Chemical binary material films

Later on, this concept was extended to precursors containing both elements of the desired material already connected by a chemical bond in a single molecule. Such precursors are mainly referred to as single source precursors. Their potential application for the deposition of thin films of the corresponding binary materials by MOCVD processes could be demonstrated. In particular Lewis acid-base adducts R3M—ER3 and four- and six-membered heterocycles [R2MER x (Fig- 1) have been in the focus of research groups both in industry and university. Consequently, the development of powerful synthetic pathways for the preparation of such precursors has been forced. 

The experimental conditions of preparation deeply affect the electrical properties of the final material. A polypyrrole sample with a conductivity of 328 S cm has been obtained by careful control of the oxidation potential in a binary solution of acetonitrile and methanol [88]. Different chemical characteristics of poly pyrrole are obtained by varying the initial concentrations of Fe " and pyrrole in the polymerization solution [89]. Polypyrrole obtained by chemical oxidation is usually in the form of a black powder. Freestanding poly pyrrole films were prepared at room... 

It has been demonstrated that the classical equihbiimn defect chemical concepts derived for binary compounds can be apphed to ternary and multinary compoimds. In the case of multicomponent materials, the space charge effects will become very important in cases in which the dimensions are no longer large compared with the thickness of the space charge layers, as in extremely thin films or in stractirral and functional ceramics with crystallites of nanometer dimensiorts. The formation of latent images in silver halide photography represents a prelude to effects of point defects in nanostractured materials, and is related to enlarged concentrations of point defects in botmdary layers. 

Chapter 8 details the modeling of the self-assembly of ternary blends encompassing photosensitive chemical reactions that create defect-free, hierarchically ordered materials. Starting with a brief review of literature, this chapter provides a description of theoretical models and then shows how one can control the evolution of such systems by varying the reaction rate coefficients in a specified manner. A further discussion on the formation of defect-free structures in the binary and ternary systems via a combination of stationary and moving light sources is given. Then, description is provided on the use of a photomask to control the structure formation within thin films of ternary blends. 

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