A-site (MCe) substitution effects on the structures and properties of CaBi4Ti4O15 ceramics

We investigated the effect of A-site compound substitution on the structure s and propel ties of Ca-0.8 (MCe)(0.1)Bi4Ti4O15 (M denotes Li, Na and K) ce ramics. The samples were prepared by the conventional ceramic technique. Si ntering characteristics of Ca-0.8(MCe)(0.1)Bi4Ti4O15 and CaBi4Ti4O15 cerami cs were discussed. X-ray powder diffraction patterns of the three modified CBT-based compounds show a single phase of bismuth oxide layer type structu re with nz = 4. The hysteresis loops of polarization versus electric field of the four compounds were also measured. A-site compound substitution impr oves the piezoelectric properties and the high-temperature resistivity of t hese materials. A-site (LiCe) and (KCe) substitution not only improves the Curie temperature but also decreases the temperature coefficient of dielect ric constant (T K epsilon). Among the three modified ceramics, only the Cur ie temperature of Ca-0.8(NaCe)(0.1)Bi4Ti4O15 is lower than that of CaBi4Ti4 O15; however, its T K epsilon is the lowest. As a result, all the three mod ified CBT-based ceramics were found to be excellent high-temperature piezoe lectric materials.