Structure dependence of ferroelectric properties of bismuth layer-structured ferroelectric single crystals

Ferroelectric properties along the a(b) axis and c axis in single crystals of various bismuth layer-structured ferroelectrics (BLSFs) were investigate d. By measuring saturated P-E hysteresis curves of BLSFs, values of the sat urated remanent polarization and the coercive electric field were found to be related to the Curie temperature and the number of BO6 octahedra (m) bet ween bismuth layers, respectively, along the a(b) axis. The saturated reman ent polarization was larger in the BLSF with a higher Curie temperature. Th is is attributed to a large atomic displacement accompanied by a high Curie temperature. In contrast, the saturated coercive electric field was smalle r in the BLSF with a larger number of in. This phenomenon is assumed to be caused by the decrease in the strain energy of the octahedra from the bismu th layer, which leads to an easy movement of the octahedral cations in the direction of an applied external electric field. Along the c axis, the BLSF s with an odd number of in had the same relationship, that is, the saturate d remanent polarization was larger with the high Curie temperature, and the saturated coercive field was smaller with the large In number. However, no remanent polarization was confirmed in the BLSFs with an even number of m. (C) 2001 American Institute of Physics.