Effects of milling condition on the formation of core–shell structure in BaTiO3 grains

The effects of ball-milling condition on the formation of core–shell structure in BaTiO3 grains were studied. As the ball-milling time increased from 12 h to 48 h, the stress given by the milling process was accumulated in the powders while the primary powder size was reduced at 24 h milling and additional comminution of powders occurred at 48 h milling. The change of powder characteristics did not induce any difference in the sinterability but influenced on the formation of core–shell structure. The increase in milling time facilitated the shell formation leading to the increased shell portion in the core–shell grain. And at 48 h milling, the comminution effect as well as the increased milling stress resulted in the extensive formation of shell which was reflected by the remarkable rise of low temperature part of relative dielectric constant vs. temperature curve.