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Fabrication of a High Permittivity Ceramic Capacitor in a Reducing Atmosphere

IP.com Disclosure Number: IPCOM000094988D
Original Publication Date: 1965-Aug-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Delaney, RA: AUTHOR [+3]

Abstract

Since air has a dielectric constant of approximately unity, the porosity in a layer of dielectric material such as barium titanate tends to reduce its dielectric constant. One manner in which such porosity can be removed is that of reducing the barium titanate body.

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Fabrication of a High Permittivity Ceramic Capacitor in a Reducing Atmosphere

Since air has a dielectric constant of approximately unity, the porosity in a layer of dielectric material such as barium titanate tends to reduce its dielectric constant. One manner in which such porosity can be removed is that of reducing the barium titanate body.

Such is effected either with or without a bismuth oxide binder by firing in forming gas (90%N(2), 10%H(2)). Then, the material is screened and fired in an oxidizing atmosphere to increase the volume of the barium titanate body. This increase in volume results in a denser layer with reduction of porosity in the layer.

When capacitors are formed with such a reduced dielectric layer for reasonably short firing times, the top capacitor plate prevents the reduced dielectric layer from re-oxidizing. This characteristic results in a high DC resistance. The material nevertheless is very lossy at high frequencies with good damping characteristics in addition to a desirable high capacitance. While such a system may not be as advantageous as other systems for low voltage biases, this particular dielectric layer can be used under biases of up to 50 volts DC.

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