Electrical Properties of a Bismuth Layer‐Structured Ba 2 Bi 4 Ti 5 O 18 Single Crystal

Ba 2 Bi 4 Ti 5 O 18 single crystals were grown, and their dielectric permittivity, conductivity, and ferroelectricity were investigated along the a ‐(or b ‐)axis and the c ‐axis separately. The dielectric permittivity at 1 MHz along the a ‐(or b ‐)axis was 2000 at the Curie temperature (360°C); this value was 8 times greater than that along the c ‐axis. The dc conductivity was greater along the a ‐(or b ‐)axis than that along the c ‐axis, by one order of magnitude. In regard to the ferroelectricity, the saturated remanent polarization was 120 mC/m 2 and the saturated coercive field was 3 MV/m along the a ‐(or b ‐)axis; values of 8.5 mC/m 2 and 0.81 MV/m, respectively, were observed along the c ‐axis. The Ba 2 Bi 4 Ti 5 O 18 single crystals had large electrical anisotropies, which were due to the layered structure.