Crossover of Ba(Ti,Y)O3 Solid Solutions to Ba3Ti2YO8.5–BaTiO3 Composites and their Dielectric Properties.

Ceramic samples with the nominal composition (1− x) BaTiO3+ x Ba3Ti2YO8.5 ( x=0−0.535) were prepared by the mixed oxide method. X-ray diffraction (XRD) analysis shows that the materials are of single phase with a cubic symmetry as x≤0.16. The compositions of the solid solutions ( x≤0.16) can be expressed equivalently as Ba(Ti1− yY y)O3−δ ( y≤0.122, y= x/(1+2 x)). For x>0.16, the materials are diphasic composites consisting of Ba(Ti1− yY y)O3 ( y=0.122) and Ba3Ti2YO8.5. The microstructure observation by scanning electron microscopy supports the XRD result. The dielectric behavior and phase transitions of the solid solutions ( x≤0.16) vary with different Y concentrations. The dielectric constant of the composites ( x>0.16) follows approximately the Lichteneker relation in a wide temperature range. [ABSTRACT FROM AUTHOR]