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VO.sub.2 precipitates for self-protected optical surfaces

United States Patent

5,885,665
March 23, 1999
View the Complete Patent at the US Patent & Trademark Office
Oak Ridge National Laboratory - Visit the Partnerships Directorate Website
A method for forming crystallographically coherent precipitates of vanadium dioxide in the near-surface region of sapphire and the resulting product is disclosed. Ions of vanadium and oxygen are stoichiometrically implanted into a sapphire substrate (Al.sub.2 O.sub.3), and subsequently annealed to form vanadium dioxide precipitates in the substrate. The embedded VO.sub.2 precipitates, which are three-dimensionally oriented with respect to the crystal axes of the Al.sub.2 O.sub.3 host lattice, undergo a first-order monoclinic-to-tetragonal (and also semiconducting-to-metallic) phase transition at .about.77.degree. C. This transformation is accompanied by a significant variation in the optical transmission of the implanted region and results in the formation of an optically active, thermally "switchable" surface region on Al.sub.2 O.sub.3.
Gea; Laurence A. (Knoxville, TN), Boatner; Lynn A. (Oak Ridge, TN)
The United States of America as represented by the United States Department of Energy (Washington, DC)
08/ 853,947
May 9, 1997
GOVERNMENT SUPPORT This invention was made with government support under contract number DE-AC05-96OR22464 awarded by the Department of Energy. The government may have certain rights in this invention.