Surface energy trends

The physical origin of this structural flexibility of the FeO overlayer is still unclear, the more so since no clear trend is observable in the sequence of lattice parameters of the coincidence structures. The FeO(l 11) phase forming up to coverages of 2-3 ML is clearly stabilized by the interactions with the Pt substrate since FeO is thermodynamically metastable with respect to the higher iron oxides [106,114], FeO has the rock salt structure and the (111) plane yields a polar surface with a high surface energy [115], which requires stabilization by internal reconstruction or external compensation. The structural relaxation observed in the form of the reduced Fe—O... 

The surface force trend resembles that of the interaction energy as a function of the distance between two mica surfaces bearing polymer brushes as obtained with the surface forces apparatus (SFA) (e.g. [242]). Such a similarity between polymer brushes symmetrically compressed by different phases is not unexpected. 

An example of a random multiblock copolymer is found in the study of HMS/DMS copolymers where the DMS bulk content was varied from 27%, to 57.2% to 72.5% by weight. XPS ( 0 ) studies established that trends in the surface composition and morphology were similar in nature to both the PS/PEO diblock and triblock systems. In other words, the polymer components are segregated into isolated domains and the lower surface energy component dominates the immediate surface. By plotting the results from the XPS ( 6 ) studies on compositional variations with depth and extrapolating to an angle of 0 = 90, or just the immediate outer surface... 

A number of papers have examined the adsorption of metal atoms other than Au on MgO. Fernandez et al. systematically studied all first row transition metals (K-Zn) on defect-free MgO(lOO), at coverages corresponding to epitaxial overlayers and at coverages representative of isolated atoms on the surface. The trends in adsorption energy for these species were dominated by the interaction between the adsorbed atoms and O atoms in the surface, although interactions with adjacent surface Mg atoms also contribute for the larger adsorbed species e.g. K and V). It is not clear from these results whether these trends would transfer in a simple way to defects on the oxide surface. 

The energies in the figure exhibit a parabolic-like behavior as a function of the atomic number. Such a behavior is explained in terms of the occupation of the valence d-band by the Friedel model [29,30] in which the surface energies follow the same trend as the corresponding cohesive energies and can be estimated from... 

Iridium follows the trend for formation of underlayer alloys for elements with similar metallic radii/crystal structure to copper yet having considerably higher surface energy. However, Ir differs from the tendency for c(2x2) underlayer ordering shown by Pd and Pt. In this case, formation of one-dimensionally close packed Ir rows may occur due to the higher Ir-Ir bond energy combined with the slightly smaller f.c.c. mismatch of 6.2%. 

LDPE films, a consistent trend between forces and surface energy (as assessed by water contact angle measurements) was established (Fig. 4.8b). 

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