Licensable Technology
Inventions Resulting from Penn State Energy Research
Low Temperature Sintering of Antiferroelectric Lead-based Ceramics
By J.P. Dougherty, et al.
Penn State Invention Disclosure No. 1682
Field of Invention
Materials Sciences
Background of the Invention
A class of nonlinear, antipolar ceramic materials, termed antiferroelectrics, exhibit increasing dielectric constants as an applied electric field is increased. At a certain applied electric field, an antiferroelectric undergoes a phase transition to a ferroelectric phase (exhibiting a polar characteristic) and the dielectric constant goes through a large increase at this electric field induced phase transition. In the ferroelectric phase the dielectric constant shows the normal decrease in dielectric constant at higher voltages. Prior research indicates that improved energy storage can be achieved in a capacitor employing antiferroelectric dielectric layers by applying an electric field across the dielectric layers which enables a transition thereof through both an antiferroelectric phase and plural ferroelectric phases. For capacitors which employ such antiferroelectric ceramics, there is a need to achieve cost savings in their production by use of less expensive contact electrodes.
Description of Invention
This invention relates to the production of antiferroelectric, lead-based ceramics and capacitors made from such ceramics by a method which enables sintering of such ceramics at temperatures of about 1100 oC or below. The dielectric properties of the sintered material showed no degradation and achieved approximately equal energy storage values, for equivalent applied electric fields. The process can be tailored to specific requirements by varying the compounds used.
Patent Status
U.S. Patent No. 6,993,895 has been issued for this technology. Related patents include U.S. Patent Nos. 5,728,138 and 5,545,184.
Utility
A lower sintering temperature allows for greater control of the lead loss characteristics of these materials. This permits more reliable manufacturing. The lower sintering temperature allows the use of Pd-Ag electrodes instead of Pt. This reduces the cost of making multilayer capacitors from antiferroelectric PLZT materials.
Contact
Matthew D. Smith
Intellectual Property Office
mds126@psu.edu