Biomedical Engineering Reference
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are epitaxied on the substrate. With the extractive replica technique, there is
no way to investigate this interactivity since the substrate has to be dissolved
(Fig.
8.3)
.
2.1.2 Crushing Technique (“Techniques” Chapter 4, Section
1)
and Extractive
Replica Technique (“Techniques” Chapter 5, Section
3)
Fine particle material: 0.2% platinum catalyst particles on aluminum oxide
(Al
2
O
3
), treated with H
2
at 973 K
Comparison discussion
: the crushing technique enables keeping the substrate
together with the material. The platinum particle appears in black (high atomic
number) and allows measurements and characterizations in nanodiffraction mode.
The images of platinum in HRTEM do not have good resolution because the thick-
ness of the platinum/substrate is too high. With the extractive replica technique,
the substrate is dissolved and HRTEM observations are both possible and generally
of good quality. Measurements of platinum particle size as well as characteriza-
tions in nanodiffraction mode can also be made. In this case, good resolution can
easily be obtained in HRTEM images, since the substrate is removed (Figs.
8.4
and
8.5)
.
Fig. 8.4
Pt catalyst on
aluminum oxide Pt/Al
2
O
3
.
Thin slice obtained using the
crushing technique.
(
R. Touroude,
LMPC-ECPM-ULP
Strasbourg
)
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