Metals and Ceramics Division - Oak Ridge National Laboratory

COUNTS
900
O
Mg
Al Area A
0
0 2 4 keV 6 8 10
1200
COUNTS
0
O
Mg
Al
Pt
1500
COUNTS
Ba
0
O
Ce
Zr
Al
0 2 4 keV 6 8 10
Ce
Ce
Ce
Area B
0 2 4 keV 6 8 10
Area C
Fig. 5 EDS spectra showing A) alumina-magnesia composition of finegrained
phase in Fig. 4; B) ceria-zirconia composition of coarse-grained
phase; C) alumina-baria composition of medium-grained phase.
electron microprobe, the alumina phase is the dark-grey phase, the alumina-baria
phase is the medium-grey phase, and the ceria-zirconia phase is the phase in brightest
contrast.
The catalytically active phase in the Umicore sample was determined to be primarily Pt,
as indicated by the EDS spectrum of Fig. 6, a long acquisition time from an area of the
alumina phase. However, it was difficult to determine from BF TEM images exactly the
size and distribution of the Pt particles/clusters, so the Umicore sample was examined
using the new JEOL 2200FS-AC aberration-corrected electron microscope (ACEM).
Figure 7 is an annular dark-field image of an area of baria-alumina and alumina phases
200
COUNTS
0
O
Ce
Mg
0 2 4 keV 6 8 10
Pt
Al Area E
Pt
Ce
Ce
Ce
Fig. 6 EDS spectrum from alumina phase shown on expanded
vertical scale to show presence of Pt catalytic species.
Pt