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Dielectric composite materials and method for preparing

United States Patent

July 29, 2003
View the Complete Patent at the US Patent & Trademark Office
Oak Ridge National Laboratory - Visit the Partnerships Directorate Website
The invention allows the fabrication of small, dense beads of dielectric materials with selected compositions, which are incorporated into a polymeric matrix for use in capacitors, filters, and the like. A porous, generally spherical bead of hydrous metal oxide containing titanium or zirconium is made by a sol-gel process to form a substantially rigid bead having a generally fine crystallite size and correspondingly finely distributed internal porosity. The resulting gel bead may be washed and hydrothermally reacted with a soluble alkaline earth salt (typically Ba or Sr) at elevated temperature and pressure to convert the bead into a mixed hydrous titanium- or zirconium-alkaline earth oxide while retaining the generally spherical shape. Alternatively, the gel bead may be made by coprecipitation. This mixed oxide bead is then washed, dried and calcined to produce the desired (BaTiO.sub.3, PbTiO.sub.3, SrZrO.sub.3) structure. The sintered beads are incorporated into a selected polymer matrix. The resulting dielectric composite material may be electrically "poled" if desired.
Lauf; Robert J. (Oak Ridge, TN), Anderson; Kimberly K. (Knoxville, TN), Montgomery; Frederick C. (Oak Ridge, TN), Collins; Jack L. (Knoxville, TN), Felten; John J. (Chapel Hill, NC)
UT-Battelle, LLC (Oak Ridge, TN), E. I. Dupont de Nemours and Company (Wilmington, DE)
10/ 256,843
September 27, 2002
The invention was made with government support under contract no. DE-AC05-00OR22725 awarded by the United States Department of Energy to Lockheed Martin Energy Research Corporation; and the government has certain rights in the invention.