Structural chemistry carbides

This volume, which is unique in its coverage, provides a general introduction to the properties and nature of transition metal carbides and nitrides, and covers their latest applications in a wide variety of fields. It is directed at both experts and nonexperts in the fields of materials science, solid-state chemistry, physics, ceramics engineering and catalysis. The first chapter provides an overview, with other chapters covering theory of bonding, structure and composition, catalytic properties, physical properties, new methods of preparation, and spectroscopy and microscopy. 

THE CHEMISTRY OF TRANSITION METAL CARBIDES AND NITRIDES 7.2.1 Electronic structure of dicarbides... 

R. F. Cooper and K. Chyung, Structure and Chemistry of Fibre-Matrix Interfaces in Silicon Carbide Fiber-Reinforced Glass-Ceramic Composites An Electron Microscopy Study, J. Mater. Sci., 22, 3148-3160 (1987). 

Lithium-Structure Compatibility. One of the critical chemistry problems of HYLIFE is the compatibility of structural alloys with the molten liquid of the jet array. Two candidate liquid metals are lithium and Pbg3Lij 7. High-Z metal (such as lead from target debris) will enter the liquid metal and may affect the compatibility. The structural alloy selected in the HYLIFE study is Cr-1 Mo, a ferritic steel. The carbides usually present in this steel are M3C (cementite) and M2C, where M is primarily Fe. Both of these carbides are unstable in lithium. M3C is usually present as platelets within pearlite, the eutectoid structure in pearlitic steel. The most common microstructure for the 2 4 Cr-1 Mo steel is large grains of ferrite with small islands of pearlite. M2C is present as a fine spray of precipitate within large ferrite grains. Lithium... 

Borides Sohd-state Chemistry Carbides Transition Metal Solid-state Chemistry Electronic Structure of Sohds Quasicrystals Structure Property Maps for Inorganic Solids Superconductivity Zintl Compounds. 

Alloys Borates Solid-state Chemistry Carbides Transition Metal Solid-state Chemistry Chalcogenides Solid-state Chemistry Diffraction Methods in Inorganic Chemistry Electronic Structure of Solids Fluorides Solid-state Chemistry Halides Solid-state Chemistry Intercalation Chemistry Ionic Conductors Magnetic Oxides Magnetism of Extended Arrays in Inorganic Solids Nitrides Transition Metal Solid-state Chemistry Noncrystalline Solids Oxide Catalysts in Solid-state Chemistry Oxides Solid-state Chemistry Quasicrystals Semiconductor Interfaces Solids Characterization by Powder Diffraction Solids Computer Modeling Superconductivity Surfaces. 

Ternary phases with structures different from those of the phases of the binary boundary systems are more the exception than the rule. Such phases have been reported in the systems Nb-Mo-N, Ta-Mo-N, Nb-Ta-N, Zr-V-N, Nb-Cr-N, and Ta-Cr-N. Information about ternary transition metal-nitrogen systems is often available for specific temperatmes only. This is even more the case for quaternary nitride systems, which play a role in the production of carbonitride cermets where quaternary compounds of the types (Ti,Mo)(C,N) and (Ti,W)(C,N) are of interest (see Carbides Transition Metal Solid-state Chemistry), as well as in layer technology where titanium nitride-based coatings of the type Ti(C,B,N) are prepared by magnetron sputtering. Layers consisting of ternary compounds of the type (Ti,Al)N and (Ti,V)N also have favorable properties with respect to abrasion resistance. 

The types of molecules considered in this work are those that have structural or chemical features that are manifestly different than are those of their more common oxidation state counterparts. Because of the breadth of this subject, selected examples are presented to illustrate typical behavior. The properties of the types of compounds containing the elements in more typical oxidation states may be found in the Inorganic and Organometallic sections describing each element or gronp and will not be discussed in this article. Similarly, minerals, metal phosphides, metal carbides, and compounds where the oxidation state of the element is low based on formal electron counting techniques (as in some catenated Catenation group 14 compounds), but that do not result in unusual chemistry, are not included. 

Photoluminescence techniques will be applied to a broader range of systems, particularly oxide-supported sulfides (because of their important role in hydrotreating catalysis) as well as unsupported or oxide-supported (oxi)carbides or (oxi)nitrides (because of their growing importance as substitutes for noble metals and because they have metallic and acidic functions). Moreover, improved procedures for preparing catalytic materials will enable the design of tailored oxides with better defined characteristics, such as size, composition, and structure. The accumulation of data concerning the behavior of surface anions will also lead to a more refined view of the coordination chemistry of anions of nontransition elements. 

Although the silicon atom has the same outer electronic structure as carbon its chemistry shows very little resemblance to that of carbon. It is true that elementary silicon has the same crystal structure as one of the forms of carbon (diamond) and that some of its simpler compounds have formulae like those of carbon compounds, but there is seldom much similarity in chemical or physical properties. Since it is more electro-positive than carbon it forms compounds with many metals which have typical alloy structures (see the silicides, p. 789) and some of these have the same structures as the corresponding borides. In fact, silicon in many ways resembles boron more closely than carbon, though the formulae of the compounds are usually quite different. Some of these resemblances are mentioned at the beginning of the next chapter. Silicides have few properties in common with carbides but many with borides, for example, the formation of extended networks of linked Si (B) atoms, though on the other hand few silicides are actually isostructural with borides because Si is appreciably larger than B and does not form some of the polyhedral complexes which are peculiar to boron and are one of the least understood features of boron chemistry. 

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