Insights into the Electronic Structure of Ceramics through Quantitative Analysis of Valence Electron Energy-loss Spectroscopy

2000 ◽  
Vol 6 (4) ◽  
pp. 297-306 ◽  
Author(s):  
Harald Müllejans ◽  
Roger H. French
Keyword(s):  
Electronic Structure ◽  
Quantitative Analysis ◽  
Energy Loss ◽  
Electron Energy ◽  
Valence Electron ◽  
Interband Transition ◽  
Ceramic Materials ◽  
Scanning Transmission Electron Microscope ◽  
Transition Strength ◽  
Electron Energy Loss

Abstract Valence electron energy-loss (VEEL) spectroscopy was performed on six ceramic materials in a dedicated scanning transmission electron microscope (STEM). Quantitative analysis of these data is described yielding access to the complex optical properties and the electronic structure of the materials. Comparisons are made on the basis of the interband transition strength describing transitions between occupied states in the valence band and empty states in the conduction band. This proves that the quantitative analysis of VEEL data is a competitive and complementary method to be considered when investigating the electronic structure of materials. Possibilities for improvement and extension of the analysis are discussed extensively.

Insights into the Electronic Structure of Ceramics through Quantitative Analysis of Valence Electron Energy-loss Spectroscopy

2000 ◽  
Vol 6 (4) ◽  
pp. 297-306 ◽  
Author(s):  
Harald Müllejans ◽  
Roger H. French
Keyword(s):  
Electronic Structure ◽  
Quantitative Analysis ◽  
Energy Loss ◽  
Electron Energy ◽  
Valence Electron ◽  
Interband Transition ◽  
Ceramic Materials ◽  
Scanning Transmission Electron Microscope ◽  
Transition Strength ◽  
Electron Energy Loss

AbstractValence electron energy-loss (VEEL) spectroscopy was performed on six ceramic materials in a dedicated scanning transmission electron microscope (STEM). Quantitative analysis of these data is described yielding access to the complex optical properties and the electronic structure of the materials. Comparisons are made on the basis of the interband transition strength describing transitions between occupied states in the valence band and empty states in the conduction band. This proves that the quantitative analysis of VEEL data is a competitive and complementary method to be considered when investigating the electronic structure of materials. Possibilities for improvement and extension of the analysis are discussed extensively.

Quantitative analysis of spatially resolved valence electron energy-loss spectra for electronic structure studies of grain boundaries and thin intergranular films

1995 ◽  
Vol 53 ◽  
pp. 314-315
Author(s):  
Roger H. French
Keyword(s):  
Electronic Structure ◽  
Quantitative Analysis ◽  
Spectral Line ◽  
Energy Loss ◽  
Grain Boundaries ◽  
Electron Energy ◽  
Valence Electron ◽  
Transition Strength ◽  
Spatially Resolved ◽  
Electron Energy Loss

The spatial variation of the electronic structure at interfaces is critical to both interatomic bonding at atomically abrupt interfaces such as grain boundaries and also to the development of van der Waals (vdW) attraction forces at partially wetted interfaces. This interfacial electronic structure, as represented by the interband transition strength , can be determined by Kramers Kronig (KK) analysis of either vacuum ultraviolet (VUV) optical reflectance spectra or spatially resolved valence electron energy loss (SR-VEEL) spectra. Quantitative analysis of SR-VEELS requires accurate spectral line shapes coupled with single scattering deconvolution, convergence correction, and KK analysis. Both the energy loss functions (Fig. 1) and the interband transitions (Fig. 2) determined for α-Al2O3 using SR-VEELS compare well with the VUV results. In addition the use of the spectral line scan method, whereby typically 200 SR-VEEL spectra are acquired along a scan line of 20 nm, helps overcome many uncertainties in the data acquisition and analysis.

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

1994 ◽  
Vol 332 ◽  
Author(s):  
Haral MÜllejans ◽  
J. Bruley ◽  
R. H. French ◽  
P. A. Morris
Keyword(s):  
Electronic Structure ◽  
Grain Boundary ◽  
Energy Loss ◽  
Electron Energy ◽  
Valence Electron ◽  
Interband Transition ◽  
Transition Strength ◽  
Structure Information ◽  
Spatially Resolved ◽  
Electron Energy Loss

ABSTRACTValence electron energy-loss (EEL) spectroscopy in a dedicated scanning transmission electron microscope (STEM) has been used to study the Σ11 grain boundary in α-A12O3 in comparison with bulk α-A12O3. The interband transition strength was derived by Kramers-Kronig analysis and the electronic structure followed from quantitative critical point (CP) modelling. Thereby differences in the acquired spectra were related quantitatively to differences in the electronic structure at the grain boundary. The band gap at the boundary was slightly reduced and the ionicity increased. This work demonstrates for the first time that quantitative analysis of spatially resolved (SR) valence EEL spectra is possible. This represents a new avenue to electronic structure information from localized structures.

Electronic Structure Investigations of Metal / SrtiO3 Interfaces Using EELS

2001 ◽  
Vol 7 (S2) ◽  
pp. 304-305
Author(s):  
Klaus van Benthem ◽  
Christina Scheu ◽  
Wilfried Sigle ◽  
Christian Elsässer ◽  
Manfred Rühle
Keyword(s):  
Electronic Structure ◽  
Energy Loss ◽  
Electron Energy ◽  
Scanning Transmission Electron Microscope ◽  
Orientation Relationships ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Analytical Microscopy ◽  
Structure Investigations ◽  
Electron Energy Loss

Ni, Pd and Cr thin films were grown on (100)SrTiO3 surfaces by molecular beam epitaxy at substrate temperatures of TNJ, pd=650°C and Tcr =150°C. Electron energy-loss spectroscopy (EELS) and high resolution transmission electron microscopy (HRTEM) were applied to investigate the local electronic structure and the atomic structure of the interfaces, respectively. Analytical microscopy was carried out with a parallel energy-loss spectrometer (PEELS766) attached to a dedicated scanning transmission electron microscope (STEM) operated at 100keV, which has a point resolution of 0.22 nm. HRTEM studies were performed on a Jeol JEM ARM 1250 operated at 1250keV (0.12 nm point resolution). Conventional TEM and HRTEM experiments showed epitaxial orientation relationships between the thin metal films and the substrate for each interface.The electronic structure of the interfaces in terms of the site- and symmetry projected density of states (PDOS) above the Fermi-level can be extracted from the electron energy-loss near-edge structures (ELNES).

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