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High-Temperature Dielectric Properties of Polycrystalline Ceramics

Published online by Cambridge University Press:  21 February 2011

W. W. Ho
W. W. Ho*
Affiliation:
Rockwell International Science Center, 1049 Camino Dos Rios, Thousand Oaks, CA 91360
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Abstract

Experimental methods for determining the high-temperature millimeter-wave dielectric properties of solids are described and the data obtained on a wide variety of polycrystalline ceramics are reviewed. In general, the observed increase in dielectric constants with temperature can be modeled with a macroscopic dielectric virial expansion and shown to be primarily caused by an increase in polarizability due to volume expansion. The room-temperature loss tangents in low-absorption ceramics are probably caused by impurity doping of the primary and secondary crystalline phases at grain junctions and along grain boundaries. The rapid increase in loss tangent at high temperatures commonly observed in polycrystalline ceramics is associated with softening of intergranular amorphous phases resulting in an increase in localized electrical conductivity.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 124: Symposium M – Microwave Processing of Materials I , 1988 , 137
Copyright
Copyright © Materials Research Society 1988

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References

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