Electronic structure of oxide

We shall briefly discuss the electrical properties of the metal oxides. Thermal conductivity, electrical conductivity, the Seebeck effect, and the Hall effect are some of the electron transport properties of solids that characterize the nature of the charge carriers. On the basis of electrical properties, the solid materials may be classified into metals, semiconductors, and insulators as shown in Figure 2.1. The range of electronic structures of oxides is very wide and hence they can be classified into two categories, nontransition metal oxides and transition metal oxides. In nontransition metal oxides, the cation valence orbitals are of s or p type, whereas the cation valence orbitals are of d type in transition metal oxides. A useful starting point in describing the structures of the metal oxides is the ionic model.5 Ionic crystals are formed between highly electropositive... 

Further electronic structure of oxidant and reductant, solvent reogranisation affects the rate of reaction. 

The electronic structure of oxidant and reductant, nature of bridging ligand, formation as well as fission of complex are the factors which can effect the rate of the inner sphere electron transfer mechanism. 

In Tables IV-VI are listed spectral data for binuclear complexes in which the metal ions are joined through a single ligand atom or through a bridging molecule that may be expected to modify the electronic structures of oxidant, reductant, or both. These systems may conveniently be classified according to the degree of certainty of the information that may be deduced from them. 

Articles dealing with the structure and chemistry of solid and crystal surfaces include Tabor (1981) and Forty (1983), who discusses metals and catalysts in particular. The surface of diamond is discussed by Pate (1986), metal oxides by Henrich (1985), transition-metal compounds by Langell and Bernasek (1979), and transition-metal oxides by Henrich (1983). Some of these articles deal with the electronic structures of the surfaces as well as the surface atom geometry the volume edited by Rhodin and Ertl (1979) on the nature of the surface chemical bond and the review paper by Tsukada et al. (1983) on the electronic structure of oxide surfaces concentrate on this aspect. One of the few reviews directed specifically towards minerals is that of Berry (1985). 

Schwarz, K. (1987). Band theoretical studies of the electronic structure of oxides. Phys. Chem. Mineral. 14, 315-19. 

Tsukada, M., J. Adachi, and C. Satoko (1983). Theory of electronic structure of oxide surfaces. Prog. Surf. Sci. 14, 113-74. 

Despite this failure to correctly represent the relative energies of the occupied and unoccupied states correctly, HF and DFT methods have been widely applied in the simulation of the electronic structure of oxides. Examples in the remainder of this chapter will include comments on the reliabihty of these results along with further examples of the use of hybrid functionals. 

The characteristics of the charge distribution in the bulk and in the outer layers are thus key factors to understand the physics of polar surfaces. A zeroth-order description of the electronic structure of oxides is the fully... 

This chapter is concerned with experimental studies of the electronic structure of oxide surfaces. Obviously the complexities of surface electronic structure cannot be understood without first understanding the factors which determine bulk electronic structure the next section outlines some of the key ideas that are needed to describe the bulk electronic structure of oxides. However, it is beyond our scope to dwell at length on experimental determination of bulk electronic structure instead the main focus of the chapter is on aspects of electronic structure associated with surfaces that cannot be understood in terms of the bulk electronic structure alone. The publication of... 

EXPERIMENTAL TECHNIQUES FOR PROBING ELECTRONIC STRUCTURE OF OXIDES... 

Experimental techniques for probing electronic structure of oxides... 

X-ray spectra and electronic structure of oxidized organosulfur compounds. For... 

Grunthaner, F. J, Grunthaner, P. J., Vasquez, R. P., Lewis, B. F., and Maseijian, J. 1979. Local atomic and electronic structure of oxide GoAs and Si02 interfaces using high-resolution XPS. J. Vac. Sci. Technol. 16 1443-1453. 

The electronic structure of oxides and its effect on functional properties... 

Gutierrez-Alejandre, A., Ramirez, J., and Busca, G. The electronic structure of oxide supported tungsten oxide catalysts as studied by UV spectroscopy. Catal Lett. 1998, 56, 29-33. 

The main numerical approaches allowing a calculation of the bulk electronic structure of oxides have been recalled in the first chapter. Treating surface effects requires some care, especially concerning the geometry of the systems... 

Peculiarities in the electronic structure of oxide surfaces are related to the strength of the electrostatic potential which acts on the surface atoms and to the number of broken anion-cation bonds. In a qualitative way, the more open the surface, the stronger the Madelung potential reduction and the less efficient the electron delocalization. 

In the first chapters of this book, the electronic structure of oxides in the bulk and at the surface in the absence of adsorbates has been analyzed, and some theoretical models were given as guidelines for their understanding. It is possible to use them now to point out how the arguments of electronegativity and partial charge developed above are related. 

As stated in the introduction, oxides may cover a wide range of electronic properties, in particular, from insulating ionic to superconducting materials. Consequently, the electronic structure of oxides covers wide band gap insulators, semiconductors, and metals. Examples are MgO or AI2O3, which show properties of insulators with band gaps of 7.5 and 8.5 eV [123], respectively Ti02 or TiOj with semiconducting... 

As an example to study the valence electronic structure of oxides, we consider one of the least disturbed and relaxed surfaces, namely, the MgO(lOO) surface. Figure 15.25a shows angle-resolved photoemission (Volume 1, Chapter 3.2.2) data taken with Hell radiation at different polar angles 9 along the T X azimuth defined in the figure [124]. Via the simple formula... 

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