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Influence of Non‐Stoichiometry on the Structure and Properties of Ba(Zn 1/3 Nb 2/3 )O 3 Microwave Dielectrics. IV. Tuning τ f and the Part Size Dependence of Q × f
Author(s) -
Wu Hui,
Davies Peter K.
Publication year - 2006
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.1551-2916.2006.01010.x
Subject(s) - stoichiometry , sintering , annealing (glass) , solid solution , materials science , analytical chemistry (journal) , pellets , dielectric , ceramic , kinetics , crystallography , mineralogy , chemistry , metallurgy , composite material , optoelectronics , chromatography , quantum mechanics , physics
High Q ceramics of Ba 3 W 2 O 9 (BW)‐substituted Ba(Zn 1/3 Nb 2/3 ) O 3 (BZN) were prepared with a zero τ f through the partial substitution of Zn by Ni and Co. The small concentrations of B‐site vacancies introduced by the substitution of BW accelerated the kinetics and stability of the cation ordering and lowered the sintering temperature. Dense, zero τ f , ordered solid solutions such as 0.99Ba(Zn 0.3 Co 0.7 ) 1/3 Nb 2/3 O 3 –0.01BW with ɛ r =34.4 and Q × f =82 000 at ∼8 GHz could be obtained after sintering at 1380°C for 5 h and annealing at 1300°C for 24 h. Partially ordered ceramics in the Zn/Co and Zn/Ni solid solutions show a large gradient in the ordering throughout the pellets, which produces a resonant frequency dependence of their Q × f value. The ordering gradient is associated with the increased constraints on the growth of the 1:2 ordered structure within the interior of larger and thicker pellets and can be minimized by extended annealing.