450
12 Localized or Spatially Selective Electrodeposition Methods
so that no bulk deposition is initiated. The setup is hence technically somewhat problematic since the proper distance from the interface (or the immersion depth) cannot
be defined either in general or as a function of some physico-chemical parameter
of the interface. The tip diameter was reported to vary between 0.1 and 0.5 mm. In
most cases, the tip cathode was placed nearly at the centre of an anode ring for the
sake of an even field distribution [96, 99, 100]. If an anode plate was used instead of
the cylindrical arrangement, the metal growth was rather unidirectional after a short
nucleation period [97], pointing towards the anode. This clearly shows that, beside
the presence of the ITIES, the electric field has an impact on the metal layer growth.
Lateral metal growth along the ITIES was studied for Zn [99] and Cu [100].
In both cases, the deposition was carried out by applying an electrode potential at
which the layer growth is either much influenced by mass transport or pronouncedly
diffusion limited.
Zn deposition was reported to be plate-like at the beginning and then adopting a
fractal-like branched pattern, similarly to diffusion-limited aggregates [99]. Upon the
application of a magnetic field perpendicular to the ITIES, the magnetohydrodynamic
effect manifested itself by leading to a spiral fractal growth. The thickness of the zinc
layer forming was not reported. In two other papers [96, 97], the growth of the Zn
whisker at the tip was reported to be accompanied by a correlated oscillation of
the current and the meniscus, indicating a wetting/de-wetting phenomenon as the
interfacial conditions changed.
Cu deposition at ITIES was well documented [100]. The smaller was the concentration of the Cu
2+ ions and the lower was the overpotential of the deposition, the
smoother edge could be obtained and, at the same time, the upper view of the growing
plate appeared to be less and less wavy. This is presented in Fig. 12.7. Under ideal
circumstances, a nearly mirror-like upper surface was obtained as the growth front
followed the ITIES (c.f. the result obtained for electroless metal growth at the ITIES
as shown in Fig. 12.6 of Ref. [103]). The morphology of the film made it clear that
the mass transport limitation of the layer growth was approximately hemicylindrical
and planar near the penetrating edge and at the plate facing the aqueous solution,
respectively. This led to a current density ratio between 10
5 and 10
7 depending on
the deposition conditions, and the thickness of the 3-cm disc obtained was a few tens
of micrometres only. As it can be seen in Fig. 12.7d, the morphology of the two sides
of the film was clearly different. Since the plate growth took place at the bottom
side, the depleted and, hence, lower-density electrolyte solution layer was not mixed
(no gravitational instability occurred). This probably provided an ever-expanding
diffusion field throughout the deposition period, which led to a typical branching of
the deposit obtained with mass transport control. This filament-like morphology is
obvious from the cut-away SEM image of the plate produced.
In contrast to the setup applied for metal layer growth along the ITIES, the electrode configuration suitable for the dynamic three-phase interline electropolymerization (D3PIE) is quite not crucial [63–65, 90]. Since the conditions for the electropolymerization are appropriate only at the three-phase boundary line, the metal
wire can cross the interface with no strict restriction concerning its end position.
Interestingly, but apparently not necessarily, the organic phase chosen was always of
12 Localized or Spatially Selective Electrodeposition Methods
so that no bulk deposition is initiated. The setup is hence technically somewhat problematic since the proper distance from the interface (or the immersion depth) cannot
be defined either in general or as a function of some physico-chemical parameter
of the interface. The tip diameter was reported to vary between 0.1 and 0.5 mm. In
most cases, the tip cathode was placed nearly at the centre of an anode ring for the
sake of an even field distribution [96, 99, 100]. If an anode plate was used instead of
the cylindrical arrangement, the metal growth was rather unidirectional after a short
nucleation period [97], pointing towards the anode. This clearly shows that, beside
the presence of the ITIES, the electric field has an impact on the metal layer growth.
Lateral metal growth along the ITIES was studied for Zn [99] and Cu [100].
In both cases, the deposition was carried out by applying an electrode potential at
which the layer growth is either much influenced by mass transport or pronouncedly
diffusion limited.
Zn deposition was reported to be plate-like at the beginning and then adopting a
fractal-like branched pattern, similarly to diffusion-limited aggregates [99]. Upon the
application of a magnetic field perpendicular to the ITIES, the magnetohydrodynamic
effect manifested itself by leading to a spiral fractal growth. The thickness of the zinc
layer forming was not reported. In two other papers [96, 97], the growth of the Zn
whisker at the tip was reported to be accompanied by a correlated oscillation of
the current and the meniscus, indicating a wetting/de-wetting phenomenon as the
interfacial conditions changed.
Cu deposition at ITIES was well documented [100]. The smaller was the concentration of the Cu
2+ ions and the lower was the overpotential of the deposition, the
smoother edge could be obtained and, at the same time, the upper view of the growing
plate appeared to be less and less wavy. This is presented in Fig. 12.7. Under ideal
circumstances, a nearly mirror-like upper surface was obtained as the growth front
followed the ITIES (c.f. the result obtained for electroless metal growth at the ITIES
as shown in Fig. 12.6 of Ref. [103]). The morphology of the film made it clear that
the mass transport limitation of the layer growth was approximately hemicylindrical
and planar near the penetrating edge and at the plate facing the aqueous solution,
respectively. This led to a current density ratio between 10
5 and 10
7 depending on
the deposition conditions, and the thickness of the 3-cm disc obtained was a few tens
of micrometres only. As it can be seen in Fig. 12.7d, the morphology of the two sides
of the film was clearly different. Since the plate growth took place at the bottom
side, the depleted and, hence, lower-density electrolyte solution layer was not mixed
(no gravitational instability occurred). This probably provided an ever-expanding
diffusion field throughout the deposition period, which led to a typical branching of
the deposit obtained with mass transport control. This filament-like morphology is
obvious from the cut-away SEM image of the plate produced.
In contrast to the setup applied for metal layer growth along the ITIES, the electrode configuration suitable for the dynamic three-phase interline electropolymerization (D3PIE) is quite not crucial [63–65, 90]. Since the conditions for the electropolymerization are appropriate only at the three-phase boundary line, the metal
wire can cross the interface with no strict restriction concerning its end position.
Interestingly, but apparently not necessarily, the organic phase chosen was always of