Chlorination-nitridation reactions

To lower the deposition temperature, CVD processes enhanced by plasma [48-58] and laser [55-58] have been investigated. Low-resistivity (< 40 pQ cm) TiN was deposited by Akahori et al. [59] using TiCL in an electron-cyclotron resonance (ECR) plasma process (Ts b = 540°C, microwave power = 2.8 kW). All films had stoichiometric composition with low chlorine concentrations of 0.16 at. % as determined by ICP-MS. This indicates that the nitridation reaction of TiCU is enhanced enormously by the ECR plasma. 

Chlorination. Historically, the production of zirconium tetrachloride from zircon sand involved first a reduction to carbide nitride (see above) followed by the very exothermic reaction of the cmshed carbide nitride with chlorine gas in a water-cooled vertical shaft furnace ... 

Sihcon carbide is comparatively stable. The only violent reaction occurs when SiC is heated with a mixture of potassium dichromate and lead chromate. Chemical reactions do, however, take place between sihcon carbide and a variety of compounds at relatively high temperatures. Sodium sihcate attacks SiC above 1300°C, and SiC reacts with calcium and magnesium oxides above 1000°C and with copper oxide at 800°C to form the metal sihcide. Sihcon carbide decomposes in fused alkahes such as potassium chromate or sodium chromate and in fused borax or cryohte, and reacts with carbon dioxide, hydrogen, ak, and steam. Sihcon carbide, resistant to chlorine below 700°C, reacts to form carbon and sihcon tetrachloride at high temperature. SiC dissociates in molten kon and the sihcon reacts with oxides present in the melt, a reaction of use in the metallurgy of kon and steel (qv). The dense, self-bonded type of SiC has good resistance to aluminum up to about 800°C, to bismuth and zinc at 600°C, and to tin up to 400°C a new sihcon nitride-bonded type exhibits improved resistance to cryohte. 

Waterfeld, A. et al., J. Chem. Soc., Chem. Comm., 1982, 839 Reaction of chlorine fluoride with trifluorosulfur nitride is rather hazardous and may lead to violent explosions. A safer alternative preparation is to use chlorine and mercuric fluoride in place of chlorine fluoride. 

Rhenium(VI) nitride compounds can be generated by oxidation of rhenium(VI) complexes with chlorine or bromine. The products formed are often unstable and ligand exchange reactions with CP or Br lead to a complex mixture of Re compounds. Oxidation of the rhenium(V) complex [ReN(PPh3)Cl(cpCo PO(OR)2 3)] with Ag(BF4), however, yields [ReN(PPh3)Cl(cpCo- P0(0R)2)3)](BF4) (53) in good yields. ... 

The SiH4 in reaction (3) can be replaced by an organosilicon compound. From chlorinated silane (SiH2Cl2) and NH3, silicon nitride UFPs were synthesized according to the following three routes, depending on both the temperature and the NH3 injection site—below, into, and above the laser beam (66) ... 

Since nitrides have lower heats of formation than oxides, the reaction between chlorine and nitrides will be more complete than between chlorine and oxides. Nitrides react with chlorine to give chlorides and nitrogen. Chlorine, in fact, can displace all negative elements from their compounds, with the exceptions of oxygen and fluorine only. 

The vanadium tetrachloride distils over and is purified from any ferric chloride present either by distillation or by extraction of the product with carbon tetrachloride, in which only the vanadium halide is soluble.2 Sulphuryl chloride, thionyl chloride, sulphur monochloride, and phosgene can all be used in the last reaction instead of chlorine, and the ferrovanadium also can be substituted by vanadium carbide, V4C3,3 nitride, VN,4 subsilicide, V2Si,5 disilicide, VSi2,8 or pentoxide.7... 

In general, the stable thermodynamic products of ordinary flames have little worth, but many of the uncommon flames have products of value. The chlorination of hydrocarbons may be carried out in a flame process which was recently announced (A4). A most fascinating example is the formation of boron nitride from the flame reaction between diborane and hydrazine, two compounds which are ordinarily thought of as fuels (B2, VI). The stabilization of this flame depends upon the proper preparation of the premixed gases, since a solid adduct between the reactants prevents flame stabilization if the preflame residence time is too great. 

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