Effect of grain morphology and ion diffusion on the dielectric properties of ferroelectric-dielectric composite ceramics.

The relationship between microstructure, ion diffusion and dielectric properties of (1-x) (Ba_0.5Sr_0.5)_1.01TiO₃-x ZnAl₂O₄ composite ceramics were systematically studied. With the increase of ZA content, the grain morphology of composite ceramics changed dramatically, of which the grain size of (BS)_1.01T50 decreased first and then increased. The introduction of ZA diluted the ferroelectricity of (BS)_1.01T50, which reduced the permittivity of (BS)_1.01T50. When the content of ZA was 50 wt%, a high tunability of 34% was obtained. Ion diffusion and grain size affected the Curie temperature, which in turn affected the tunability. In addition, the significant changes in grain morphology weaken the connectivity between the (BS)_1.01T50 grains, thereby reducing the tunability. The variation of Q value was mainly associated with the doping effect and the composite effect. [ABSTRACT FROM AUTHOR]