Electron microscopy and surface analysis of niobia-silica surface oxides using model thin films

Thesis/Dissertation · Thu Jan 01 04:00:00 EST 1987

OSTI ID:6408142

Weissman, J G

Model thin films, corresponding to 1, 3, and 12 monolayers of niobia, deposited by RF-sputtering onto silica, were prepared to study the interactions between surface phase and supporting oxides. These samples were treated in air at 500 and 600/sup 0/C for up to 16 hours and then observed using AES, XPS, TEM, and HREM. Nb/sub 2/O/sub 5/ in reactively-sputtered films crystallized to T- and/or H-Nb/sub 2/O/sub 5/ after heating. Nb/sub 2/O/sub 5/-SiO/sub 2/ high-surface-area samples similarly treated, however, exhibited a strong interaction that resulted in the stabilization of surface-phase Nb/sub 2/O/sub 5/ at monolayer coverage and formation of T-Nb/sub 2/O/sub 5/ at higher loadings. The difference between the thin-film and high-surface-area samples was understood in terms of stabilization of surface niobia due to surface hydroxyl groups. These results illustrate the applicability of model thin films in studying surface oxides, and examples are presented relating the model for oxide behavior developed here to other systems in the literature.

• Research Organization: Carnegie-Mellon Univ., Pittsburgh, PA (USA)
• OSTI ID: 6408142
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
CHALCOGENIDES
DEPOSITION
FILMS
HEAT TREATMENTS
HIGH TEMPERATURE
NIOBIUM COMPOUNDS
NIOBIUM OXIDES
OXIDES
OXYGEN COMPOUNDS
REFRACTORY METAL COMPOUNDS
SILICON COMPOUNDS
SILICON OXIDES
SPUTTERING
SUBSTRATES
SURFACES
THIN FILMS
TRANSITION ELEMENT COMPOUNDS