SUBSTITUTION SITE OF LANTHANUM IONS IN LA-DOPED SrBi4Ti4O15 and Bi4Ti3O12-SrBi4Ti4O15

ABSTRACT Ferroelectric ceramics of lanthanum-modified SrBi4Ti4O15 and Bi4Ti3O12-SrBi4Ti4O15 have been synthesized, and Raman spectrum measurements have been carried out at room temperature. The investigation on the Raman spectra suggest that La3+ ions prefer to occupy the A site in the case of x ≤ 0.10, and at higher content they tend to be incorporated into Bi2O2 layers in the La-doped SrBi4Ti4O15. As for La-doped Bi4Ti3O12-SrBi4Ti4O15, the critical content of the doping ions is 0.50. An interesting phenomenon has been noticed that the remnant polarization maximized at about the critical doping content. Thus, it can be concluded that the Bi2O2 layers have a very important effect on the properties in the bismuth layer-structured ferroelectric materials.