Stmeture factors

Guggenheim S, Kato T (1984) Kinoshitalite and Mn phlogopites Trial refinements in subgroup symmetry and further refinement in ideal symmetry. Mineral J 12 1-5 Giiven N (1971a) Stmetural factors controlling stacking sequences in dioctahedral micas. Clays Clay Minerals 19 159-165... 

Besides polybutadiene, a similar behavior of the static stmeture factor is found for instance for polyethylene in the molten state, poly(ethylene propylene), poly(ethylene oxide), polyisobutylene,or poly(vinyl chloride). For these polymers, S(Q) in the intermolecular region displays one well-defined diffraction peak. For other cases, a peak with a shoulder or even two well-sepatated peaks can be observed in the Q-range characteristic for the intermolecular correlations. Examples for that are polyisoprene (Pl), polycarbonate, polystyrene (PS), 1,2-polybutadiene, poly (vinyl acetate), and poly(n-alkyl methacrylates). " In some cases, the existence of a multipeak stmrture in the intramolecular range of the momentum transfer does not correlate with the existence of bulky or longer side groups. 

These findings underline the fact that the interpretation of the structure factor in terms of atomic correlation is difficult. In the case of complex molecular systems like polymers, the averaged information that can be obtained by measuring S(Q) does not allow conclusions to be drawn about the short-range order details. This means that other sources of information have to be explored to understand the Q-dependence of the static stmeture factor on a molecular level. 

One possibility is the measurement of partial stmeture factors. This can be done by comparing different probes such as X-ray and neutron diffraction. In particular, neutron diffraction... 

The partial density pap = P CaCp, where Ca and cp are the concentrations of the elements. We calculate the stmeture factor Q) by Fourier transforming the gap r) to give the partial structure factors ... 

The crystal stmeture and stoichiometry of these materials is determined from two contributions, geometric and electronic. The geometric factor is an empirical one (8) simple interstitial carbides, nitrides, borides, and hydrides are formed for small ratios of nonmetal to metal radii, eg, < 0.59. 

Although crystal field theory quite successfully rationalizes observed structures of the spinels of the first transition series, it must be applied with care to other examples. In comparing stmetures in which other factors (ionic radii, covalency, etc.) are more dissimilar, d orbital splittings alone generally do not explain the observations. In these cases, a broader analysis is required. 

The second strategy involves stabilization of the mono-Cp r/°-non-benzyl dialkyl metal cation with 7t-arene coordination. The arene coordination becomes the primary stabilization factor enabling the detection or isolation of the mono-Cp dimethyl cations. Thus, the reaction of Cp MMe3 (M = Zr, Hf) with 1 equiv. of B(C6Fs)3 in toluene/hexanes (1 10) solutions at ambient temperature affords the cationic arene complexes [(Gp M(Me)2(7]6-PhMe)][MeB(C6Fs)3] 304 as the solvent-separated ion pairs stabilized by the coordination of the aromatic solvent (Equation (22)).244 The crystal stmeture of the hafnium complex [(Cp Hf(Me)2(7]6-PhMe)][MeB(C6Fs)3] confirms the formation of the separated, discrete ion pairs in which the bent-sandwich cation is coordinated to an 7]6-toluene ligand.245... 

As pointed out before, interfaee stmeture in OFETs is important for both charge injection (metal-semiconductor interface) and charge transport (semi-conductor-dielectric interface). The discussion of the previous section demonstrates that even for the small number of model systems considered here a large variety of sfructures is observed. Because many factors influence the interface and film sfructures, it is difficult to establish general mles. Flowever, a few important observations regarding the stmcture-forming factors can be kept hold of ... 

Rejection of oiganics may be determined by size and charge as well as the same parameters that govern ion rejection. In addition, factors such as molecular conformation and stmeture may play a role. 

An important idea that underpins much of nanotechnology is that by controlling composition, size, and structure at the nanoscale one can engineer almost any desired properties. This is particularly trae for NPs as demonstrated by their many varied technological apphcations. They also have considerable fundamental interest as one can study the emergence of bulk properties (i.e. electronic, chemical, stmctural, thermal, mechanical, and optical) as the number of atoms in the particle increases from one to many thousands. The aim of this chapter is to provide a broad introduction to NP systems, with particular attention paid to stmeture and its connection to various properties (so-called structure-property relationships). This chapter is divided into three main parts. First in Section 2.2, some general issues concerning the atomic structure of NPs and its dependence on various factors, such as particle size and the presence of a support, are discussed. Associated properties of NP systems, such as chemical... 

There are limits, of course, and particularly relevant here is the fact that powder diffraction is not ideal for studying molecular systems. This is due to several factors. Molecular structures frequently have large, low symmetry unit cells, which leads to much peak overlap in the powder pattern. The stmetures under study also frequently... 

Jj is the most simplest and eonvenient and merely one dominating factor Dj is considered whereas it may be inadequate to deal with a complex stmeture as the RSB. Another relative important factor is therefore added into J. Furthermore, two more factors of M2 and are considered in and F3 and in J,. 

The investigation of the stmeture of metal melts has been paid attention to for several deeades by now. On the one hand, the interest is due to the complexity of direct investigation of the stmeture by both experimental and theoretical methods. On the other hand, the understanding of the essence of the processes and the factors influencing them is extremely important for application and is the key for the creation of new materials with unique properties. 

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