Transmission Electron Microscopy at Grain Boundaries of PTC‐Type BaTiO 3 Ceramics

Transmission electron microscopy of the grain boundaries of Ti‐rich semiconducting PTC‐type BaTiO 3 ceramics is described. At a width of 2 to 10 nm, there were no indications of intergranular second‐phase layers covering the grains. Second phase was segregated only at the contacts of three or more grains; electron diffraction confirmed the amorphous structure of this phase. Observed ferroelectric domains at the grain boundaries do not indicate a PTC‐specific orientation of ferroelectric domains due to the negative grain surface charge.