Influences of Excess Bi2O3 and K2CO3 on Crystal Structure, Microstructure and Dielectric Properties of Bismuth Potassium Titanate Ceramics

Abstract

Bismuth potassium titanate [(Bi0.5K0.5)TiO3; BKT] ceramics were fabricated by the solid state reaction method using calcination and sintering temperatures of 800°C and 1030°C. To prevent Bi2O3 and K2CO3 evaporation during the firing process, excess Bi2O3 and K2CO3 in the ratio of 1:1 were added to the samples in varying amounts from 0–10 mol%. The XRD results of all samples were indexed in a tetragonal structure. The lattice parameters a, c and the c/a ratio tended to decrease with increasing excess Bi2O3 and K2CO3. The average particle size increased while the average grain size decreased with increasing amounts of Bi2O3 and K2CO3. The porous microstructure slightly decreased with an increasing amount of Bi2O3 and K2CO3, up to 1 wt.%, and then slightly increased with higher amount of excess Bi2O3 and K2CO3. The density (ρ = 5.75 g/cm3), dielectric constant (ϵ r = 5,584) and dielectric loss (tanδ = 0.76) can be improved by adding 1 wt.% of excess Bi2O3 and K2CO3.