Nitrides conversion

Variations of nitride conversion percentage with (a) nitrogen pressure and sam-and (b) preheating temperature and diluent content. 

Lithium Nitride. Lithium nitride [26134-62-3], Li N, is prepared from the strongly exothermic direct reaction of lithium and nitrogen. The reaction proceeds to completion even when the temperature is kept below the melting point of lithium metal. The lithium ion is extremely mobile in the hexagonal lattice resulting in one of the highest known soHd ionic conductivities. Lithium nitride in combination with other compounds is used as a catalyst for the conversion of hexagonal boron nitride to the cubic form. The properties of lithium nitride have been extensively reviewed (66). 

Fig. 7.8. High temperature conversion of a-silicon nitride with an MgO additive to the p-pha.se is thought to be a consequence of dissolution of the a phase in a magnesium silicate with subsequent recrystallization from the melt. Enhanced dissolution rate should then strongly influence a. p conversion [84B01].

Fig. 7.9. Measurements of the degree of conversion of ct p silicon nitride at a fixed time and various temperatures are thought to show the strong influence of shock modification on the high temperature dissolution [84B01].

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. "... 

Entries on new materials, including re-cyclate plastics, fullerenes, hard-surfaced polymers, dendrimers, transflective materials, rapid prototyping materials, silicone nitride, supercritical fluids, bulk molding compounds, conversion coatings, folic acid, replacements for chloro-fluorocarbons ... 

Re-use of the catalyst The high activity of the solid catalysts also allows one to re-use high surface area titanium nitride several times. By centrifugation, the solid can be separated and used in a new reaction. The catalyst was used up to four times. Figure 19.10 shows the conversion of DPE with time. 

Boron-containing nonoxide amorphous or crystalline advanced ceramics, including boron nitride (BN), boron carbide (B4C), boron carbonitride (B/C/N), and boron silicon carbonitride Si/B/C/N, can be prepared via the preceramic polymers route called the polymer-derived ceramics (PDCs) route, using convenient thermal and chemical processes. Because the preparation of BN has been the most in demand and widespread boron-based material during the past two decades, this chapter provides an overview of the conversion of boron- and nitrogen-containing polymers into advanced BN materials. 

There has long been interest in investigating Fe- and Co-based catalysts for oxygen reduction because of their role as highly effective enzymes for oxygen transport and conversion in biological systems. More recently, additional interest has been centered on alternative precious metals, metal oxides, and metal carbides and nitrides as possible oxygen reduction catalysts. 

The main products from the reaction between phosphine and atomic nitrogen are molecular hydrogen and phosphorus nitride (PN), which is formed in the a form For the conversion of one mole of phosphine into (PN), two atoms of nitrogen appear to be necessary. The primary step is the formation of PH2 radicals which react further with the nitrogen atoms to give the nitride... 

Antonelli and co-workers have recently demonstrated that room temperature stoichiometric ammonia synthesis is possible with their mesoporous titanium and niobium oxide catalysts. In this study, they proposed that the ammonia species are formed via the reaction activated nitrogen with the underlying moisture of the support. Reversible, inter-conversion of and NH2 species via exposure to moist air for aluminophosphate oxynitride catalysts has been observed by FTIR and XPS by Marquez and co-workers. There has been a lot of interest in the literature in the development of novel routes for the low temperature stoichiometric conversion of nitrogen to ammonia, e.g.. However, in principle this could be realised by the nitridation of Li, followed by hydrolysis, although the kinetics would be very slow. 

Molybdenum nitride itself has been dispersed on platinum clusters dispersed in EMT zeolite. In this study, coverage of platinum particles by molybdenum deposition was investigated and was reported to suppress the activity for benzene hydrogenation and enhance the heptane conversion. With respect to bare Pt for heptane conversion, the aromatisation activity was reduced, whereas isomerisation and hydrogenolysis were observed. 

Scheme 9.10 Conversion of polyborazylene 9.16 into hexagonal boron nitride.

Combustion of undiluted Ti or Ti + 0.5 C compacts in gaseous nitrogen at pressures up to 1.4 MPa resulted in incomplete conversion to the nitride or carbonitride. The product included TiN and solid solutions of nitrogen in titanium for the Ti samples and a single non-stoichiometric titanium carbonitride phase for the Ti + 0.5 C samples. 

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