Cluster morphology

The electronic properties of bimetallic (PdAu, PdPt, and PdZn) NPs were studied using XRD, TEM, XPS, and FTIR of the adsorbed CO. Bimetalhc based catalysts contained 1.5-2 nm NPs with a narrow particle size distribution, but with different NP morphology cluster-in-cluster for PdR and PdZn and core-shell for PdAu [15]. Adchtion of a modifying metal (Au, Pt and Zn) leads to a change of the NP electronic properties as well. 

Ethylene—Dicarboxylic Acid Copolymers. Partial neutralization of copolymers containing carboxyls in pairs on adjacent carbons, eg, ethylene—maleic acid, has been described (11). Surprisingly, there is no increase in stiffness related to neutralization. Salts with divalent metal cations are not melt processible. The close spacing of the paired carboxyl groups has resulted in ionic cluster morphology which is distinct from that of the commercial ionomer family. 

The bulk stmcture of the catalyticaHy active phase is not completely known and is under debate in the Hterature (125,131—133). The central point of controversy is whether (Valone or in combination with other phases is the most catalyticaHy active for the conversion of butane to maleic anhydride. The heart of this issue concerns the role of stmctural disorder in the bulk and how it arises in the catalyst (125,134,135). Most researchers agree that the catalysts with the highest activity and selectivity ate composed mainly of (Vthat exhibits a clustered or distorted platelet morphology (125). It is also generaHy acknowledged that during operation of the catalyst, the bulk oxidation state of the vanadium in the catalyst remains very close to the +4 valence state (125). 

Water molecules combine the tendency to cluster, craze and plasticize the epoxy matrices with the characteristic of easily diffusion in the polymer1 10). The morphology of the thermoset may be adversaly influenced by the presence of the sorbed moisture. The diffusion of the water in glassy polymers able to link the penetrant molecules is, therefore, characterized by various mechanisms of sorption which may be isolated giving useful information on the polymer fine structure. 

A.Y. Stakheev, and L.M. Kustov, Effects of the support on the morphology and electronic properties of supported metal clusters modem concepts and progress in 1990s, Appl. Catal. A 188, 3-35 (1999). 

Sodium carboxymethyl chitin and phosphoryl chitin had most evident influences on the crystallization of calcium phosphate from supersaturated solutions. They potently inhibited the growth of hydroxyapatite and retarded the rate of spontaneous calcium phosphate precipitation. These chitin derivatives were incorporated into the precipitate and influenced both the phase and morphology of the calcium phosphate formed (flaky precipitate resembling octacalcium phosphate instead of spherical clusters in the absence of polysaccharide) [175]. 

The MD simulations provided the necessary thermodynamic information to obtain the equilibrium configurations of the films. Often the deposition process will produce films which are not in the equilibrium configuration, and then the problem is to determine the stablity of these films against changes in morphology. Here simulations can also be helpful, since data on the surface energies and chemical potentials of strained films can be used to calculate the probability of cluster nucleation, using classical nucleation theory. 

Fig. 3.18 Schematic outline and ideal band diagram of an extremely thin absorber solar cell. The n-Ti02 crystallites are clustered together to form a relatively open, network-like morphology, accommodating a thin layer of CdTe absorber, with p-ZnTe at the back contact. (Reprinted from [270], Copyright 2009, with permission from Elsevier)...

The role played by the support of influencing the surface composition of supported bimetallic clusters has only recently begun to receive some attention. Miura, a ( ) have shown that the nature of the support can play an important role in determining not only the surface composition of the supported bimetallic clusters but also the morphology of the particles. For silica-supported Pt-Ru... 

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