Deposit morphology

Deposits containing carbonate can be protective. The carbonate buffers acidity caused by the segregation of potentially acidic anions in and beneath deposits. However, deposits are rarely composed of only a single chemical mixed deposits are the rule. Deposit morphology also influences attack. Hence, although sometimes carbonate deposits are beneficial, they may also be deleterious. 

Figure 1 shows a typical lithium deposition morphology. Here, the lithium is deposited on stainless steel at 3 mA cm 2 for 1 h with 1.5 mol L1 LiAsF6 -EC/2MeTHF (1 1, v/v). 

Sulfur is known to be easily reducible in nonaqueous solvents and its reduction products exist at various levels of reduction of polysulfide radical anions (S . ) and dianions (Sm2 ) 173], Recently Be-senhard and co-workers [74] have examined the effect of the addition of polysulfide to LiC104-PC. Lithium is cycled on an Ni substrate with Qc=2.7 C cm 2 and cycling currents of 1 mA cm. The cycling efficiency in PC with polysulfide is higher than that without an additive. The lithium deposition morphology is compact and smooth in PC with added polysulfide, whereas it is dendritic in PC alone. 

These compounds may reduce the reactivity of lithium and make the lithium deposition morphology smoother as a result of the spontaneous electrochemical alloy formation during the charging of lithium on the anode. The lithium was plated on... 

Deposit morphology is very important in determining the origins of mineral deposition. The analysis of the deposit may reflect a chain of cause-and-effect problems, and these problems may stem from any of several points within the steam-cycle system. 

A combination of thermodynamic analysis and experimental data on the deposition rates, efficiencies and deposit morphologies as a function of CVD variables may be used to develop models for the deposition processes. In the case of CVD of borides such a predictive model has been created so far only for a CVD system in which TiBj is obtained by reduction of TiCl4 and BCI3 with... 

Significant improvements in ECALE deposit morphology and quality were reported as achieved by switching from a thin layer cell to a thick layer H-form cell, integrated in an automated deposition system [46]. Thin epitaxial films of zinc blende CdTe, CdSe, and CdS with predominate (111) orientations were grown. 

Cathode deposit morphology can also be affected by the presence of trace elements in solution. An SEM micrograph of a zinc deposit from a pure or unadulterated electrolyte and time duration of two minutes at 10 mA/cm2 is shown in Figure 3. When U0 parts per billion of antimony was added to this solution, and a similar electrodeposition cycle was performed, an approximate ten-fold increase in crystallite size was obtained (see Figure U). 

The potential used to deposit Cd in the formation of CdTe is an important factor in determining deposit morphology and composition. Figure... 

In [61], the influence of the nickel(II) concentration on the deposition process, in [62], the influence of potential on deposit morphology, while in [63], the morphology and structure of nickel nuclei as a function of the conditions of electrodeposition were studied. In the latter, the effects of growth rate (affected by the temperature and/or the nickel concentration), bath composition, and deposition time (particularly at low overpotentials) on the morphology of nickel nuclei were analyzed. 

The kinetics of zinc deposition on Zn electrode from a concentrated ZnC T KCl electrolyte containing commercial long-chain polymer additives was investigated using impedance spectroscopy [218]. The additive modifies the deposit morphology by changing some specific rates of the electrode reaction surface steps (see Fig. 7). 

Traditionally, glues [362, 381-383] and arable gum [384] were used as organic additives in the electrowinning of zinc. Hosny [385] and Karavasteva et al. [386, 387] used surfactants to improve the deposit morphology and current efficiency. 

One explanation for the change in deposit morphology with time observed by Sun and others [105-108] could be the structure of the double layer during deposition. 

To develop practical plating systems information about the long term stability of the ionic liquids under high applied current densities needs to be determined. The efFect of adsorbed moisture on deposit morphology also needs to be ascertained as practical liquids will have to be as robust as possible. 

Impurities are a lot less problematic for eutectic-based ionic liquids. The strong acid-base nature of these systems leads to predominantly halometallate species which tend to be unaffected by simple salts or other impurities such as water. The strong Lewis acids and bases coordinate well to water and even in the chloroa-luminate systems low amounts of water do not significantly affect voltammetric behavior or have a deleterious effect on deposit morphology. 

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