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Low Dielectric Loss Ceramics in the ZnAl 2 O 4 –TiO 2 System as a τ f Compensator
Author(s) -
Huang ChengLiang,
Yang TungJung,
Huang ChungChia
Publication year - 2009
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2008.02827.x
Subject(s) - materials science , sintering , ceramic , dielectric , microstructure , analytical chemistry (journal) , dielectric loss , microwave , mineralogy , phase (matter) , composite material , optoelectronics , chemistry , physics , organic chemistry , chromatography , quantum mechanics
The microstructure and microwave dielectric properties of a (1− x )ZnAl 2 O 4 – x TiO 2 ceramic system prepared by the mixed oxide route have been investigated. The phases of ZnAl 2 O 4 and TiO 2 co‐exist with each other and form a two‐phase system, which is confirmed by the X‐ray diffraction patterns and the energy dispersive X‐ray spectrometer analysis. The microwave dielectric properties of the specimens are strongly related to the sintering temperature, the density, and the mole ratio of ZnAl 2 O 4 /TiO 2 . The sintering temperature of the specimen can be effectively lowered by increasing the TiO 2 content. The Q u × f values of the ceramics can be significantly boosted by adding an appropriate amount of TiO 2 and by sintering at a suitable temperature. Consequently, a very high Q u × f of 277 000 GHz associated with an ɛ r of 25.2 and a large resonant frequency (τ f ) of 177 ppm/°C are obtained using 0.5ZnAl 2 O 4 –0.5TiO 2 ceramics at 1390°C/4 h. These unique properties can be utilized as a τ f compensator for dielectrics that would require extremely low loss. The MgTiO 3 and Mg 4 Nb 2 O 9 having negative τ f were mixed with 0.5ZnAl 2 O 4 –0.5TiO 2 ceramics to achieve dielectrics with a low ɛ r , a high Q u × f , and a nearly‐zero τ f . In addition, a circle dual‐mode microstrip bandpass filter is designed and fabricated using the proposed dielectric to study its performance.