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Effects of Postdensification Annealing on Microwave Dielectric Properties of Ba([Mg 1− x Co x ] 1/3 Nb 2/3 )O 3 Ceramics
Author(s) -
Sun Tu Lai,
Li Lei,
Mao Min Min,
Chen Xiang Ming
Publication year - 2013
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/ijac.12126
Subject(s) - annealing (glass) , materials science , dielectric , analytical chemistry (journal) , microwave , temperature coefficient , ceramic , metallurgy , composite material , physics , optoelectronics , chemistry , chromatography , quantum mechanics
Effects of postdensification annealing on microwave dielectric properties of Ba([ M g 1− x C o x ] 1/3 Nb 2/3 )O 3 ceramics have been investigated. The 1:2 ordered complex perovskite structure is obtained in the entire composition range of the as‐sintered samples, and the ordering degree decreases with increasing x . With increasing x , the dielectric constant (ε r ) increases, the temperature coefficient of resonant frequency (τ f ) shifts toward negative and can be tuned to near‐zero for x = 0.6, while the Q × f value decreases. With postdensification annealing at 1400°C in air for 24 h, the ordering degree increases, and Q × f value can be significantly improved without obvious change in ε r , while the composition for obtaining near‐zero τ f shifts to x = 0.8. Annealing at 1375°C and 1425°C in air for 24 h does not improve microwave dielectric properties more than annealing at 1400°C. A good combination of microwave dielectric properties of Ba([Mg 1− x Co x ] 1/3 Nb 2/3 )O 3 ceramics after postdensification annealing at 1400°C in air for 24 h has been obtained for x = 0.8: ε r = 31.7, Q × f = 76,900 GHz, τ f = 3.3 ppm/°C.