Dielectric property measurements of ZrO{sub 2}-strengthened Al{sub 2}O{sub 3}

Journal Article · Tue Apr 01 04:00:00 EST 1997 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.364158· OSTI ID:527836

Link, G ^[1]; Heidinger, R ^[2]

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1. Association FZK--EURATOM, Forschungszentrum Karlsruhe, Institut fuer Technische Physik, Postfach 3640, D-76021 Karlsruhe (Germany)
2. Association FZK--EURATOM, Forschungszentrum Karlsruhe, Institut fuer Materialforschung, Postfach 3640, D-76021 Karlsruhe (Germany)

Ceramic composites of alumina and zirconia with ZrO{sub 2} contents up to 20 wt{percent} and negligible porosity were investigated at radio frequencies from 10{sup 4} to 10{sup 7} Hz, and in a temperature range from 20 to 550{degree}C. If unstabilized or partially stabilized ZrO{sub 2} is dispersed in pure alumina in order to improve the mechanical strength the dielectric properties are changed. The admixture of zirconia leads to enhanced dielectric losses and an increased temperature dependence of the permittivity. It is demonstrated that it is essential to distinguish between the contributions of the monoclinic and the tetragonal phase of zirconia. The presence of the tetragonal ZrO{sub 2} phase is correlated with the appearance of two peaks in the temperature dependence of the dielectric loss and two smoothed steps in the temperature dependence of the permittivity. This is well described by a Debye model for dipole relaxation. The presence of the monoclinic phase leads to a higher exponential temperature rise for the dielectric loss as well as for the permittivity, due to an increased ionic conductivity. At higher frequencies the influence of ionic conductivity is smaller and the dipole relaxation processes are shifted to higher temperatures. Therefore, for high-frequency applications low-loss composites with improved mechanical properties can be realized if monoclinic zirconia is kept at low levels. {copyright} {ital 1997 American Institute of Physics.}

• OSTI ID: 527836
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 7 Vol. 81; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM OXIDES
CERAMICS
COMPOSITE MATERIALS
DIELECTRIC PROPERTIES
FREQUENCY DEPENDENCE
IONIC CONDUCTIVITY
MECHANICAL PROPERTIES
PERMITTIVITY
PHASE STUDIES
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE RANGE 0400-1000 K
ZIRCONIUM OXIDES