Silicon suboxide

Our calculations show that silicon suboxide clusters are the most probable constituent of the vapor, and they have an unsaturated nature and are highly reactive towards bonding with other clusters. Moreover, a silicon suboxide cluster prefers to form a Si-Si bond with other silicon oxide clusters as shown in Figure 10.5... 

Figure 19.1. Representation of silicon suboxide composition in terms of the relative probabilities of RB (solid curves) and RM (dashed lines) model constituents Si(Si4 iOi).

Silicon suboxide species (0 <. v < 2) formed after prolonged AC etching (EAr+ S 6 keV) of stoichiometric SiOi surfaces. 

Titanium silicalite Titanium silicates Titanium-silicon alloy Titanium slag Titanium suboxides... 

The high temperatures of coal char oxidation lead to a partial vaporization of the mineral or ash inclusions. Compounds of the alkali metals, the alkaline earth metals, silicon, and iron are volatilized during char combustion. The volatilization of silicon, magnesium, calcium, and iron can be greatly enhanced by reduction of their refractory oxides to more volatile forms (e.g., metal suboxides or elemental metals) in the locally reducing environment of the coal particle. The volatilized suboxides and elemental metals are then reoxidized in the boundary layer around the burning particle, where they subsequently nucleate to form a submicron aerosol. 

Uhlir (7) suggested that die thick anode film which forms on silicon in aqueous HP solutions below the critical current density is a suboxide of silicon. Faust (27) and Wang (30) also assumed it to be some kind of oxide layer. On the basis of experimental results which indicated that die critical current density was determined by the rate of mass transfer of HP to the silicon, Turner (29) presumed the anode film to be (SiF 2)x ... 

Carbothermal Reactions It is noteworthy that a variety of oxides, nitrides and elemental nanowires can be synthesized by carbothermal reactions. For example, carbon (activated carbon or carbon nanotubes) in mixture with an oxide produces oxide or suboxide vapor species, which react with other reactants (O2, N2 or NH3) to produce the desired nanowires. Thus GaN nanowires are produced by heating a mixture of Ga203 and carbon in N2 or NH3. Silicon nanowires can also be made by heating Si02 with carbon in a suitable atmosphere. 

Figure 10 shows a three dimensional plot of the Si 2p spectrum as a function of silicon dioxide film thickness obtained by sequentially etching a 250 A thick oxide with HF/ethanol (34). Monochromatic Al k-a x-rays were used to excite the spectra in a standard XPS system. Notice that the Si 2p component due to the substrate is observed at about 100 A from the interface because the escape depth is about 38 A for 1386 eV electrons (32). Suboxides at the interface begin to appear as a prominent shift in the 2p components at about 20 A and are present up to the Si surface. Grunthaner, et al. (34) showed that the interfacial region consists of approximately 1 monolayer of Si,0, SiO and Si,0, in a 2 3 2... 

---