Grain orientation effects on electrical properties of bismuth layer-structured ferroelectric ceramics

The grain orientation technique, which is one of several ceramic preparation methods with a controlled grain structure during the ceramic sintering process, gives an anisotropic single-crystal-like behavior to the ceramics with lower symmetric crystal structure such as the bismuth layer-structured and the tungsten bronze types than the perovskite structure. Bismuth layer-structured ferroelectrics (BLSF) are characterized by low dielectric constant, high Curie temperature and large anisotropy in electromechanical coupling factors than those of PZT family. Further more, the characteristics can be easily enhanced by the grain orientation. This paper describes the effects of grain orientation on electrical properties such as dielectric, ferroelectric, piezoelectric and pyroelectric properties of some grain-oriented BLSF ceramics by the hot-forged (HF) method, comparing them with ordinarily fired (OF) non-oriented ones.