Spatially resolved electron energy-loss near-edge structure analysis of a near Σ = 11 tilt boundary in sapphire

Abstract

Abstract. 2014 Spatially resolved electron energy-loss spectra have been recorded from the same E = 11 grain boundary of a high purity sapphire (03B1 -Al2O3) bi-crystal that had previously been examined by high resolution electron microscopy. The energy-loss near-edge structure (ELNES) on the aluminium L2,3 edge of the bulk 03B1 -Al2O3 is consistent with previously published X-ray absorption near-edge spectra (XANES). The presence of the grain-boundary introduces additional fine structure on the L2,3 edge, which is extracted from the dominant bulk spectrum using the chemical-standard "difference" method. A comparison with various spectral "fingerprints" suggests that the structural environment of the Al cations within the boundary plane has a reduced point-group symmetry and coordination number. Quantitative analyses of spectral intensities indicate that the equivalent of a full monolayer of Al cations is involved in the structural change at the boundary. These experimental observations are consistent with a recently calculated low energy relaxed grain-boundary structure.

Quantitative Electronic Structure Analysis of α-AL203 Using Spatially Resolved Valence Electron Energy-Loss Spectra

“…In SR experiments investigating the energy-loss near-edge structure [14], it was found that the transition energy from the aluminium L shell to the conduction band was reduced by more than 1 eV. Hence the latter has to be attributed mainly to a shift in the core level energy.…”

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

“…Larger values for the scaling factor resulted in negative intensities in the energy-loss region between 560 eV and 590 eV Higher energy-losses are influenced by thickness effects and therefore not considered here. [30] and experimental studies [6][7][8]. It provides, therefore, a powerful tool to detect changes in the local coordination of the aluminium atoms at alumina interfaces.…”

“…The resulting difference spectrum represents the ELNES arising from the interfacial atoms. So far the spatial difference technique has been applied to grain boundaries in A1203 [6] and metal-ceramic interfaces [7,8]. Figure 2 however, were not acquired at this particular interface.…”

Change in equilibrium position of misfit dislocations at the GaN/sapphire interface by Si-ion implantation into sapphire. II. Electron energy loss spectroscopic study

“…1(a)] corresponds to a typical feature of α-Al 2 O 3 structure. [1][2][3][4][5] However, the features at 77.8, 78.3, and 79.8 eV in the Al-L 2,3 edge from the PG region [ Fig. 1(b)] do not correspond to pure α-Al 2 O 3 structure, where Al has a pure 6-fold coordination to oxygen, but are even likely to originate in a mix of 4-, 5-, and 6-fold coordinations of Al.…”