Catalytic oxidation of solid materials
US4526629A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 15, 1984 |
| Grant date | Jul 2, 1985 |
| Priority date | — |
| Expiry date | May 15, 2004 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S505/818
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
One or more monolayers of cerium arrayed on the surface of a niobium metal acts as a catalyst to oxidation of the niobium at ambient temperature and results in a very thin, very high quality insulating layer which may be configured by patterning of the catalyst. Significant amounts of Nb.sub.2 O.sub.5 are formed at pressures as low as 6.6.times.10.sup.-6 Pa, promoted by the presence of the cerium. This catalytic activity is related to the trivalent to tetravalent valence change of the cerium during oxidation. The kinetics of Nb.sub.2 O.sub.5 formation beneath the oxidized cerium shows two stages: PA0 the first stage is fast growth limited by ion diffusion; PA0 the second stage is slow growth limited by electron tunneling. Other catalytic rare earths usable instead of cerium are terbium and praseodymium; other substrate materials usable instead of niobium are aluminum, hafnium, silicon and tantalum, or oxidizable alloys thereof.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.