A HIGH-RESOLUTION TEM STUDY OF THE ANNEALING OF PD PARTICLES SUPPORTED ON MGO

Citation
S. Giorgio et al., A HIGH-RESOLUTION TEM STUDY OF THE ANNEALING OF PD PARTICLES SUPPORTED ON MGO, Journal of catalysis, 148(2), 1994, pp. 534-539
Citations number
30
Categorie Soggetti
Chemistry Physical
Journal title
ISSN journal
00219517
Volume
148
Issue
2
Year of publication
1994
Pages
534 - 539
Database
ISI
SICI code
0021-9517(1994)148:2<534:AHTSOT>2.0.ZU;2-F
Abstract
Pd clusters (4-5 nm) epitaxially grown on clean surfaces of MgO microc ubes were annealed at 450-degrees-C in pure O2 or H-2 at pressures of 10(-7) and 10(-1) Torr. The samples were investigated by high-resoluti on transmission electron microscopy in order to image both the profile view and the interface Pd/MgO. Particles annealed in oxygen at 10(-7) Torr develop a slightly rounded shape. Their lattice parameter is exp anded by 2%, as in the case of the same clusters annealed in vacuum. A nnealing under a higher pressure of oxygen induces a full rounded shap e and produces PdO on the surface and edges of the Pd particles. Parti cles annealed in H-2 retain the shape of a half-octahedron truncated a t the top by (100) faces and their lattice parameter is dilated by 3-4 %. (C) 1994 Academic Press, Inc.