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Microwave Dielectric Properties and Low‐Temperature Sintering of (1− x )CeO 2 − x BaTi 4 O 9 Ceramics
Author(s) -
Anjana Prabhakaran Sreekumari,
Sebastian Mailadil Thomas
Publication year - 2008
Publication title -
international journal of applied ceramic technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.4
H-Index - 57
eISSN - 1744-7402
pISSN - 1546-542X
DOI - 10.1111/j.1744-7402.2008.02195.x
Subject(s) - materials science , temperature coefficient , analytical chemistry (journal) , ceramic , sintering , dielectric , microstructure , scanning electron microscope , atmospheric temperature range , relative permittivity , relative density , mineralogy , microwave , permittivity , composite material , thermodynamics , chemistry , optoelectronics , physics , chromatography , quantum mechanics
(1− x )CeO 2 − x BaTi 4 O 9 ceramics were prepared by the solid‐state ceramic route. The structure and microstructure of the ceramics were studied using X‐ray diffraction (XRD) and scanning electron microscope. XRD patterns indicate that (1− x ) CeO 2 − x BaTi 4 O 9 ceramics were of a two‐phase composite consisting of fluorite CeO 2 and BaTi 4 O 9 . The microwave dielectric properties such as relative permittivity (ɛ r ), quality factor ( Q u × f ), and coefficient of temperature variation of resonant frequency (τ f ) of the ceramics have been measured in the frequency range 4–6 GHz by the resonance method. The 0.5CeO 2 –0.5BaTi 4 O 9 samples sintered at 1260°C/2 h exhibit excellent microwave dielectric properties: ɛ r =34.5, Q u × f =20,750 GHz (at 4.2 GHz) and τ f =1.8 ppm/°C. The density, dielectric constant, and temperature coefficient of resonant frequency of mixtures predicted by the appropriate mixing relations agree well with the experimental values. The addition of B 2 O 3 and CuO significantly lowered the sintering temperature of 0.5CeO 2 –0.5BaTi 4 O 9 ceramic to 950°C. The 0.5CeO 2 –0.5BaTi 4 O 9 +12 wt% B 2 O 3 +1 wt% CuO sintered at 950°C for 4 h showed ɛ r =20.6, Q u × f =17,000 GHz (at 5.7 GHz) and τ f =+48 ppm/°C.