We present a study of the atomic and chemical structure of the surface of a fully strained, TiO2-terminated, ferroelectric BaTiO3 (BTO) (001) epitaxial film on a SrTiO3 substrate after controlled exposure to water. The epitaxial quality was checked by atomic force microscopy and X-ray diffraction. Quantitative low-energy electron diffraction compared with multiple scattering simulations was used to measure the structure of the first few atomic layers of BTO surface. The surface chemistry was investigated using high-resolution X-ray photoelectron spectroscopy. Finally, temperature-programmed desorption measured the desorption energies. We find that water undergoes mainly dissociative adsorption on the polarized BTO(001) surface. There are two competing sites for dissociative adsorption: oxygen vacancies and on-top Ti surface lattice atoms. The Ti on-top site is the dominant site for OH– chemisorption. One fifth of the surface Ti atoms bind to OH–. The concentration of surface oxygen vacancies acts mainly to favor initial physisorption. Before exposure to water, the outward pointing polarization in the BTO film is stabilized by atomic rumpling in the TiO2 termination layer. After exposure to water, the chemisorbed OH– species provide the screening, inverting the surface dipole layer and stabilizing the bulk polarization. Molecular adsorption is observed only for high water coverage.

Ferroelectric hafnia-based thin films are promising candidates for emerging high-density embedded nonvolatile memory technologies, thanks to their compatibility with silicon technology and the possibility of 3D integration. The electrode–ferroelectric interface and the crystallization annealing temperature may play an important role in such memory cells. The top interface in a TiN/Hf0.5Zr0.5O2/TiN metal–ferroelectric–metal stack annealed at different temperatures was investigated with X-ray photoelectron spectroscopy. The uniformity and continuity of the 2 nm TiN top electrode was verified by photoemission electron microscopy and conductive atomic force microscopy. Partial oxidation of the electrode at the interface is identified. Hf is reduced near the top interface due to oxygen scavenging by the top electrode. The oxygen vacancy (VO) profile showed a maximum at the top interface (0.71%) and a sharp decrease into the film, giving rise to an internal field. Annealing at higher temperatures did not affect the VO concentration at the top interface but causes the generation of additional VO in the film, leading to a decrease of the Schottky Barrier Height for electrons. The interface chemistry and n-type film doping are believed to be at the origin of several phenomena, including wake-up, imprint, and fatigue. Our results give insights into the physical chemistry of the top interface with the accumulation of defective charges acting as electronic traps, causing a local imprint effect. This may explain the wake-up behavior as well and also can be a possible reason of the weaker endurance observed in these systems when increasing the annealing temperature.

A detailed investigation concerning the atomic structure of Cr 2 O 3 and Pd/Cr 2 O 3 ultrathin films deposited on a Ag(111) single crystal is presented. The films were prepared by MBE (molecular beam epitaxy) and characterized in situ by LEED (low energy electron diffraction), XPS (X-ray photoelectron spectroscopy), and XPD (X-ray photoelectron diffraction). Evidences of rotated domains and an oxygen-terminated Cr 2 O 3 /Ag(111) surface were observed, along with significant contractions of the oxide's outermost interlayer distances. The deposition of Pd atoms on the Cr 2 O 3 surface formed a four-monolayer film, fcc packed and oriented in the [111] direction, which presented changes in monolayer spacing and lateral atomic distance compared to the expected values for bulk Pd. The observed surface structure may shed light on new physical properties such as the induced magnetic ordering in Pd atoms.

We present X-ray photoelectron spectroscopy (XPS) and X-ray photoelectron diffraction (XPD) investigations of ordered chromium oxide ultrathin films prepared on a Pd(111) single-crystal surface.

The atomic surface structure of SrTiO 3 ͑100͒ after annealing at 630°C in vacuum is investigated by x-ray photoelectron diffraction ͑XPD͒ using the Sr 3d 5/2 core level. The photoelectron diffraction peaks are successfully assigned by considering the forward scattering of photoelectrons by the atomic potential near the emitter atom in the lattice. The strongest diffraction peaks are aligned along the single crystal internuclear axes. We compare the results of photoelectron multiple scattering calculations ͑MSC͒ of SrO and TiO 2 terminated SrTiO 3 ͑100͒ surfaces, including surface relaxation and rumpling, with the experimental data. For TiO 2 and SrO terminated SrTiO 3 ͑100͒ surfaces, all top-layer cations relax inward, whereas second-layer atoms relax outward. The surface rumpling for SrO-and TiO 2-terminated surfaces agrees well with low-energy electron diffraction results. Using a genetic algorithm the best agreement of MSC to the experimental XPD data is obtained for a SrO terminated surface with a 30% coverage of 3 ML SrO͑100͒ islands.

A detailed investigation concerning the surface atomic structure of the Au/Cr 2 O 3 model catalyst deposited on a Pd(111) single crystal surface is presented. The system was prepared by molecular beam epitaxy (MBE) and characterized in situ by low-energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS) and X-ray photoelectron diffraction (XPD). The element-specific short-range order information was obtained from XPD experiments supported by a comprehensive multiple scattering calculation diffraction approach. Based on the experiments, we have strong evidence of Au island formation on the Cr 2 O 3 surface.The experiments indicated that the islands are constructed of two Au monolayers and formed by the important structural relaxations in the three outermost atomic layers of the Au/Cr 2 O 3 surface. Such a surface structure could explain the particular catalytic reactivity displayed by catalysts based on Au nanoparticles dispersed on several oxide matrices.

The purpose of this study was to establish the biochemical parameters of the abaxial wall, dorsal wall and sole of the hoof of the medial thoracic, lateral, and medial pelvic digits of buffalos. The hoof samples were subjected to destructive biochemical analyses to identify the dry material (DM), mineral matter (MM), organic matter (OM), crude protein (CP) and ether extract (EE) contents. Sulfur (S), calcium (Ca), potassium (K), phosphorus (P), zinc (Zn) and copper (Cu) levels were determined based on nondestructive biochemical analyses. The parameters of dry material, mineral matter, organic matter, crude protein and ether extract of hoof capsule of the digits of buffalos can be determined by means of both destructive and nondestructive biochemical analysis. In addition, this study revealed that the highest concentrations of DM, CP and minerals such as, K, Zn and Cu are concentrated in the digits that bear the greatest body mass weight, suggesting that there is a positive correlation between the aforementioned parameters and the strength and growth of the hoof capsule in the digits. As for the element S, this study demonstrated that its highest concentration is located in the lateral digits of the pelvic members.Keywords: buffaloes, keratinized epidermis, minerals, crude protein RESUMO O presente estudo objetivou estabelecer os parâmetros bioquímicos da muralha abaxial, muralha dorsal e sola do casco dos dígitos torácico medial e pélvico lateral dos bubalinos. Foram realizadas analises bioquímicas destrutivas das amostras dos cascos para se obterem os teores de matéria seca (MS), matéria mineral (MM), matéria orgânica (MO), proteína bruta (PB) e extrato etéreo (EE). As análises bioquímicas não destrutivas foram empregadas para se avaliarem os níveis de enxofre (S), cálcio (Ca), potássio (K), fósforo (P), zinco (Zn) e cobre (Cu

The surface of a ferroelectric BaTiO 3 (001) single crystal was studied using synchrotron radiation induced x-ray photoelectron diffraction (XPD), x-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and low-energy electron diffraction (LEED). AFM, XPS, and LEED show that the surface is BaO terminated with a (1×1) reconstruction. The Ba 4d, Ti 2p, and O 1s XPD results were compared with multiple scattering simulations for out-of-(P + ,P − ) and in-plane (P in ) polarizations using a genetic algorithm to determine atomic rumpling and interlayer relaxation. Linear combinations of the XPD simulations of the surface structure of each polarization state allow determination of the domain ordering. The best agreement with experiment is found for 55% P + , 38% P − , and 7% P in . The rumpling is smaller at the surface than in the bulk, suggesting that both domain ordering and surface structural changes contribute to screening of the polarization.