Polarization Properties of Superlattice-Structured Bi₄Ti₃O₁₂-BaBi₄Ti₄O₁₅ Single Crystals and Ceramics: Comparison with Bi₄Ti₃O₁₂ and BaBi₄Ti₄O₁₅

Abstract

Superlattice-structured Bi 4 Ti 3 O 12 -BaBi 4 Ti 4 O 15 (BiT-BBTi) ceramics and single crystals were prepared, and their crystal structure and polarization properties were compared with those of constituent BiT and BBTi. The Curie temperature ( T C ) of the BiT-BBTi crystals was 540°C, which was 40°C higher than that of the BiT-BBTi ceramics with the stoichiometric composition. The BiT-BBTi ceramics had a remanent polarization ( P r ) of 12 µC/cm 2 , while the spontaneous polarization ( P s ) along the a axis of the BiT-BBTi crystals was 52 µC/cm 2 , which was larger than those of BiT and BBTi crystals. The large P s observed for the BiT-BBTi crystals is suggested to originate from the ferroelectric displacements of the Bi of Bi 2 O 2 layers as well as from the Bi substitution for Ba induced by compositional deviation.