Geoscience Reference
In-Depth Information
Figure 3.30 The schematic diagram of
the interior of a conductance cell
[85]
.
Actual conductance cell is shown in
Figure 3.31
.
Linen-bakelite cone
Teflon
A
Pt-25% Ir screw
C
Pt-25% Ir
Al
2
O
3
insulation tube (B)
Teflon
plug
Stainless steel cone
Stainless steel
electrode holder
Furnace
Neoprene packing
ring
Figure 3.31 A conductance cell
[85]
.
Schematic diagram is shown in
Figure 3.30
.
Franck in 1956
[74]
, later it was improved greatly by Quist and Marshall during
1968
[85]
. The cell assembly is made of 61 cm long platinum—25% iridium-lined
pressure vessel with a platinum
iridium wire running from one end of the vessel
through a 30.5 cm long aluminum oxide tube to a platinum
iridium cylinder in the
center. The wire passes out of the vessel through a Bakelite (a trademark of Union
Carbide Corporation) insulator. The linings of the vessel and the small cylinder are
both electrolytically coated with “platinum black” (a mixture of fine-grained platinum
and platinum oxide), and both linings act as two electrodes
[86]
.
Hydrothermal
Electrochemical Method
The hydrothermal
electrochemical method is an attractive technique for the synthe-
sis of several complex oxide thin films, including the perovskite type. The method
makes positive use of the reaction between species included in the electrolytic
solution and the substrate being used as an electrode of the electrolytic cell under
hydrothermal conditions. For example, perovskite-type oxide, ABO
3
, has to be
synthesized on an electrode of B-site metal being oxidized anodically in an alkaline
solution containing an A-site element at lower temperatures (typically, 100
200
C)
than those needed for conventional methods. Hawkins and Roy
[87]
introduced
