Etched Structures Dependent on Sidewise Motion of 180° Domains in BaTiO 3

Sidewise motion of 180° domains in BaTiO 3 single crystals during electrical poling with a wet electrode technique results in etch pit patterns strikingly similar to dislocation patterns in other crystals. The etching behavior of the pits is also consistent with that of small 180° domains in this material. Very small inclusions are also revealed in a poled and etched crystal as small round 180° domains representing regions which could not be reversed by the electric field. It is suggested that dislocations in tetragonal BaTiO 3 , may also be revealed in this manner. The origin of the small circular 180° domains is revealed by a photomicrograph of the “hanging up” of a moving 180° domain wall as it encounters defects during sidewise motion through the crystal. Based on this photomicrograph a wall energy calculation was made for the 180’domain in a BaTiO 3 single crystal in which the sidewise motion of the wall is treated as a surface tension phenomenon. Good agreement with the accepted value of 1.4 ergs per cm 2 was obtained if a correction was made for the potential drop through the material of lower dielectric constant used in the poling process.