Method for Low Temperature Production of Nano-Structured Iron Oxide Coatings

Abstract

The present invention provides a method for forming nano-structured iron oxide coatings on a substrate. The method includes the steps of: (a) subjecting a chamber containing a plasma source to vacuum; (b) feeding iron pentacarbonyl and O2 into a chamber containing a plasma source, wherein the O2 is fed into the chamber at a rate greater than that of the iron pentacarbonyl; (c) subjecting the substrate to the chamber, wherein the substrate is at a temperature less than 250° C., thereby forming an iron oxide coating on the substrate, wherein the iron oxide is greater than 90 percent in the α-hematite form.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority to U.S. Provisional Patent Application Ser. No. 60 / 778,729 filed on Mar. 2, 2006, U.S. Provisional Patent Application Ser. No. 60 / 778,730 filed on Mar. 2, 2006 and U.S. Provisional Patent Application Ser. No. 60 / 811,403 filed on Jun. 5, 2006 the entire disclosures of which are incorporated by reference.FIELD OF THE INVENTION [0002] The present invention provides a method for forming nano-structured iron oxide coatings on a substrate. BACKGROUND OF THE INVENTION [0003] Several techniques are known for depositing iron oxide coatings onto a substrate. Most of the methods, however, are limited in that substrate temperatures greater than 400° C. are used. This is because the oxides are pyrolytically formed on the substrate surface. Such procedures inherently limit the types of substrates that may be used, since substrates melting at the high temperatures are prohibited. [0004] It is accordingly an object of t...

AI Technical Summary

Benefits of technology

[0010] Iron pentacarbonyl and O2 are fed into a chamber, containing a plasma source, through two separate feed lines. The O2 is fed in at a rate at least 4 times greater than that of the iron pentacarbonyl. The chamber is subjected to vacuum prior to deposition and maintained under vacuum throughout the procedure. A substrate is subjected to the chamber, resulting in the production of an iron oxide coating on the substrate. During the deposition, the substrate is at a temperature less than 250° C.

[0011] The plasma source is typically a high density plasma source, and it is oftentimes an argon plasma source. In certain cases, O2 is fed into the chamber at a rate at least 8 times greater than that of the iron pentacarbonyl, and oftentimes it is fed at a rate at least 12 times greater. The chamber is typically subjected to a vacuum of at least 0.10 torr, and, in some cases, to a vacuum of at least 0.01 torr or even 0.005 torr. Substrates may be of any suitable composition. Nonlimiting examples include a spectrally transparent cyclic-olefin copolymer, pure poly(norbomene), and a conducting glass plate having an F-doped SnO2 overlayer. The substrate temperature during the deposition is usually less than 200° C. In certain cases it may be less than 175° C., 150° C., or 125° C.

Problems solved by technology

Most of the methods, however, are limited in that substrate temperatures greater than 400° C. are used.

Such procedures inherently limit the types of substrates that may be used, since substrates melting at the high temperatures are prohibited.