Vacuum annealing phenomena in ultrathin TiDy/Pd bi-layer films evaporated on Si(100) as studied by TEM and XPS

Using a combination of TEM and XPS, we made an analysis of the complex high-temperature annealing effect on ultrathin titanium deuteride (TiDy) films evaporated on a Si(100) substrate and covered by an ultrathin palladium layer. Both the preparation and annealing of the TiDy/Pd bi-layer films were performed in situ under UHV conditions. It was found that the surface and bulk morphology of the bi-layer film as well as that of the Si substrate material undergo a microstructural and chemical conversion after annealing and annealing-induced deuterium evolution from the TiDy phase. Energy-filtered TEM (EFTEM) mapping of cross-section images and argon ion sputter depth profiling XPS analysis revealed both a broad intermixing between the Ti and Pd layers and an extensive inter-diffusion of Si from the substrate into the film bulk area. Segregation of Ti at the Pd top layer surface was found to occur by means of angle-resolved XPS (ARXPS) and the EFTEM analyses. Selected area diffraction (SAD) and XPS provided evidence for the formation of a new PdTi2 bimetallic phase within the top region of the annealed film. Moreover, these techniques allowed to detect the initial stages of TiSi phase formation within the film–substrate interlayer

The identification of Jewish patterns of food preparation and consumption: a zooarchaeological approach to the Medieval and early Modern evidence from Central-Eastern Europe

The thesis addresses the question of detecting traces of Jewish presence in the zooarchaeological record. It discusses the cultural aspects of meat provisioning adopted by the medieval and early modern Jewish communities in Polish and Czech lands. Two indicators of Jewish presence in zooarchaeology are discussed: the presence/absence of the bones of non-kosher animals (especially pig) and the hindlimbs of cattle and caprine. The evidence suggests that both indicators can successfully contribute to detecting the Jewish footprint in animal bone assemblages. However, they are not as straightforward as previously thought, and need to be supplemented with other lines of evidence, as well as interpreted in their broader archaeological and historical contexts. Most crucial is a thorough analysis of the religious, historical, and ethnographic aspects of porging practice—a butchery activity essential for producing kosher meat—and its detection on bones. The study presented here reveals the occurrence of porging on bones from the Middle Ages and early modern period, and discusses their possible uses. Further zooarchaeological analyses show regional and temporal differences in Jewish meat provisioning and consumption connected to wealth and possibly local traditions. The thesis also discusses the issue of observance and transgression of the dietary rules in the Middle Ages and early modern period and their impact on Jewish identity, as demonstrated through zooarchaeological analysis

Structural and chemical evolution of single-wall carbon nanotubes under atomic and molecular deuterium interaction

The interaction of atomic (D) and molecular (D2) deuterium, as present in a (D + D2) gas mixture, with single-wall carbon nanotubes (SWNTs) has been studied by means of a combination of scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The SWNT samples were exposed to the gas mixture, produced by thermal dissociation of D2 on a hot W filament, its temperature, TW, being kept at 1020 and 1550 K for a deuterium pressure of 0.6 and 60 Pa, respectively. Prolonged interaction of the low-pressure (D + D2) gas mixture produced at TW = 1020 K leads to a conglomeration of the SWNT bundles into larger diameter ropes of square and triangular cross-section, covered by nano-aggregates of graphite material. Both the coalescence of single SWNTs and a massive reconstruction of bundles of SWNTs into a “coral reef”-like structure were found to occur after prolonged exposure of SWNTs to the high-pressure (D + D2) gas mixture produced at TW = 1550 K. This structure is formed by the encapsulated Fe nanoparticles and deuterocarbon-like species appearing as a result of the deuterium interaction with the SWNT bundles accompanied by partial erosion of the SWNT material. The XPS valence-band spectra disclose electronic features characteristic for a hydrogen-plasma modified multi-wall carbon nanotube (MWNT)-like structure as a result of an intensive (D + D2) induced transformation of the SWNTs into the “coral reef”-like structure

Interaction between plasma sprayed YBaCuO and nimonic substrates

The interaction of YBaCuO layers, deposited by atmospheric plasma spraying, with nimonic substrates at high temperature has been studied using X-ray photoelectron spectroscopy and Auger electron spectroscopy (AES). Both the region at the YBaCuO/ nimonic interface and the surface of clean nimonic substrates after annealing in vacuum and oxygen have been studied in terms of chemical composition and peak shapes. Chromium was detected more than 20 ¿m deep in the YBaCuO layer. This is explained in terms of a chemical reaction of Cr3+ oxides from the nimonic with the YBaCuO. Depth profiling of the interface region combined with AES measurements reveals also an extensive migration of nickel oxides from the substrate into the YBaCuO

Microstructural and chemical transformation of thin Ti/Pd and TiDy/Pd bi-later films induced by vacuum annealing

Using a combination of scanning electron microscopy, transmission electron microscopy (TEM), X-ray diffraction and X-ray photoelectron spectroscopy (XPS), we made a comparative study of the high-temperature annealing impact on thin titanium deuteride (TiD y ) films covered by an ultrathin Pd layer, and on Ti/Pd bilayer films. The bilayer films were prepared under ultrahigh vacuum conditions and were in situ annealed using the same annealing procedure. It was found that the surface and the bulk morphology of both films undergo different annealing-induced transformations, leading to an extensive intermixing between the Ti and Pd layers and the formation of a new PdTi2 bimetallic phase. Energy-filtered TEM imaging and energy-dispersive X-ray spectrometry analysis, as well as XPS depth profiling all provided evidence of a different distribution of Pd and Ti in the annealed TiD y /Pd film compared with the annealed Ti/Pd film. Our results show that thermal decomposition of TiD y , as a consequence of annealing the TiD y /Pd film, modifies the intermixing process, thereby promoting Ti diffusion into the Pd-rich top layer of the TiD y film and thus providing a more likely path for the formation of the PdTi2 phase than in an annealed Ti/Pd fil

Gold catalysts supported on ceria doped by rare earth metals for water gas shift reaction: Influence of the preparation method

Cataloged from PDF version of article.Gold catalysts based on ceria, doped by various RE metals (La, Sm, Gd, Yb, Y) were studied. The influence of the preparation methods on structure, properties and catalytic activity in the WGS reaction was investigated. The catalysts' supports were prepared using two different methods: co-precipitation (CP) and mechanochemical activation (MA). The catalysts were tested in a wide temperature interval without and after reactivation. All samples were characterized using a combination of X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), Raman spectroscopy (RS) and X-ray photoelectron spectroscopy (XPS) and TPR. It was found that the catalytic activity of MA catalysts is higher than CP ones. The gold catalysts based on ceria doped by Yb and Sm exhibited the highest activity. After reactivation in air the MA samples almost kept the WGS activity same, while the CP catalysts increased it. The catalysts of a single- and double-phase structure are formed as a result of CP and MA preparation, respectively. There are no big differences in the gold particles size (2-3 nm) depending on dopants and on the preparation techniques. The RS spectra analysis indicates that most probably the oxygen vacancies are adjacent to Me(3+) dopant and the ceria structure seems to be better ordered than in the case of alumina as a dopant. There is no distinct correlation between reducibility and WGS activity. The XPS analysis disclose positively charged gold particles in addition to metallic gold within a surface region of fresh samples and only metallic gold on the samples after catalytic processing. There is no simple correlation between the concentration of Ce(3+) in the samples and their WGS activity. (C) 2009 Elsevier B.V. All rights reserved

Spin measurements for 147Sm+n resonances: Further evidence for non-statistical effects

We have determined the spins J of resonances in the 147Sm(n,gamma) reaction by measuring multiplicities of gamma-ray cascades following neutron capture. Using this technique, we were able to determine J values for all but 14 of the 140 known resonances below En = 1 keV, including 41 firm J assignments for resonances whose spins previously were either unknown or tentative. These new spin assignments, together with previously determined resonance parameters, allowed us to extract separate level spacings and neutron strength functions for J = 3 and 4 resonances. Furthermore, several statistical test of the data indicate that very few resonances of either spin have been missed below En = 700eV. Because a non-statistical effect recently was reported near En = 350 eV from an analysis of 147Sm(n,alpha) data, we divided the data into two regions; 0 < En < 350 eV and 350 < En < 700 eV. Using neutron widths from a previous measurement and published techniques for correcting for missed resonances and for testing whether data are consistent with a Porter-Thomas distribution, we found that the reduced-neutron-width distribution for resonances below 350 eV is consistent with the expected Porter-Thomas distribution. On the other hand, we found that reduced-neutron-width data in the 350 < En < 700 eV region are inconsistent with a Porter-Thomas distribution, but in good agreement with a chi-squared distribution having two or more degrees of freedom. We discuss possible explanations for these observed non-statistical effects and their possible relation to similar effects previously observed in other nuclides.Comment: 40 pages, 13 figures, accepted by Phys. Rev.

Fast-Neutron Activation of Long-Lived Isotopes in Enriched Ge

We measured the production of \nuc{57}{Co}, \nuc{54}{Mn}, \nuc{68}{Ge}, \nuc{65}{Zn}, and \nuc{60}{Co} in a sample of Ge enriched in isotope 76 due to high-energy neutron interactions. These isotopes, especially \nuc{68}{Ge}, are critical in understanding background in Ge detectors used for double-beta decay experiments. They are produced by cosmogenic-neutron interactions in the detectors while they reside on the Earth's surface. These production rates were measured at neutron energies of a few hundred MeV. We compared the measured production to that predicted by cross-section calculations based on CEM03.02. The cross section calculations over-predict our measurements by approximately a factor of three depending on isotope. We then use the measured cosmic-ray neutron flux, our measurements, and the CEM03.02 cross sections to predict the cosmogenic production rate of these isotopes. The uncertainty in extrapolating the cross section model to higher energies dominates the total uncertainty in the cosmogenic production rate.Comment: Revised after feedback and further work on extrapolating cross sections to higher energies in order to estimate cosmic production rates. Also a numerical error was found and fixed in the estimate of the Co-57 production rat