Dynamic phenomena Electrode

Electrolytic gas evolution is a dynamic phenomenon affected by interactions among all the process variables. The interaction of the potential, electrode, and electrolyte not only determines the rate at which gas is evolved, but also affects the contact angles of the bubbles that determine, in conjunction with the electrolyte surface tension, the fundamental forces binding the bubbles to the electrode. Since the process occurs at a surface, small quantities of impurities may have a large effect. The dynamics of bubble evolution... 

In the case of dynamic random access memory (DRAM), the top electrode used in capacitor for a device s high speed raises the necessity of noble mefals like rufhenium (Ru), platinum (Pt), and iridium (Ir), which have low electric resistance and are mechanically and thermally stable. These noble metals are also chemically very stable and it is not easy to form capacitors by fhe efch back process. That is why noble metal CMP is compulsory. However, Ru is divided during the CMP process as a consequence of poor adhesion of leakage of cap oxide, grain growth of Ru, and cap oxide. To protect this phenomenon, the application of new functional slurry is essential. 

In addition, in any electrochemical component, at every interface between an electrode and the electrolyte, there is a spontaneous phenomenon of accumulation of opposite charges on both sides of that interface, which then constitutes a condenser, in the electrostatic sense of the term (Figure 1.2a). This phenomenon is referred to as a double electrochemical layer . As local electrical polarization occurs over a depth ranging from a few dozen to a few hundred nanometers around that interface, the equivalent condensers may have very large values if the electrodes have a very large surface per volume (they are therefore dubbed supercapacitors). This phenomenon plays an important role in the dynamic behavior of the component. 

ACEO is a phenomenon of induced-charge electro-osmosis (ICEO), where flow is generated by the action of an electric field on its own induced diffuse charge near a polarizable surface. The main difference with other examples of ICEO, such as flows around metal colloids, is that ACEO involves electrode surfaces, which supply both the electric field and the induced screening charge, in different regions at different times. For this reason, ACEO is inherently time-dependent (as the name inplies) and tied to the dynamics of diffuse charge, as ions move to screen the electrodes. 

The specific electrical conductivity of pure Azoxy-compounds lies between 10 (12 cm)" and 10 ( 2 cm) h Various dopants are added to the Azoxy-compound to influence the conductivity and orientation. The effect of these additives on the variation with time of the electrical conductivity, of the switching times, and of contrast can be measured. It has been found that after roughly 500 hours of operation for instance the cell conductance when measuring the d.c. current flowing through the cell decreases by one to two powers of ten. As subsequent a.c. measurements revealed, this phenomenon results from the formation of double layers with lower electrical conductivity near the electrodes. These double layers disturb the ion injection from the electrode. As a result of low current densities the dynamic scattering disappears almost entirely. 

The charge double layer is a complex and interesting electrode phenomenon, and whole books have been written on the topic (Bokins et al., 1975). However, a much briefer account will suffice in this context. The charge double layer is important in understanding the dynamic electrical behaviour of fuel cells. 

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