S. Jørgensen

NITROGEN FUNCTIONALITY DISTRIBUTIONS IN ASPHALTENES ISOLATED FROM SEVERAL OILS FROM DIFFERENT SOURCE ROCK TYPES

Abstract Seven asphaltenes isolated from oils from different source rock types have been examined by X-ray photoelectron spectroscopy (XPS) to determine their gross nitrogen speciation. Five-membered ring pyrrolic nitrogen and six-membered ring pyridinic nitrogen species are the main types present, with pyrrolic nitrogen dominating in all samples. Pyrrolic nitrogen:pyridinic nitrogen ratios were in the range of 1.44–4.26.

Segregation of Sr in Sr‐doped LaPO4 ceramics

Lanthanum phosphate (LaPO4) powders with 1, 2 and 5 mol.% Sr substitution were prepared and sintered at 1450 °C. Bulk, grain boundaries and surfaces of different origins were investigated using powder x-ray diffraction (XRD), SEM, electron probe microanalysis (EPMA), transmission electron microscopy (TEM) and XPS in order to determine the bulk solubility of Sr and extent of segregation and precipitation. A secondary phase (Sr3La(PO4)3) distributed in matrix was found by powder XRD, SEM and EPMA in the 2% and 5% samples. The EPMA indicates that the bulk solubility of Sr is ∼1%. A crystalline secondary phase (possibly Sr2P2O7) at the triple points and some Sr enrichment at the grain boundaries were found by TEM in the 2% and 5% samples. The XPS taken with Mg anode x-rays on different surfaces showed Sr enrichment in thermally annealed surfaces, as well as in intergranular fractures. Features in XPS spectra of these fractures and surfaces support the presence of a thin La-free or La-poor film of a few atomic layers. Ion etching removed the Sr-rich layers in both cases. Copyright

A study of the alloying behaviour of Ni–B amorphous catalysts using Auger parameter measurements, and primary and secondary features of the XPS spectrum

Electrodeposited Ni–B alloys of nominal compositions 30 at.% B and 50 at.% B, which were developed as catalysts for the electrolytic hydrogen production process, were studied using X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The Ni–B alloys were found to be amorphous. Changes of Auger parameter (AP) values and information from the primary and secondary structure of the XPS spectrum were employed to probe the electronic changes occurring upon alloying. It is suggested that the main electronic change occurring is hybridisation of the Ni occupied states with the B sp empty states and an apparent increase of the electron density around the Ni sites. The electron affinities of the two elements contradict their electronegativity tendencies. It is suggested that the contradiction may be resolved by considering the increase in the electron density at the Ni sites in the Ni–B alloys to be a result of shortening of the interatomic distances via the formation of hybridized bonds between Ni and B atoms.

A Study of Anodically Grown Hydroxide Films on an Amorphous Ni78Si8B14 Alloy

Films grown on amorphous Ni 75 si 8 B 14 alloy and on polycrystalline Ni by polarization in 1 M KOH solution were analyzed by X-ray photoelectron spectroscopy (XPS) and scanning tunneling spectroscopy (STS). XPS investigations showed that the films formed on both the amorphous Ni 78 Si 8 B 14 alloy and polycrystalline Ni at open-circuit potential and after polarization at 0.4 V RHE consist of Ni(OH) 2 , while the films formed after polarization at 0.5 V RHE consist of NiOOH. No traces of B or Si in the uppermost of the hydroxide films produced on the amorphous Ni 78 Si 8 B 14 alloy were found. STS showed that all films formed on the amorphous Ni 78 Si 8 B 14 had more n-type semiconductor character than those formed on polycrystalline Ni. Electrochemical investigations indicated that the amorphous Ni 78 Si 8 B 14 alloy is a better electrocatalyst for the oxygen evolution reaction than polycrystalline Ni. We discuss whether this can be attributed to an enhanced electron density on the Ni sites in the alloy leading to an increase in the tunneling probability of the electrons on the surface film. This can subsequently enhance its catalytic action towards the oxygen evolution reaction.

Formation of Nano-Structures on ITO Antireflection Coating by Hydrogen Plasma Treatments

Recently, low dimensional semiconductor structures such as metallic nanoparticles, have attracted significant attention for photovoltaics. In this work we study the low-temperature formation of metallic nano-dots in an indium tin oxide (ITO) antireflection coating for solar cells after an appropriate hydrogen plasma treatment. Atomic force microscopy (AFM), scanning spreading resistance microscopy (SSRM), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were used for the analysis of the morphology, electrical properties and composition of ITO layers deposited on Corning glass at different temperatures and subsequently subjected to hydrogen plasma. Formation of highly conductive nano-structures at hydrogenation temperatures below 250degC is observed. It is shown that the nano-structures formation can be controlled by the time and the temperature of the hydrogenation

A STUDY ON THE PRECIPITATION OF Ge-RICH NANOPARTICLES IN A LUMINESCENT (Er, Ge) CO-DOPED SiO2 FILM SPUTTERED WITH Ar + O2 PLASMA

We report the photoluminescence (PL) from an (Er, Ge) co-doped SiO2 film deposited by rf-magnetron sputtering in an Ar + O2 ambience. The sample film was annealed in N2 for 30 min at different temperatures. The PL intensity increases as the annealing temperature increases from 700 to 1000°C, and drops to very weak after 1100°C annealing. High-resolution transmission electron microscopy (TEM) observation shows that there are some Ge-rich nanoparticles precipitated after 700°C annealing, and more clusters precipitated after 1000°C annealing. However, no Ge nanocrystals were found in these films, the diffraction patterns are always halo which indicates that the precipitated clusters are in amorphous states. X-ray photoelectron spectroscopy (XPS) analysis indicates the Ge in the nanoclusters is mostly in an oxidized state and the oxidation state of Er increases with increasing annealing temperature.