Ferroelectric and dielectric properties of La/Mn co-doped Bi4Ti3O12 ceramics

La/Mn co-doped Bi4Ti3O12 ceramics, Bi3.25La0.75Ti3-xMnxO12 (x = 0.02, 0.04, 0.06, 0.08), were prepared by the solid-state reaction method. The influence of manganese substitution for the titanium part in Bi3.25La0.75Ti3O12 on the sintering behaviour, microstructure, Raman spectra and electrical properties was investigated. The experimental results show that the phase composition of all samples with and without manganese doping, sintered at 1000 degrees C, consists of a single phase with a bismuth-layered structure belonging to the crystalline phase Bi4Ti3O12. There is no evidence of any impurity phase, but a small change in crystallographic orientation is observed. The Curie temperature of Bi3.25La0.75Ti3-xMnxO12 ceramics is steadily shifted to lower temperature with increasing Mn-doping content. Moreover, the remnant polarisation (P-r) of Bi3.25La0.75Ti3-xMnxO12 samples increases with Mn-doping content, and the Bi3.25La0.75Ti2.92Mn0.08O12 sample exhibits the largest P-r of 16.6 mu C/cm(2).