respectively) of carbon and oxygen were observed in the air-exposed CVD TiN thin film, which has a N/Ti ratio of 0.5:1. The H2/N2 plasma treatment greatly reduced the carbon content in the CVD TiN thin film (less than 10 at.%) and a N/Ti ratio of 1:1 was achieved. High resolution XPS spectra indicate that the oxygen in all three TiN thin films analyzed was chemically bonded to Ti. The C1s peak of the as-deposited CVD TiN thin film was resolved into two peaks with binding energies of 282.2 and 284.7 eV, corresponding to the chemical states of carbide and organic carbon. After the H2/N2 plasma treatment, most of the organic carbon was removed with the remaining carbon present mainly as carbide in the CVD TiN thin film.

An XPS investigation of the oxidation/corrosion of melt-spun Mg

The oxide films formed on the surfaces of melt-spun Mg exposed to air, immersed in distilled water or 3% NaCl solution saturated with Mg(OH) 2 have been investigated by X-ray photoelectron spectroscopy (XPS). High resolution XPS spectra revealed two distinct oxygen species on the surface films: one assigned to O 2− in MgO, the other to OH − in Mg(OH) 2. Depth profiling revealed that the two species had different depth distributions in the films. The oxide film formed in air comprised a contamination outer layer and a relatively thick (5–6 nm) predominantly MgO inner layer. The film formed in distilled water or 3% NaCl solution saturated with Mg(OH) 2 was mainly a mixture of Mg(OH) 2 and MgO. Mg(OH) 2 was predominant at the top layer and decreased gradually with depth while MgO exhibited the opposite behavior. The corrosion product formed in 3% NaCl solution was more hydrated and much thicker that the films formed in the other two conditions. Cl − ion was incorporated in the oxide film formed in 3% NaCl solution. There exists both partial and complete dissociation of adsorbed water when melt-spun pure Mg ribbons are immersed in distilled water or 3% NaCl solution saturated with Mg(OH) 2.

Combined apparatus for x-ray photoelectron spectroscopy and extended x-ray absorption fine structure method using synchrotron radiation

A combined apparatus for Synchrotron Radiation (SR) was designed and developed in order to analyze the structure and properties of the solid surface. Two kinds of analyses; x-ray photoelectron spectroscopy (XPS) and x-ray absorption spectroscopy (XAS), are available using a 180° hemispherical electrostatic analyzer and/or other detection systems. High resolution XPS spectra were achieved with high signal-to-background ratio over a wide electron energy range up to 2600 eV using a monochromatized x ray (2600 eV) from SR. XAS spectra were obtained in two modes of total electron yield and Auger electron yield. The two modes described are complementary.

The application of x-ray photo-electron spectroscopy to a study of interfacial composition in corrosion-induced paint de-adhesion

Interfacial surfaces generated by corrosion-induced de-adhesion of organic coatings on bare steel have been analyzed by X-ray photo-electron spectroscopy (XPS). XPS elemental analyses have been used to provide an initial overview of changes in composition relative to untested surfaces; high resolution XPS spectra have been used to provide more detailed, sometimes semi-quantitative, analyses of molecular functional group composition. The high resolution spectra of specimen surfaces have been compared with each other and with reference compounds qualitatively and, in more detail, by calculating difference spectra and binding energy differences. Curve resolution methods have been employed to estimate functional group compositions. Corrosion-induced de-adhesion is associated principally with cathodic corrosion reactions and reaction products, including hydroxide. Epoxy ester-based coating interfacial surfaces have been demonstrated to bear (in addition to undegraded resin) carboxylate moieties indicative of ester saponification. For model epoxy-urethane and epoxy-amine coatings, a substantial carbonate residue is deduced. This residue is attributed to degradation of urethane and urea moieties. In addition, the presence of polymer residues on the interfacial substrate surfaces is demonstrated. It is concluded that de-adhesion involves substantial cohesive failure of the coating resin in the interfacial region.