Dielectric properties of La3+ substituted BaBi8Ti7O27 ceramics

Modification of BaBi8Ti7O27 ceramics was investigated by La substitution for Bi, and the dielectric properties were determined together with the microstructures. Ba(Bi1−xLax)8Ti7O27 solid solution was observed for x≤0.25, and Ba(Bi,La)2Ti4O12 secondary phase appeared for x>0.25. The dielectric constant, the dielectric loss and the temperature coefficient of dielectric constant increased first and reached their maximums at x=0.15 then decreased together. Ceramics with good dielectric properties: ε=102, tan δ=0.0006 and τε=−152 ppm/°C at 1 MHz were obtained at x=0.5 where the ceramics were not single phase.