Solid-state chemistry silicon-based materials

One of the most important advances in solid state chemistry is the development of silicon-based materials. The Silicon Valley is where the semiconductor industry was bom scientists worked very hard to learn how to purify silicon and arrange the silicon atoms in such a way that they can be used to make a computer chip. At the heart of every single computer, and most electronic devices, is silicon. Just look aroimd you and imagine a world without silicon, it would be a very different place. 

During the course of the last century, it was realized that many properties of solids are controlled not so much by the chemical composition or the chemical bonds linking the constituent atoms in the crystal but by faults or defects in the structure. Over the course of time the subject has, if anything, increased in importance. Indeed, there is no aspect of the physics and chemistry of solids that is not decisively influenced by the defects that occur in the material under consideration. The whole of the modem silicon-based computer industry is founded upon the introduction of precise amounts of specific impurities into extremely pure crystals. Solid-state lasers function because of the activity of impurity atoms. Battery science, solid oxide fuel cells, hydrogen storage, displays, all rest upon an understanding of defects in the solid matrix. 

Crystalline and amorphous silicons, which are currently investigated in the field of solid-state physics, are still considered as unrelated to polysilanes and related macromolecules, which are studied in the field of organosilicon chemistry. A new idea proposed in this chapter is that these materials are related and can be understood in terms of the dimensional hierarchy of silicon-backbone materials. The electronic structures of one-dimensional polymers (polysilanes) are discussed. The effects of side groups and conformations were calculated theoretically and are discussed in the light of such experimental data as UV absorption, photoluminescence, and UV photospectroscopy (UPS) measurements. Finally, future directions in the development of silicon-based polymers are indicated on the basis of some novel efforts to extend silicon-based polymers to high-dimensional polymers, one-dimensional superlattices, and metallic polymers with alternating double bonds. 

The volume opens with an account of PISEMA Solid-State NMR Spectroscopy by A. Ramamoorthy, Y. Wei and D.-K. Lee, this is followed by a review of 3D Structure Elucidation Using NMR Chemical Shifts by U. Sternberg, R. Witter and A. S. Ulrich, next comes an account of Se NMR Spectroscopy and Its Applications in Chemistry by H. Duddeck, the following report is on Structural Studies of Polymer Blends by Solid State NMR from H. Kurosu and Q. Chen, finally there is a discussion of the Structural Characterization of Silicon-based Polymer Materials by Solid-State NMR Spectroscopy from S. Kuroki, H. Kimura and I. Ando. 

Polymer derived ceramics have been known for the last four decades and are prepared via solid-state thermolysis of preceramic polymers. They exhibit a unique combination of remarkable properties due to their covalent bonding and amorphous nature. Thus, silicon oxycarbide (SiOC) and silicon carbonitride (SiCN) based ternary PDCs have been shown to possess outstanding high-temperature properties such as stability with respect to crystallization and decomposition, oxidation and corrosion resistance as well as excellent thermomechanical properties (e.g., near zero steady state creep resistance up to temperatures far beyond 1000 °C). Their properties are directly influenced by the chemistry and the architecture of the preceramic precursors, thus there is an enormous potential in tuning the microstructure and properties of the PDCs by using tailored polymers. Furthermore, suitable chemical modification of the preceramic precursors leads to quaternary and multinary ceramics, as it has been shown for instance for silicon boron carbonitride ceramics in the last 25 years, which in some cases exhibit improved properties as compared to those of the ternary materials. 

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