Doped various additives

Historically, materials based on doped barium titanate were used to achieve dielectric constants as high as 2,000 to 10,000. The high dielectric constants result from ionic polarization and the stress enhancement of k associated with the fine-grain size of the material. The specific dielectric properties are obtained through compositional modifications, ie, the inclusion of various additives at different doping levels. For example, additions of strontium titanate to barium titanate shift the Curie point, the temperature at which the ferroelectric to paraelectric phase transition occurs and the maximum dielectric constant is typically observed, to lower temperature as shown in Figure 1 (2). 

As it has been mentioned in Chapter 1, application of various additives to the surface of adsorbent is effective from the stand-point of obtaining the required selectivity to a specific type of active particles. Thus, doping the surface of ZnO by zinc made it possible to reduce the sensitivity of such sensors to H-atoms and, vice versa, increase to O-atoms. The highest selectivity is obtained at a specific doping degree [5]. 

A typical coating contains iron oxides (sometimes doped with cobalt or chromium), a polymer system that acts as a binder, various additives (including up to 1.5% lecithin on a dry solids basis), and solvents such as methyl ethyl ketone and cyclohexanone (454 58). This material is milled into a dispersion and deposited onto the tape and dried. 

The iron tricarbonyl stabilized form of 2-formylbutadiene (56) reacts with various organometallic reagents to produce diastereomeric mixes of products (57a) and (576). While the trend is such that Gri-gnard reagents are nonselective, organolithiums tend to add predominantly from the exo) face away from the bulky iron tricarbonyl group, especially when doped with additional LiBr. Interestingly, the... 

The process of ethane oxidative chlorination imposes heavy demands on the catalysts. The conventional salt supported catalysts are composed of Cu, K, Ca, Mn, Co, Fe, Mg, and other metal chlorides containing various additives these salts are precipitated on alumina, zeolites, silica gel, and other supports. Catalytic systems that represent solid solutions of iron cations in the lattice of the a-A Oa and a-Ct203 phases doped with cations, such as K, Ba, Ce, and Ag are also known [7]. 

This oxidation catalyst can be both n and p doped by various additives. The activation energy of the reaction increases with n-type doping and decreases on p-type doping. 

The effect of the additives on alumina has been widely studied with respect to the following parameters stabilizing elements, concentrations (0,5 - 20% wt.), type of the precursor (salt, hydroxide, oxide), procedure of introduction, conditions of the subsequent thermal treatment. The controversy in the role and mechanism of various additives is caused by the fact that various researchers use different doping methods and different method producing alumina. Moreover, the term y-alumina is frequently used to designate any transition forms which occur first in the decomposition sequence, i.e. x, P y-AbOa. 

The incorporation of functionalized CNTs into composite membranes are mostly carried out on flat sheet membranes [129, 130]. For considering the potential influences of CNTs on the physicochemical properties of dope solution [131] and change of membrane formation route originated from various additives [132], it is necessary to study the effects of CNTs on the morphology and performance. 

Mention has already been made of the application of alkoxycyclophos-phazenes, [NP(OR)2] , as flame retardants in rayon. Although the methoxy-derivatives, with their high phosphorus content, were expected to be most efficient in this respect, their water solubility proved a major shortcoming. However, the n-propoxy series, [NP(OPr )2] ( mainly 3—6), were found to impart excellent flame resistance and were well retained by rayon. The cyclophosphazene alkoxides were obtained by the addition of sodium-n-propoxide to the chloride homologues, (NPCl2)n, and were added to the viscose dope before the rayon was spun. The flame resistance imparted by various amino- and thioalkoxy-derivatives was also tested, but found to be inferior to the results obtained with alkoxy-deriva-tives. Several patent applications have resulted from work on this topic. ... 

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