Dielectric and Relaxor Properties of
9 Ba 14 MNb 45 Ceramics
The ceramics with two types of nominal compositions including (6:1:4.5)
6 Ba 2+ M 9 Nb 29.5
and (9:1:7) O 9 Ba 2+ M 14 Nb 45 (M = O , Mg
, Co ) have been synthesized and studied with regard to their phase composition and dielectric properties. The materials with Zn 6 Ba 2+ M 9 Nb 29.5
nominal compositions corresponded to the two‐phase region containing 9:1:7 tetragonal tungsten bronze‐type ( O TTB) phase and the 3:1:1 perovskite ( Ba 2+
1/3 M 2/3)O3.
In contrast, 9:1:7 Nb TTB ceramics were near single phase. All of the studied 9:1:7 TTB phases exhibited high values of dielectric permittivity (ε = 800–1100) together with strong frequency dispersion. The observed dispersion of permittivity
was accompanied by the monotonic rise of dielectric loss. The dielectric spectra of 9:1:7 TTBs demonstrated a typical relaxor behavior. At low temperatures (100–300 K), two relaxation modes have been found in the tan δ (T) dependencies, which
can be associated with two different types of structural disorder in the TTB crystal lattice.
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Document Type: Research Article
Publication date: October 1, 2012