Nonstoichiometric carbides

In the elementary reactions of the pyrolysis, the atomic carbon is formed first. Then it transforms into the final product, whether it be soot, graphite, carbon nanofibers, or so forth. Why does the presence of catalysts make it possible to grow carbon nanofibers or nanotubes instead of soot In many cases, this is the so called carbide cycle that is characteristic of the catalytic process of hydrocarbon pyrolysis that is responsible for the growth of the elongated structures but not soot particles. The primary car bon atoms produced by pyrolytic decomposition of the hydrocarbon molecules are dissolved in the metal particle of the active catalyst compo nent to form a nonstoichiometric carbide (the carbon solution in the... 

We have adapted this function to a single-phase FGM based on nonstoichiometric titanium carbide TiCj. It is possible to treat the nonstoichiometric carbide as a solution of titanium carbide of high carbon content (TiCo.98) and added titanium. Note that x=Mc/MTi where M stands for the number of moles, and ja, the molecular weight is equal to 48, 12 and 59.76 g/moleforTi, C and TiCg gg, respectively. The value of jc can written as ... 

INVESTIGATION OF THE CARBON K AND METAL EMISSION BANDS AND BONDING FOR STOICHIOMETRIC AND NONSTOICHIOMETRIC CARBIDES ... 

Electronic structure and properties of nonstoichiometric carbides and nitrides... 

Kolpachev, A. B. (1988). Electronic Structure of Nonstoichiometric Carbides and Carbonitrides of Transition Metals, Rostov-on-Don Rostov-on-Don, University Publishing House. 

The remarkable effects caused by vacancies on the properties of carbides and nitrides have given rise to numerous experimental and theoretical studies. In the present overview we will concentrate on theoretical approaches only, although experimental results are imperative as a basis for testing theoretical models and methods. A complete list of references of computations on nonstoichiometric carbides and nitrides can be found in the book of Gubanov et al. (7). An essential problem in the theoretical investigations of the electronic structure of the substoichio-metric materials is a proper description of the vacancy-containing phases. Various concepts and models have been devised to treat the vacancy problem. Essentially four different types of approaches can be distinguished. 

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