Metal growth kinetics

Regnlar arrays of platinnm were achieved by chemical reduction of a platinnm salt that had been deposited onto the S-layer of Sporosarcina ureae [132]. This S-layer exhibits sqnare lattice symmetry with a lattice constant of 13.2 nm. Transmission electron microscopy revealed the formation of well-separated metal clusters with an average diameter of 1.9 nm. Seven clnster sites per nnit cell were observed. UV-VIS spectrometry was nsed to study the growth kinetics of the clnsters. 

Monitoring the Growth Kinetics of Supported Metal Catalysts... 

Supported model catalysts are frequently prepared by thermally evaporating metal atoms onto a planar oxide surface in UHV. The morphology and growth of supported metal clusters depend on a number of factors such as substrate morphology, the deposition rate, and the surface temperature. For a controlled synthesis of supported model catalysts, it is necessary to monitor the growth kinetics of supported metal... 

Metal oxidation is a heterogeneous solid state reaction and starts in the same way as other heterogeneous reactions with nucleation and initial growth. This was discussed in Chapter 6. A time-dependent nucleation rate may dominate the overall growth kinetics of thin Films. Even under an optical microscope (i.e., in macroscopic dimensions), preferential sites of growth can still be discerned [J. Benard (1971)). This indicates that lateral transport on the surface (e.g., at sites where screw dislocations emerge) can possibly be more important for the initial reactive growth than transport across thin oxide layers. 

S.D. Peteves and R. Abbaschian. Growth-kinetics of solid-liquid Ga interfaces. 1. Experimental. Metall. TYans. A, 22(6) 1259—1270, 1991. 

In the oxidation of metals, paralinear growth kinetics of oxide layers are known to be a quite usual phenomenon. Such a dependence is observed much less frequently with metallic systems due to three reasons. Firstly, the duration of investigations of the process of oxidation of metals is far longer than that in examining the solid-state interaction of two metals. Secondly, the minimal measurable thickness (or mass) of compound layers which can be detected using available techniques is in the former case much less than in the latter. Thirdly, since this anomalous dependence has no satisfactory explanation from a diffusional viewpoint, experimentalists investigating metallic systems probably prefer not to accentuate on it. 

When studying the growth kinetics of the intermetallic layers, after the run the crucible, together with the flux, the melt and the solid specimen, was shot into cold water to arrest the reactions at the transition metal-aluminium interface. Note that the solid specimen continued to rotate until solidification of the melt, ft is especially essential in examining the formation of the intermetallic layers under conditions of their simultaneous dissolution in the liquid phase (with undersaturated aluminium melts). The time of cooling the experimental cell from the experimental temperature down to room temperature did not exceed 2 s. 

Growth kinetics of intermetallic layers at the transition metal-liquid aluminium interface... 

L.N. Paritskaya, Yu.S. Kaganovskiy, V.V. Bogdanov. Kinetics and mechanisms of inter-metallic growth by bulk and surface interdiffusion // Metallofiz.Noveish.Tekhnol.-1999.- V.21, No.2.- P.26-34. 

This completes our development of the thick-film parabolic growth law. This particular theory has been presented in some detail because it is an extremely important domain of metal oxidation. In addition, it provides an excellent example of the way the coupled-currents approach [10,11] can be used to obtain oxide growth kinetics and built-in voltages in thermal oxidation. 

See also crystallization overpotential (polarization), - nucleation and growth kinetics, - equilibrium forms of crystals and droplets, - half-crystal position, - Kaischew, - metal deposition, - supersaturation, - Stranski, - Zeldovich. 

Nucleation and growth kinetics — Nucleation-and-growth is the principal mechanism of phase transformation in electrochemical systems, widely seen in gas evolution, metal deposition, anodic film formation reactions, and polymer film deposition, etc. It is also seen in solid-state phase transformations (e.g., battery materials). It is characterized by the complex coupling of two processes (nucleation and phase growth of the new phase, typically a crystal), and may also involve a third process (diffusion) at high rates of reaction. In the absence of diffusion, the observed electric current due to the nucleation and growth of a large number of independent crystals is [i]... 

If we assume, for the aluminum deposited onto polymer, similar growth kinetics as we have described above, we can think that when the interaction between the metal and the polymer becomes more reactive, the adhesion which is correlated to the number of free bonds given by the polymer, will increase and the grain size will decrease. This interpretation enables us to understand the adhesion behaviour observed when the crystallinity of the skin increase or when the skin of the polymer has been changed during a corona treatment. 

While steady-state radiolysis of metal ions solutions is a powerful method to generate small and monodisperse metal clusters and to synthesize metal nano-objects with controlled size, shape and struc-ture, pulse radiolysis technique enables to follow, in particular by time-resolved spectroscopy, the nucleation steps and the growth kinetics of the nanoparticles. ... 

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