A-Site (MCe) Substitution Effects on the Structures and Properties of CaBi₄Ti₄O₁₅ Ceramics

Abstract

We investigated the effect of A-site compound substitution on the structures and properties of Ca 0.8 (MCe) 0.1 Bi 4 Ti 4 O 15 (M denotes Li, Na and K) ceramics. The samples were prepared by the conventional ceramic technique. Sintering characteristics of Ca 0.8 (MCe) 0.1 Bi 4 Ti 4 O 15 and CaBi 4 Ti 4 O 15 ceramics were discussed. X-ray powder diffraction patterns of the three modified CBT-based compounds show a single phase of bismuth oxide layer type structure with m =4. The hysteresis loops of polarization versus electric field of the four compounds were also measured. A-site compound substitution improves the piezoelectric properties and the high-temperature resistivity of these materials. A-site (LiCe) and (KCe) substitution not only improves the Curie temperature but also decreases the temperature coefficient of dielectric constant ( T K ε ). Among the three modified ceramics, only the Curie temperature of Ca 0.8 (NaCe) 0.1 Bi 4 Ti 4 O 15 is lower than that of CaBi 4 Ti 4 O 15 ; however, its T K ε is the lowest. As a result, all the three modified CBT-based ceramics were found to be excellent high-temperature piezoelectric materials.