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

La/Mn co-doped Bi₄Ti₃O₁₂ ceramics, Bi_3.25La_0.75Ti_3-xMn_xO₁₂ (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 Bi_3.25La_0.75Ti₃O₁₂ 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~°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 Bi_3.25La_0.75Ti_3-xMn_xO₁₂ ceramics is steadily shifted to lower temperature with increasing Mn-doping content. Moreover, the remnant polarisation (P_r) of Bi_3.25La_0.75Ti_3-xMn_xO₁₂ samples increases with Mn-doping content, and the Bi_3.25La_0.75Ti_2.92Mn_0.08O₁₂ sample exhibits the largest P_r of 16.6~μ C/cm².