The Improvement of Microwave Dielectric Properties on Al2O3 Ceramics

Al2O3 ceramics are a candidate for millimeter-wave dielectrics. It possesses a high quality factor (Q·f) and a low dielectric constant ([straight epsilon]r), however, a relatively large negative temperature coefficient of resonant frequency (τf) is an obstacle. For microwave communicating applicatio...

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Bibliographic Details
Published inFerroelectrics Vol. 387; no. 1; p. 1
Main Authors Miyauchi, Yasuharu, Kagomiya, Isao, Ohishi, Yoshihiro, Ohsato, Hitoshi
Format Journal Article
LanguageEnglish
Published Philadelphia Taylor & Francis Ltd 22.07.2009
Subjects
Ceramics
Dielectric properties
Microwave heating
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Summary:Al2O3 ceramics are a candidate for millimeter-wave dielectrics. It possesses a high quality factor (Q·f) and a low dielectric constant ([straight epsilon]r), however, a relatively large negative temperature coefficient of resonant frequency (τf) is an obstacle. For microwave communicating application, a τf value near 0 ppm/°C is desirable to keep the frequency stability at various temperatures. On the other hand τf of TiO2 is positive value, indicating that the τf can be improved by doping TiO2 in Al2O3. However 0.9Al2O3-0.1TiO2 sintered above 1350°C were composed of three phases: Al2O3, TiO2 and Al2TiO5. The τf value was about -20 -30 ppm/°C. By annealing in 1000-1100 °C, τf value approached to be 0 ppm/°C with decomposition of AlTi2O5. A good Q·f was obtained by optimizing the annealing condition. [PUBLICATION ABSTRACT]
ISSN:0015-0193
1563-5112