Poly crystallinity extent

Since compound layers are poly crystalline, grain boundary diffusion may to some extent affect both their morphology and growth kinetics. Grain boundary diffusivities of the components of any compound are known to be a few orders of magnitude higher than appropriate lattice ones. 

According to the standard electrochemical potentials (Table 1), with Cu/Cu2+ and Ru/Ru3+ couples, the amount of ruthenium deposited on metallic copper will be small, whereas the redox reaction carried out in presence of platinum or gold salts will occur to a large extent. On the other hand, for electrodes of first type (metal immersed in a solution of a salt of that metal), the standard electrochemical potentials as defined by thermodynamics are calculated with regard to a poly-crystalline metallic phase of infinite size. However, in the case of small metallic particles, characterized by metallic atoms of different coordination numbers, the notion of a local potential can be introduced. That no-... 

In polymers that exhibit tacticity, the extent of the stereoregularity determines the crystallinity and the physical properties of the polymers. The placement of the monomer units in the polymer is controlled first by the steric and electronic characteristics of the monomer. However, the presence or absence of tacticity, as well as the type of tacticity, is controlled by the catalyst employed in the polymerization reaction. Some common polymers, which can be prepared in specific configuration, include poly(olefins), poly(styrene), poly(methyl methacrylate), and poly(butadiene). 

Fig. 5.21 The effect of PEO and PBO block lengths on the extent of chain folding of the PEO block in the equilibrium states of crystalline PEO,.PBO copolymers (o) unfolded, ( ) one fold, ( ) two folds, ( ) three folds (Mai et al. 1997). The dashed curves approximately delineate the four regions. The data points at m = 0 indicate the equilibrium state (unfolded) of low-molar-mass poly(oxyethylene)s.

Hlavay and Poly k (2005) investigated the surface properties of an iron(III) hydroxide-coated alumina sorbent. Amorphous iron(III) hydroxide was coated onto a mixture of amorphous and various crystalline forms of AI2O3. The iron concentration of the sorbent was 56.1 mmol g-1. Depending on pH, batch experiments indicated that the sorbent was effective with As(V) and to some extent As(III). In a pH 5.6 solution with an ionic strength of 0.1 mmol L-1 and containing 1 mmol L-1 (75 mg As(V) L-1) of As(V), a dosage of 2.5 g sorbent 100 ml-1 of solution sorbed 0.3 mmol As(V) g-1 sorbent (22 mg As(V) g-1 sorbent). In comparison, the sorption capacity of As(III) was only about 0.06 mmol g-1 (4.5 mg As(III) g-1 sorbent) under the same conditions (Hlavay and Poly k, 2005, 76). 

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