Properties of lanthanum-doped Bi4Ti3O12–SrBi4Ti4O15 intergrowth ferroelectrics

Lanthanum-doped intergrowth ferroelectrics, (Bi,La)4Ti3O12–Sr(Bi,La)4Ti4O15 [BLT–SBLT(x)], have been prepared. It is found that the remnant polarization (2Pr) of Bi4Ti3O12–SrBi4Ti4O15 (BIT–SBTi) is enlarged. The 2Pr of BLT–SBLT(0.50) has a maximum value of 25.6 μC/cm2. Assuming that the Curie temperature of BLT–SBLT(x) is the average value of the two constituents, La content in both BLT and SBLT can be estimated on the basis of the fact that the crystal structure of BLT–SBLT(x) is not affected by doping. The result shows that when x is not larger than 1.25, La content in BIT is higher than that in SBTi, but when x is 1.50, La content in SBTi is higher. It coincides with the variation of d(118) and the relaxation characteristics of BLT–SBLT(1.50).