Oxygen heat treatment

Gettering is a black art. It consists in forcing selected impurities (typically, transition metals) to diffuse toward unimportant regions of tlie device. This is often done by creating precipitation sites and perfoniiing heat treatments. The precipitation sites range from small oxygen complexes to layers such as an A1 silicide. The foniiation of such a... 

Strontium titanate [12060-59-2] SrTiO, becomes an n-ty e semiconductor when additional electrons are created on the Ti lattice sites by donor doping or when oxygen is removed from the material through heat treatment in a reducing atmosphere. The mobiUty of the electrons in the conduction band is about 6 crc] j(V-s). On the other hand, when ZnO is reduced, 2inc interstitials are formed and these act as donors, each yielding a free electron. 

Multiphase gold or palladium-based alloys never show dissolution of Au or Pd but often exhibit progressive surface ennoblement due to selective dissolution of copper or silver from the outer 2-3 atomic layers Heat treatment often decomposes multicomponent alloys into a Pd-Cu rich compound and an Ag-rich matrix with corrosion of the latter phase in deaerated artificial saliva and S -containing media . Au-Cu-rich lamellae have similarly been observed, again with preferential attack on Ag-rich phases or matrix. These effects presumably arise from the ability of the noble alloy phases to catalyse the cathodic reduction of oxygen . 

Polyacene is classified as a material which does not belong to either soft or hard carbons [84], It is also made by heat-treatment of phenol resin. As the heat-treatment temperature is lower than about 1000 °C, polyacene contains hydrogen and oxygen atoms. It has a conjugated plane into which lithium ions are doped. It was reported that the discharge capacity of polyacene is more than 1000 mAhg. However, there are no practical lithium-ion batteries using polyacene. 

The betalains serve as another example. They are very sensitive to different technological factors. They can only be maintained in foods with short shelf lives, produced with minimum heat treatment, and packaged in a dry state under reduced levels of light, oxygen, and humidity. Betalains have several applications in gelatin desserts, confectionery, dry mixes, poultry, dairy, and meat products. ... 

Accidental admixture of oxygen gas with unstabilised liquid tetrafluoroethylene produced a polymeric peroxide which was powerfully explosive, and sensitive to heat, impact or friction [1], Removal of oxygen by treatment with pyrophoric copper to prevent explosion of tetrafluoroethylene has been claimed [2],... 

Some effects of irradiation on vitamins have been mentioned earlier. It appears that irradiation and heat treatment affect vitamins differendy. Apparendy, vitamins Br B6, B12 and folic acid decompose less under as high a radiation dose as 60 kGy than under autoclaving at 120°Cfor 20 minutes. On the other hand, vitamin C is much more sensitive to irradiation. Generally, the radiosensitive vitamins are also sensitive to light, heat, and oxygen. In fresh foods, the vitamins that are most susceptible to irradiation are A and E. There is also some decomposition of vitamins B, and C. Other vitamins are fairly stable under irradiation. However, for the most part, the vitamins are more susecptible to heat treatment than to irradiation. 

Alumina spheres polluted by carbon residues have been also reactivated by use of microwaves [33]. Their regeneration has been performed in a stream of air and in the presence of silicon carbide as an auxiliary microwave absorber. Microwave heat treatment led to full recovery of the catalyst in times varying from a half to a quarter of the conventional treatments. Regeneration of a commercial Ni catalyst (Ni/Al203) deactivated, presumably, by coke formation, by means of a flow of hydrogen or oxygen and water vapor under the action of microwave irradiation was, however, unsuccessful [34]. 

Gas phase oxidation is commonly used for the purification of CNTs. The method proposed by Ebbesen et al. [20] uses heat treatment of crude CNT products under a gas containing oxygen. This method has been explored extensively because it can yield the most highly graphitized tubes without being contaminated by the metal catalyst. 

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