Electron Energy-Loss Near-Edge Structure of Metal-Alumina Interfaces

Abstract

Abstract. 2014 The physical properties of metal-ceramic composites are strongly affected by the local chemistry and atomic bonding across the interface. Information on both are contained in the energy-loss near-edge structure. The spectral component specific for the interface can be obtained by the spatial-difference technique. This method was applied for the investigation of two different interfaces, namely Al/Al2O3 and Cu/Al2O3. The Al-L2,3 edge at the Al/Al2O3 interface shows a characteristic energy-loss near-edge structure which was compared to multiple scattering calculations for Al(O3Al) tetrahedra with various Al-Al bond lengths. Good agreement with the experimental data was found for a cluster with an Al-Al bond length larger than the Al-O distance which is nearly that of amorphous Al2O3. No interface-specific component could be detected at the Al-L2,3 edge of the Cu/Al2O3 interface. However, the energy-loss near-edge structure of the Cu-L2,3 edge indicates that Cu exists at the interface in a Cu1+ state and that the chemical bond is established at the interface between Cu and O atoms.

Narrow-band red-emitting Sr[LiAl3N4]:Eu2+ as a next-generation LED-phosphor material

“…4b. The onset at 73 eV of the Al-L 2,3 edge overlaps with the Li-K edge, but the shape of the Al edges correlates with data published in the literature, the peak maximum being determined to be 85 eV, which is in good accordance with the values obtained from the literature 29 . The Li-K edge shows a slight deviation compared to the literature data; for example, Li x TiP (x = 2-11), Li 2 CaSi 2 N 4 or Li 2 SrSi 2 N 4 , due to different bonding types 30,31 .…”

Evidence of oxygen segregation at Ag/MgO interfaces

“…to extract the interface speci®c part of the ELNES, the spatial dierence technique [28] was applied: as the spectrum of the interface also contains information from the adjacent matrix and precipitation areas (the probe diameter is larger than the thickness of the interface layer) this method requires reference spectra of the precipitation areas in addition to the interface spectrum. Subtracting the suitably scaled (to prevent unphysical negative counts) and background-eliminated reference spectra from the interface spectrum provides information as to the interfacial atoms, particularly, their chemical environment or oxidation state, which may dier from that of the bulk material.…”

“…Electron energy loss spectroscopy (EELS) is also useful in performing such examinations, since it allows the bonding states of chemical elements at interfaces to be determined on a nanometre scale by analysing the near edge ®ne structure (ELNES) of an EELS spectrum [7,24,28,29,36,37]. Moreover, quantitative volumetric measurements (sorption and desorption of oxygen) [25] and a special electrochemical technique applicable to the matrix metal palladium (high hydrogen permeability) have been employed [25± 27].…”

Determining the Location and Role of Al in Al-Modified TiO2 Nanoparticles Using Low-Temperature Heat Capacity, Electron Energy-Loss Spectroscopy, and X-ray Diffraction

“…The Al L 2,3 and L 1 ELNES edges arise from electronic transitions involving core electrons and are centered at about 80, 95, and 120 eV [43][44][45] . Figure 7 shows 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 of Al 2 O 3 suggesting that the atomic character immediately surrounding the Al atoms appears 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60...…”

“…At low dopant concentrations, Al is not observed (see figure 7) suggesting that it is dispersed as would be expected for a solid solution of 5-14 mol% Al in TiO 2 . In both 22 mol% Al samples and 50 mol% Al DCR, Al is observed as broad peaks quite different from the Al L edge of pure Al 2 O 3 but somewhat similar to highly disordered Al at interfaces[44][45] . In 50 mol% Al DRC, the Al L edge appears very similar to that…”