Transition nitrides

An extensive compilation of the crystal structures of transition metal carbides is found in Pearson s Handbook. Ward has discussed the structures of carbides extensively. Epicier and de Novion have suimnarized the results of investigations on ordering in transition metal carbides. Lengauer recently reviewed the knowledge on transition metal carbides and carbonitrides. For a comparison of close-packed transition metal carbides with close-packed transition nitrides, see Nitrides Transition Metal Solid-state Chem istry. 

P Ettmayer, A Vendl. Phase equilibria and crystal structures of transition nitrides. In RK Viswana-dham, DJ Rowcliffe, J Gurland, eds. Science of Hard Materials. New York Plenum, 1983, p 47. 

Figure 11 High-temperature thermal expansion of various transition nitrides. (From Ref. 41.)...

Wallace C H 1998 The rapid solid-state synthesis of group III and transition metal nitrides at ambient and high pressures PhD Dissertation University of California, Los Angeles... 

Nitride Color Lattice Density, Hardness Mp, °C Heat Coefficient Electrical Transition... 

Although there are several hundred biaary nitrides, only a relative few ternary bimetallic metal nitrides are known (6). A group of ternaries of the composition where M is an alkah, alkaline-earth, or a rare-earth metal and M is a transition or post-transition metal, have been synthesized (6). 

Magnesium reacts slowly at lower temperatures to give the amide, as do all active metals this reaction is catalyzed by transition metal ions. Aluminum nitride [24304-00-5] AIN, barium nitride [12047-79-9] Ba2N2, calcium nitride [12013-82-0] Ca2N2, strontium nitride [12033-82-8], Sr2N2, and titanium nitride [25583-20-4], TiN, may be formed by heating the corresponding amides. 

Reaction spraying is also being widely explored. In this case new compositions or particle surface reactions providing enhanced coating properties, eg, nitrides for wear resistance, are achieved while the particle is in transit. 

Reactions of boron ttihalides that are of commercial importance are those of BCl, and to a lesser extent BBr, with gases in chemical vapor deposition (CVD). CVD of boron by reduction, of boron nitride using NH, and of boron carbide using CH on transition metals and alloys are all technically important processes (34—38). The CVD process is normally supported by heating or by plasma formed by an arc or discharge (39,40). 

The measures of solid state reactivity to be described include experiments on solid-gas, solid-liquid, and solid-solid chemical reaction, solid-solid structural transitions, and hot pressing-sintering in the solid state. These conditions are achieved in catalytic activity measurements of rutile and zinc oxide, in studies of the dissolution of silicon nitride and rutile, the reaction of lead oxide and zirconia to form lead zirconate, the monoclinic to tetragonal transformation in zirconia, the theta-to-alpha transformation in alumina, and the hot pressing of aluminum nitride and aluminum oxide. 

Unlike nitric oxide, NO, the monomeric radical sulfur nitride, NS, is only known as a short-lived intermediate in the gas phase. Nevertheless the properties of this important diatomic molecule have been thoroughly investigated by a variety of spectroscopic and other physical techniques (Section 5.2.1). The NS molecule is stabilized by coordination to a transition metal and a large number of complexes, primarily with metals from Groups 6, 7, 8 and 9, are known. Several detailed reviews of the topic have been published. ... 

A variety of routes is available for the preparation of metal-thionitrosyl complexes. The most common of these are (a) reaction of nitride complexes with a sulfur source, e.g., elemental sulfur, propylene sulfide or sulfur halides, (b) reaction of (NSC1)3 with transition-metal complexes, and (c) reaction of [SN]" salts with transition-metal complexes. An example of each of these approaches is given in Eq. 7.1,... 

The conversion of coordinated NSCI into a nitrido ligand provides a useful synthesis of transition-metal nitrides. For example, treatment of ReCl4(NSCl)(POCl3) with triphenylphosphine generates the nitrido complex ReNClaCPPhsla. "... 

Several patents dealing with the use of volatile metal amidinate complexes in MOCVD or ALD processes have appeared in the literature.The use of volatile amidinato complexes of Al, Ga, and In in the chemical vapor deposition of the respective nitrides has been reported. For example, [PhC(NPh)2]2GaMe was prepared in 68% yield from GaMes and N,N -diphenylbenzamidine in toluene. Various samples of this and related complexes could be heated to 600 °C in N2 to give GaN. A series of homoleptic metal amidinates of the general type [MIRCfNROilnl (R = Me, Bu R = Pr, BuO has been prepared for the transition metals Ti, V, Mn, Fe, Co, Ni, Cu, Ag, and La. The types of products are summarized in Scheme 226. The new compounds were found to have properties well-suited for use as precursors for atomic layer deposition (ALD) of thin films. 

Nitrides of Metals of the First Transition Series R. Juza... 

Borides, in contrast to carbides and nitrides, are characterized by an unusual structural complexity for both metal-rich and B-rich compositions. This complexity has its origin in the tendency of B atoms to form one- two-, or three-dimensional covalent arrangements and to show uncommon coordination numbers because of their large size (rg = 0.88 10 pm) and their electronic structure (deficiency in valence electrons). The structures of the transition-element borides are well established " . 

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